1.\" $MirOS: src/bin/mksh/mksh.1,v 1.341 2014/09/12 20:23:33 tg Exp $ 2.\" $OpenBSD: ksh.1,v 1.153 2014/08/17 07:15:41 jmc Exp $ 3.\"- 4.\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 5.\" 2010, 2011, 2012, 2013, 2014 6.\" Thorsten Glaser <tg@mirbsd.org> 7.\" 8.\" Provided that these terms and disclaimer and all copyright notices 9.\" are retained or reproduced in an accompanying document, permission 10.\" is granted to deal in this work without restriction, including un‐ 11.\" limited rights to use, publicly perform, distribute, sell, modify, 12.\" merge, give away, or sublicence. 13.\" 14.\" This work is provided “AS IS” and WITHOUT WARRANTY of any kind, to 15.\" the utmost extent permitted by applicable law, neither express nor 16.\" implied; without malicious intent or gross negligence. In no event 17.\" may a licensor, author or contributor be held liable for indirect, 18.\" direct, other damage, loss, or other issues arising in any way out 19.\" of dealing in the work, even if advised of the possibility of such 20.\" damage or existence of a defect, except proven that it results out 21.\" of said person’s immediate fault when using the work as intended. 22.\"- 23.\" Try to make GNU groff and AT&T nroff more compatible 24.\" * ` generates ‘ in gnroff, so use \` 25.\" * ' generates ’ in gnroff, \' generates ´, so use \*(aq 26.\" * - generates ‐ in gnroff, \- generates −, so .tr it to - 27.\" thus use - for hyphens and \- for minus signs and option dashes 28.\" * ~ is size-reduced and placed atop in groff, so use \*(TI 29.\" * ^ is size-reduced and placed atop in groff, so use \*(ha 30.\" * \(en does not work in nroff, so use \*(en 31.\" * <>| are problematic, so redefine and use \*(Lt\*(Gt\*(Ba 32.\" Also make sure to use \& especially with two-letter words. 33.\" The section after the "doc" macropackage has been loaded contains 34.\" additional code to convene between the UCB mdoc macropackage (and 35.\" its variant as BSD mdoc in groff) and the GNU mdoc macropackage. 36.\" 37.ie \n(.g \{\ 38. if \*[.T]ascii .tr \-\N'45' 39. if \*[.T]latin1 .tr \-\N'45' 40. if \*[.T]utf8 .tr \-\N'45' 41. ds <= \[<=] 42. ds >= \[>=] 43. ds Rq \[rq] 44. ds Lq \[lq] 45. ds sL \(aq 46. ds sR \(aq 47. if \*[.T]utf8 .ds sL ` 48. if \*[.T]ps .ds sL ` 49. if \*[.T]utf8 .ds sR ' 50. if \*[.T]ps .ds sR ' 51. ds aq \(aq 52. ds TI \(ti 53. ds ha \(ha 54. ds en \(en 55.\} 56.el \{\ 57. ds aq ' 58. ds TI ~ 59. ds ha ^ 60. ds en \(em 61.\} 62.\" 63.\" Implement .Dd with the Mdocdate RCS keyword 64.\" 65.rn Dd xD 66.de Dd 67.ie \\$1$Mdocdate: \{\ 68. xD \\$2 \\$3, \\$4 69.\} 70.el .xD \\$1 \\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8 71.. 72.\" 73.\" .Dd must come before definition of .Mx, because when called 74.\" with -mandoc, it might implement .Mx itself, but we want to 75.\" use our own definition. And .Dd must come *first*, always. 76.\" 77.Dd $Mdocdate: September 12 2014 $ 78.\" 79.\" Check which macro package we use, and do other -mdoc setup. 80.\" 81.ie \n(.g \{\ 82. if \*[.T]utf8 .tr \[la]\*(Lt 83. if \*[.T]utf8 .tr \[ra]\*(Gt 84. ie d volume-ds-1 .ds tT gnu 85. el .ds tT bsd 86.\} 87.el .ds tT ucb 88.\" 89.\" Implement .Mx (MirBSD) 90.\" 91.ie "\*(tT"gnu" \{\ 92. eo 93. de Mx 94. nr curr-font \n[.f] 95. nr curr-size \n[.ps] 96. ds str-Mx \f[\n[curr-font]]\s[\n[curr-size]u] 97. ds str-Mx1 \*[Tn-font-size]\%MirOS\*[str-Mx] 98. if !\n[arg-limit] \ 99. if \n[.$] \{\ 100. ds macro-name Mx 101. parse-args \$@ 102. \} 103. if (\n[arg-limit] > \n[arg-ptr]) \{\ 104. nr arg-ptr +1 105. ie (\n[type\n[arg-ptr]] == 2) \ 106. as str-Mx1 \~\*[arg\n[arg-ptr]] 107. el \ 108. nr arg-ptr -1 109. \} 110. ds arg\n[arg-ptr] "\*[str-Mx1] 111. nr type\n[arg-ptr] 2 112. ds space\n[arg-ptr] "\*[space] 113. nr num-args (\n[arg-limit] - \n[arg-ptr]) 114. nr arg-limit \n[arg-ptr] 115. if \n[num-args] \ 116. parse-space-vector 117. print-recursive 118.. 119. ec 120. ds sP \s0 121. ds tN \*[Tn-font-size] 122.\} 123.el \{\ 124. de Mx 125. nr cF \\n(.f 126. nr cZ \\n(.s 127. ds aa \&\f\\n(cF\s\\n(cZ 128. if \\n(aC==0 \{\ 129. ie \\n(.$==0 \&MirOS\\*(aa 130. el .aV \\$1 \\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8 \\$9 131. \} 132. if \\n(aC>\\n(aP \{\ 133. nr aP \\n(aP+1 134. ie \\n(C\\n(aP==2 \{\ 135. as b1 \&MirOS\ #\&\\*(A\\n(aP\\*(aa 136. ie \\n(aC>\\n(aP \{\ 137. nr aP \\n(aP+1 138. nR 139. \} 140. el .aZ 141. \} 142. el \{\ 143. as b1 \&MirOS\\*(aa 144. nR 145. \} 146. \} 147.. 148.\} 149.\"- 150.Dt MKSH 1 151.Os MirBSD 152.Sh NAME 153.Nm mksh , 154.Nm sh 155.Nd MirBSD Korn shell 156.Sh SYNOPSIS 157.Nm 158.Bk -words 159.Op Fl +abCefhiklmnprUuvXx 160.Oo 161.Fl T Oo Ar \&! Oc Ns Ar tty 162\*(Ba 163.Ar \&\- 164.Oc 165.Op Fl +o Ar option 166.Oo 167.Fl c Ar string \*(Ba 168.Fl s \*(Ba 169.Ar file 170.Op Ar argument ... 171.Oc 172.Ek 173.Nm builtin-name 174.Op Ar argument ... 175.Sh DESCRIPTION 176.Nm 177is a command interpreter intended for both interactive and shell 178script use. 179Its command language is a superset of the 180.Xr sh C 181shell language and largely compatible to the original Korn shell. 182.Ss I'm an Android user, so what's mksh? 183.Nm mksh 184is a 185.Ux 186shell / command interpreter, similar to 187.Nm COMMAND.COM 188or 189.Nm CMD.EXE , 190which has been included with 191.Tn Android Open Source Project 192for a while now. 193Basically, it's a program that runs in a terminal (console window), 194takes user input and runs commands or scripts, which it can also 195be asked to do by other programs, even in the background. 196Any privilege pop-ups you might be encountering are thus not 197.Nm mksh 198issues but questions by some other program utilising it. 199.Ss Invocation 200Most builtins can be called directly, for example if a link points from its 201name to the shell; not all make sense, have been tested or work at all though. 202.Pp 203The options are as follows: 204.Bl -tag -width XcXstring 205.It Fl c Ar string 206.Nm 207will execute the command(s) contained in 208.Ar string . 209.It Fl i 210Interactive shell. 211A shell that reads commands from standard input is 212.Dq interactive 213if this 214option is used or if both standard input and standard error are attached 215to a 216.Xr tty 4 . 217An interactive shell has job control enabled, ignores the 218.Dv SIGINT , 219.Dv SIGQUIT , 220and 221.Dv SIGTERM 222signals, and prints prompts before reading input (see the 223.Ev PS1 224and 225.Ev PS2 226parameters). 227It also processes the 228.Ev ENV 229parameter or the 230.Pa mkshrc 231file (see below). 232For non-interactive shells, the 233.Ic trackall 234option is on by default (see the 235.Ic set 236command below). 237.It Fl l 238Login shell. 239If the basename the shell is called with (i.e. argv[0]) 240starts with 241.Ql \- 242or if this option is used, 243the shell is assumed to be a login shell; see 244.Sx Startup files 245below. 246.It Fl p 247Privileged shell. 248A shell is 249.Dq privileged 250if the real user ID or group ID does not match the 251effective user ID or group ID (see 252.Xr getuid 2 253and 254.Xr getgid 2 ) . 255Clearing the privileged option causes the shell to set 256its effective user ID (group ID) to its real user ID (group ID). 257For further implications, see 258.Sx Startup files . 259If the shell is privileged and this flag is not explicitly set, the 260.Dq privileged 261option is cleared automatically after processing the startup files. 262.It Fl r 263Restricted shell. 264A shell is 265.Dq restricted 266if this 267option is used. 268The following restrictions come into effect after the shell processes any 269profile and 270.Ev ENV 271files: 272.Pp 273.Bl -bullet -compact 274.It 275The 276.Ic cd 277.Po and Ic chdir Pc 278command is disabled. 279.It 280The 281.Ev SHELL , 282.Ev ENV , 283and 284.Ev PATH 285parameters cannot be changed. 286.It 287Command names can't be specified with absolute or relative paths. 288.It 289The 290.Fl p 291option of the built-in command 292.Ic command 293can't be used. 294.It 295Redirections that create files can't be used (i.e.\& 296.Ql \*(Gt , 297.Ql \*(Gt\*(Ba , 298.Ql \*(Gt\*(Gt , 299.Ql \*(Lt\*(Gt ) . 300.El 301.It Fl s 302The shell reads commands from standard input; all non-option arguments 303are positional parameters. 304.It Fl T Ar name 305Spawn 306.Nm 307on the 308.Xr tty 4 309device given. 310The paths 311.Ar name , 312.Pa /dev/ttyC Ns Ar name 313and 314.Pa /dev/tty Ns Ar name 315are attempted in order. 316Unless 317.Ar name 318begins with an exclamation mark 319.Pq Sq \&! , 320this is done in a subshell and returns immediately. 321If 322.Ar name 323is a dash 324.Pq Sq \&\- , 325detach from controlling terminal (daemonise) instead. 326.El 327.Pp 328In addition to the above, the options described in the 329.Ic set 330built-in command can also be used on the command line: 331both 332.Op Fl +abCefhkmnuvXx 333and 334.Op Fl +o Ar option 335can be used for single letter or long options, respectively. 336.Pp 337If neither the 338.Fl c 339nor the 340.Fl s 341option is specified, the first non-option argument specifies the name 342of a file the shell reads commands from. 343If there are no non-option 344arguments, the shell reads commands from the standard input. 345The name of the shell (i.e. the contents of $0) 346is determined as follows: if the 347.Fl c 348option is used and there is a non-option argument, it is used as the name; 349if commands are being read from a file, the file is used as the name; 350otherwise, the basename the shell was called with (i.e. argv[0]) is used. 351.Pp 352The exit status of the shell is 127 if the command file specified on the 353command line could not be opened, or non-zero if a fatal syntax error 354occurred during the execution of a script. 355In the absence of fatal errors, 356the exit status is that of the last command executed, or zero, if no 357command is executed. 358.Ss Startup files 359For the actual location of these files, see 360.Sx FILES . 361A login shell processes the system profile first. 362A privileged shell then processes the suid profile. 363A non-privileged login shell processes the user profile next. 364A non-privileged interactive shell checks the value of the 365.Ev ENV 366parameter after subjecting it to parameter, command, arithmetic and tilde 367.Pq Sq \*(TI 368substitution; if unset or empty, the user mkshrc profile is processed; 369otherwise, if a file whose name is the substitution result exists, 370it is processed; non-existence is silently ignored. 371A privileged shell then drops privileges if neither was the 372.Fl p 373option given on the command line nor set during execution of the startup files. 374.Ss Command syntax 375The shell begins parsing its input by removing any backslash-newline 376combinations, then breaking it into 377.Em words . 378Words (which are sequences of characters) are delimited by unquoted whitespace 379characters (space, tab, and newline) or meta-characters 380.Po 381.Ql \*(Lt , 382.Ql \*(Gt , 383.Ql \*(Ba , 384.Ql \&; , 385.Ql \&( , 386.Ql \&) , 387and 388.Ql & 389.Pc . 390Aside from delimiting words, spaces and tabs are ignored, while newlines 391usually delimit commands. 392The meta-characters are used in building the following 393.Em tokens : 394.Ql \*(Lt , 395.Ql \*(Lt& , 396.Ql \*(Lt\*(Lt , 397.Ql \*(Lt\*(Lt\*(Lt , 398.Ql \*(Gt , 399.Ql \*(Gt& , 400.Ql \*(Gt\*(Gt , 401.Ql &\*(Gt , 402etc. are used to specify redirections (see 403.Sx Input/output redirection 404below); 405.Ql \*(Ba 406is used to create pipelines; 407.Ql \*(Ba& 408is used to create co-processes (see 409.Sx Co-processes 410below); 411.Ql \&; 412is used to separate commands; 413.Ql & 414is used to create asynchronous pipelines; 415.Ql && 416and 417.Ql \*(Ba\*(Ba 418are used to specify conditional execution; 419.Ql ;; , 420.Ql ;&\& 421and 422.Ql ;\*(Ba\& 423are used in 424.Ic case 425statements; 426.Ql \&(( .. )) 427is used in arithmetic expressions; 428and lastly, 429.Ql \&( .. )\& 430is used to create subshells. 431.Pp 432Whitespace and meta-characters can be quoted individually using a backslash 433.Pq Sq \e , 434or in groups using double 435.Pq Sq \&" 436or single 437.Pq Sq \*(aq 438quotes. 439Note that the following characters are also treated specially by the 440shell and must be quoted if they are to represent themselves: 441.Ql \e , 442.Ql \&" , 443.Ql \*(aq , 444.Ql # , 445.Ql $ , 446.Ql \` , 447.Ql \*(TI , 448.Ql { , 449.Ql } , 450.Ql * , 451.Ql \&? , 452and 453.Ql \&[ . 454The first three of these are the above mentioned quoting characters (see 455.Sx Quoting 456below); 457.Ql # , 458if used at the beginning of a word, introduces a comment \*(en everything after 459the 460.Ql # 461up to the nearest newline is ignored; 462.Ql $ 463is used to introduce parameter, command, and arithmetic substitutions (see 464.Sx Substitution 465below); 466.Ql \` 467introduces an old-style command substitution (see 468.Sx Substitution 469below); 470.Ql \*(TI 471begins a directory expansion (see 472.Sx Tilde expansion 473below); 474.Ql { 475and 476.Ql } 477delimit 478.Xr csh 1 Ns -style 479alterations (see 480.Sx Brace expansion 481below); 482and finally, 483.Ql * , 484.Ql \&? , 485and 486.Ql \&[ 487are used in file name generation (see 488.Sx File name patterns 489below). 490.Pp 491As words and tokens are parsed, the shell builds commands, of which there 492are two basic types: 493.Em simple-commands , 494typically programmes that are executed, and 495.Em compound-commands , 496such as 497.Ic for 498and 499.Ic if 500statements, grouping constructs, and function definitions. 501.Pp 502A simple-command consists of some combination of parameter assignments 503(see 504.Sx Parameters 505below), 506input/output redirections (see 507.Sx Input/output redirections 508below), 509and command words; the only restriction is that parameter assignments come 510before any command words. 511The command words, if any, define the command 512that is to be executed and its arguments. 513The command may be a shell built-in command, a function, 514or an external command 515(i.e. a separate executable file that is located using the 516.Ev PATH 517parameter; see 518.Sx Command execution 519below). 520Note that all command constructs have an exit status: for external commands, 521this is related to the status returned by 522.Xr wait 2 523(if the command could not be found, the exit status is 127; if it could not 524be executed, the exit status is 126); the exit status of other command 525constructs (built-in commands, functions, compound-commands, pipelines, lists, 526etc.) are all well-defined and are described where the construct is 527described. 528The exit status of a command consisting only of parameter 529assignments is that of the last command substitution performed during the 530parameter assignment or 0 if there were no command substitutions. 531.Pp 532Commands can be chained together using the 533.Ql \*(Ba 534token to form pipelines, in which the standard output of each command but the 535last is piped (see 536.Xr pipe 2 ) 537to the standard input of the following command. 538The exit status of a pipeline is that of its last command, unless the 539.Ic pipefail 540option is set (see there). 541All commands of a pipeline are executed in separate subshells; 542this is allowed by POSIX but differs from both variants of 543.At 544.Nm ksh , 545where all but the last command were executed in subshells; see the 546.Ic read 547builtin's description for implications and workarounds. 548A pipeline may be prefixed by the 549.Ql \&! 550reserved word which causes the exit status of the pipeline to be logically 551complemented: if the original status was 0, the complemented status will be 1; 552if the original status was not 0, the complemented status will be 0. 553.Pp 554.Em Lists 555of commands can be created by separating pipelines by any of the following 556tokens: 557.Ql && , 558.Ql \*(Ba\*(Ba , 559.Ql & , 560.Ql \*(Ba& , 561and 562.Ql \&; . 563The first two are for conditional execution: 564.Dq Ar cmd1 No && Ar cmd2 565executes 566.Ar cmd2 567only if the exit status of 568.Ar cmd1 569is zero; 570.Ql \*(Ba\*(Ba 571is the opposite \*(en 572.Ar cmd2 573is executed only if the exit status of 574.Ar cmd1 575is non-zero. 576.Ql && 577and 578.Ql \*(Ba\*(Ba 579have equal precedence which is higher than that of 580.Ql & , 581.Ql \*(Ba& , 582and 583.Ql \&; , 584which also have equal precedence. 585Note that the 586.Ql && 587and 588.Ql \*(Ba\*(Ba 589operators are 590.Qq left-associative . 591For example, both of these commands will print only 592.Qq bar : 593.Bd -literal -offset indent 594$ false && echo foo \*(Ba\*(Ba echo bar 595$ true \*(Ba\*(Ba echo foo && echo bar 596.Ed 597.Pp 598The 599.Ql & 600token causes the preceding command to be executed asynchronously; that is, 601the shell starts the command but does not wait for it to complete (the shell 602does keep track of the status of asynchronous commands; see 603.Sx Job control 604below). 605When an asynchronous command is started when job control is disabled 606(i.e. in most scripts), the command is started with signals 607.Dv SIGINT 608and 609.Dv SIGQUIT 610ignored and with input redirected from 611.Pa /dev/null 612(however, redirections specified in the asynchronous command have precedence). 613The 614.Ql \*(Ba& 615operator starts a co-process which is a special kind of asynchronous process 616(see 617.Sx Co-processes 618below). 619Note that a command must follow the 620.Ql && 621and 622.Ql \*(Ba\*(Ba 623operators, while it need not follow 624.Ql & , 625.Ql \*(Ba& , 626or 627.Ql \&; . 628The exit status of a list is that of the last command executed, with the 629exception of asynchronous lists, for which the exit status is 0. 630.Pp 631Compound commands are created using the following reserved words. 632These words 633are only recognised if they are unquoted and if they are used as the first 634word of a command (i.e. they can't be preceded by parameter assignments or 635redirections): 636.Bd -literal -offset indent 637case else function then ! ( 638do esac if time [[ (( 639done fi in until { 640elif for select while } 641.Ed 642.Pp 643In the following compound command descriptions, command lists (denoted as 644.Em list ) 645that are followed by reserved words must end with a semicolon, a newline, or 646a (syntactically correct) reserved word. 647For example, the following are all valid: 648.Bd -literal -offset indent 649$ { echo foo; echo bar; } 650$ { echo foo; echo bar\*(Ltnewline\*(Gt} 651$ { { echo foo; echo bar; } } 652.Ed 653.Pp 654This is not valid: 655.Pp 656.Dl $ { echo foo; echo bar } 657.Bl -tag -width 4n 658.It Pq Ar list 659Execute 660.Ar list 661in a subshell. 662There is no implicit way to pass environment changes from a 663subshell back to its parent. 664.It { Ar list ; No } 665Compound construct; 666.Ar list 667is executed, but not in a subshell. 668Note that 669.Ql { 670and 671.Ql } 672are reserved words, not meta-characters. 673.It Xo case Ar word No in 674.Oo Op \&( 675.Ar pattern 676.Op \*(Ba Ar pat 677.No ... Ns ) 678.Ar list 679.Op ;; \*(Ba ;&\& \*(Ba ;\*(Ba\ \& 680.Oc ... esac 681.Xc 682The 683.Ic case 684statement attempts to match 685.Ar word 686against a specified 687.Ar pattern ; 688the 689.Ar list 690associated with the first successfully matched pattern is executed. 691Patterns used in 692.Ic case 693statements are the same as those used for file name patterns except that the 694restrictions regarding 695.Ql \&. 696and 697.Ql / 698are dropped. 699Note that any unquoted space before and after a pattern is 700stripped; any space within a pattern must be quoted. 701Both the word and the 702patterns are subject to parameter, command, and arithmetic substitution, as 703well as tilde substitution. 704.Pp 705For historical reasons, open and close braces may be used instead of 706.Ic in 707and 708.Ic esac 709e.g.\& 710.Ic case $foo { *) echo bar;; } . 711.Pp 712The list terminators are: 713.Bl -tag -width 4n 714.It Ql ;; 715Terminate after the list. 716.It Ql ;&\& 717Fall through into the next list. 718.It Ql ;\*(Ba\& 719Evaluate the remaining pattern-list tuples. 720.El 721.Pp 722The exit status of a 723.Ic case 724statement is that of the executed 725.Ar list ; 726if no 727.Ar list 728is executed, the exit status is zero. 729.It Xo for Ar name 730.Oo in Ar word No ... Oc ; 731.No do Ar list ; No done 732.Xc 733For each 734.Ar word 735in the specified word list, the parameter 736.Ar name 737is set to the word and 738.Ar list 739is executed. 740If 741.Ic in 742is not used to specify a word list, the positional parameters 743($1, $2, etc.)\& 744are used instead. 745For historical reasons, open and close braces may be used instead of 746.Ic do 747and 748.Ic done 749e.g.\& 750.Ic for i; { echo $i; } . 751The exit status of a 752.Ic for 753statement is the last exit status of 754.Ar list ; 755if 756.Ar list 757is never executed, the exit status is zero. 758.It Xo if Ar list ; 759.No then Ar list ; 760.Oo elif Ar list ; 761.No then Ar list ; Oc 762.No ... 763.Oo else Ar list ; Oc 764.No fi 765.Xc 766If the exit status of the first 767.Ar list 768is zero, the second 769.Ar list 770is executed; otherwise, the 771.Ar list 772following the 773.Ic elif , 774if any, is executed with similar consequences. 775If all the lists following the 776.Ic if 777and 778.Ic elif Ns s 779fail (i.e. exit with non-zero status), the 780.Ar list 781following the 782.Ic else 783is executed. 784The exit status of an 785.Ic if 786statement is that of non-conditional 787.Ar list 788that is executed; if no non-conditional 789.Ar list 790is executed, the exit status is zero. 791.It Xo select Ar name 792.Oo in Ar word No ... Oc ; 793.No do Ar list ; No done 794.Xc 795The 796.Ic select 797statement provides an automatic method of presenting the user with a menu and 798selecting from it. 799An enumerated list of the specified 800.Ar word Ns (s) 801is printed on standard error, followed by a prompt 802.Po 803.Ev PS3: normally 804.Sq #?\ \& 805.Pc . 806A number corresponding to one of the enumerated words is then read from 807standard input, 808.Ar name 809is set to the selected word (or unset if the selection is not valid), 810.Ev REPLY 811is set to what was read (leading/trailing space is stripped), and 812.Ar list 813is executed. 814If a blank line (i.e. zero or more 815.Ev IFS 816octets) is entered, the menu is reprinted without executing 817.Ar list . 818.Pp 819When 820.Ar list 821completes, the enumerated list is printed if 822.Ev REPLY 823is 824.Dv NULL , 825the prompt is printed, and so on. 826This process continues until an end-of-file 827is read, an interrupt is received, or a 828.Ic break 829statement is executed inside the loop. 830If 831.Dq in word ... 832is omitted, the positional parameters are used 833(i.e. $1, $2, etc.). 834For historical reasons, open and close braces may be used instead of 835.Ic do 836and 837.Ic done 838e.g.\& 839.Ic select i; { echo $i; } . 840The exit status of a 841.Ic select 842statement is zero if a 843.Ic break 844statement is used to exit the loop, non-zero otherwise. 845.It Xo until Ar list ; 846.No do Ar list ; 847.No done 848.Xc 849This works like 850.Ic while , 851except that the body is executed only while the exit status of the first 852.Ar list 853is non-zero. 854.It Xo while Ar list ; 855.No do Ar list ; 856.No done 857.Xc 858A 859.Ic while 860is a pre-checked loop. 861Its body is executed as often as the exit status of the first 862.Ar list 863is zero. 864The exit status of a 865.Ic while 866statement is the last exit status of the 867.Ar list 868in the body of the loop; if the body is not executed, the exit status is zero. 869.It Xo function Ar name 870.No { Ar list ; No } 871.Xc 872Defines the function 873.Ar name 874(see 875.Sx Functions 876below). 877Note that redirections specified after a function definition are 878performed whenever the function is executed, not when the function definition 879is executed. 880.It Ar name Ns \&() Ar command 881Mostly the same as 882.Ic function 883(see 884.Sx Functions 885below). 886Whitespace (space or tab) after 887.Ar name 888will be ignored most of the time. 889.It Xo function Ar name Ns \&() 890.No { Ar list ; No } 891.Xc 892The same as 893.Ar name Ns \&() 894.Pq Nm bash Ns ism . 895The 896.Ic function 897keyword is ignored. 898.It Xo Ic time Op Fl p 899.Op Ar pipeline 900.Xc 901The 902.Sx Command execution 903section describes the 904.Ic time 905reserved word. 906.It \&(( Ar expression No )) 907The arithmetic expression 908.Ar expression 909is evaluated; equivalent to 910.Dq let expression 911(see 912.Sx Arithmetic expressions 913and the 914.Ic let 915command, below). 916.It Bq Bq Ar \ \&expression\ \& 917Similar to the 918.Ic test 919and 920.Ic \&[ ... \&] 921commands (described later), with the following exceptions: 922.Bl -bullet 923.It 924Field splitting and file name generation are not performed on arguments. 925.It 926The 927.Fl a 928.Pq AND 929and 930.Fl o 931.Pq OR 932operators are replaced with 933.Ql && 934and 935.Ql \*(Ba\*(Ba , 936respectively. 937.It 938Operators (e.g.\& 939.Sq Fl f , 940.Sq = , 941.Sq \&! ) 942must be unquoted. 943.It 944Parameter, command, and arithmetic substitutions are performed as expressions 945are evaluated and lazy expression evaluation is used for the 946.Ql && 947and 948.Ql \*(Ba\*(Ba 949operators. 950This means that in the following statement, 951.Ic $(\*(Ltfoo) 952is evaluated if and only if the file 953.Pa foo 954exists and is readable: 955.Bd -literal -offset indent 956$ [[ \-r foo && $(\*(Ltfoo) = b*r ]] 957.Ed 958.It 959The second operand of the 960.Sq != 961and 962.Sq = 963expressions are a subset of patterns (e.g. the comparison 964.Ic \&[[ foobar = f*r ]] 965succeeds). 966This even works indirectly: 967.Bd -literal -offset indent 968$ bar=foobar; baz=\*(aqf*r\*(aq 969$ [[ $bar = $baz ]]; echo $? 970$ [[ $bar = \&"$baz" ]]; echo $? 971.Ed 972.Pp 973Perhaps surprisingly, the first comparison succeeds, 974whereas the second doesn't. 975This does not apply to all extglob metacharacters, currently. 976.El 977.El 978.Ss Quoting 979Quoting is used to prevent the shell from treating characters or words 980specially. 981There are three methods of quoting. 982First, 983.Ql \e 984quotes the following character, unless it is at the end of a line, in which 985case both the 986.Ql \e 987and the newline are stripped. 988Second, a single quote 989.Pq Sq \*(aq 990quotes everything up to the next single quote (this may span lines). 991Third, a double quote 992.Pq Sq \&" 993quotes all characters, except 994.Ql $ , 995.Ql \` 996and 997.Ql \e , 998up to the next unquoted double quote. 999.Ql $ 1000and 1001.Ql \` 1002inside double quotes have their usual meaning (i.e. parameter, command, or 1003arithmetic substitution) except no field splitting is carried out on the 1004results of double-quoted substitutions. 1005If a 1006.Ql \e 1007inside a double-quoted string is followed by 1008.Ql \e , 1009.Ql $ , 1010.Ql \` , 1011or 1012.Ql \&" , 1013it is replaced by the second character; if it is followed by a newline, both 1014the 1015.Ql \e 1016and the newline are stripped; otherwise, both the 1017.Ql \e 1018and the character following are unchanged. 1019.Pp 1020If a single-quoted string is preceded by an unquoted 1021.Ql $ , 1022C style backslash expansion (see below) is applied (even single quote 1023characters inside can be escaped and do not terminate the string then); 1024the expanded result is treated as any other single-quoted string. 1025If a double-quoted string is preceded by an unquoted 1026.Ql $ , 1027the latter is ignored. 1028.Ss Backslash expansion 1029In places where backslashes are expanded, certain C and 1030.At 1031.Nm ksh 1032or GNU 1033.Nm bash 1034style escapes are translated. 1035These include 1036.Ql \ea , 1037.Ql \eb , 1038.Ql \ef , 1039.Ql \en , 1040.Ql \er , 1041.Ql \et , 1042.Ql \eU######## , 1043.Ql \eu#### , 1044and 1045.Ql \ev . 1046For 1047.Ql \eU######## 1048and 1049.Ql \eu#### , 1050.Dq # 1051means a hexadecimal digit, of thich there may be none up to four or eight; 1052these escapes translate a Unicode codepoint to UTF-8. 1053Furthermore, 1054.Ql \eE 1055and 1056.Ql \ee 1057expand to the escape character. 1058.Pp 1059In the 1060.Ic print 1061builtin mode, 1062.Ql \e" , 1063.Ql \e\*(aq , 1064and 1065.Ql \e? 1066are explicitly excluded; 1067octal sequences must have the none up to three octal digits 1068.Dq # 1069prefixed with the digit zero 1070.Pq Ql \e0### ; 1071hexadecimal sequences 1072.Ql \ex## 1073are limited to none up to two hexadecimal digits 1074.Dq # ; 1075both octal and hexadecimal sequences convert to raw octets; 1076.Ql \e# , 1077where # is none of the above, translates to \e# (backslashes are retained). 1078.Pp 1079Backslash expansion in the C style mode slightly differs: octal sequences 1080.Ql \e### 1081must have no digit zero prefixing the one up to three octal digits 1082.Dq # 1083and yield raw octets; hexadecimal sequences 1084.Ql \ex#* 1085greedily eat up as many hexadecimal digits 1086.Dq # 1087as they can and terminate with the first non-hexadecimal digit; 1088these translate a Unicode codepoint to UTF-8. 1089The sequence 1090.Ql \ec# , 1091where 1092.Dq # 1093is any octet, translates to Ctrl-# (which basically means, 1094.Ql \ec? 1095becomes DEL, everything else is bitwise ANDed with 0x1F). 1096Finally, 1097.Ql \e# , 1098where # is none of the above, translates to # (has the backslash trimmed), 1099even if it is a newline. 1100.Ss Aliases 1101There are two types of aliases: normal command aliases and tracked aliases. 1102Command aliases are normally used as a short hand for a long or often used 1103command. 1104The shell expands command aliases (i.e. substitutes the alias name 1105for its value) when it reads the first word of a command. 1106An expanded alias is re-processed to check for more aliases. 1107If a command alias ends in a 1108space or tab, the following word is also checked for alias expansion. 1109The alias expansion process stops when a word that is not an alias is found, 1110when a quoted word is found, or when an alias word that is currently being 1111expanded is found. 1112Aliases are specifically an interactive feature: while they do happen 1113to work in scripts and on the command line in some cases, aliases are 1114expanded during lexing, so their use must be in a separate command tree 1115from their definition; otherwise, the alias will not be found. 1116Noticeably, command lists (separated by semicolon, in command substitutions 1117also by newline) may be one same parse tree. 1118.Pp 1119The following command aliases are defined automatically by the shell: 1120.Bd -literal -offset indent 1121autoload=\*(aqtypeset \-fu\*(aq 1122functions=\*(aqtypeset \-f\*(aq 1123hash=\*(aqalias \-t\*(aq 1124history=\*(aqfc \-l\*(aq 1125integer=\*(aqtypeset \-i\*(aq 1126local=\*(aqtypeset\*(aq 1127login=\*(aqexec login\*(aq 1128nameref=\*(aqtypeset \-n\*(aq 1129nohup=\*(aqnohup \*(aq 1130r=\*(aqfc \-e \-\*(aq 1131stop=\*(aqkill \-STOP\*(aq 1132type=\*(aqwhence \-v\*(aq 1133.Ed 1134.Pp 1135Tracked aliases allow the shell to remember where it found a particular 1136command. 1137The first time the shell does a path search for a command that is 1138marked as a tracked alias, it saves the full path of the command. 1139The next 1140time the command is executed, the shell checks the saved path to see that it 1141is still valid, and if so, avoids repeating the path search. 1142Tracked aliases can be listed and created using 1143.Ic alias \-t . 1144Note that changing the 1145.Ev PATH 1146parameter clears the saved paths for all tracked aliases. 1147If the 1148.Ic trackall 1149option is set (i.e.\& 1150.Ic set \-o Ic trackall 1151or 1152.Ic set \-h ) , 1153the shell tracks all commands. 1154This option is set automatically for non-interactive shells. 1155For interactive shells, only the following commands are 1156automatically tracked: 1157.Xr cat 1 , 1158.Xr cc 1 , 1159.Xr chmod 1 , 1160.Xr cp 1 , 1161.Xr date 1 , 1162.Xr ed 1 , 1163.Xr emacs 1 , 1164.Xr grep 1 , 1165.Xr ls 1 , 1166.Xr make 1 , 1167.Xr mv 1 , 1168.Xr pr 1 , 1169.Xr rm 1 , 1170.Xr sed 1 , 1171.Xr sh 1 , 1172.Xr vi 1 , 1173and 1174.Xr who 1 . 1175.Ss Substitution 1176The first step the shell takes in executing a simple-command is to perform 1177substitutions on the words of the command. 1178There are three kinds of 1179substitution: parameter, command, and arithmetic. 1180Parameter substitutions, 1181which are described in detail in the next section, take the form 1182.Pf $ Ns Ar name 1183or 1184.Pf ${ Ns Ar ... Ns } ; 1185command substitutions take the form 1186.Pf $( Ns Ar command Ns \&) 1187or (deprecated) 1188.Pf \` Ns Ar command Ns \` 1189or (executed in the current environment) 1190.Pf ${\ \& Ar command Ns \&;} 1191and strip trailing newlines; 1192and arithmetic substitutions take the form 1193.Pf $(( Ns Ar expression Ns )) . 1194Parsing the current-environment command substitution requires a space, 1195tab or newline after the opening brace and that the closing brace be 1196recognised as a keyword (i.e. is preceded by a newline or semicolon). 1197They are also called funsubs (function substitutions) and behave like 1198functions in that 1199.Ic local 1200and 1201.Ic return 1202work, and in that 1203.Ic exit 1204terminates the parent shell. 1205.Pp 1206Another variant of substitution are the valsubs (value substitutions) 1207.Pf ${\*(Ba\& Ns Ar command Ns \&;} 1208which are also executed in the current environment, like funsubs, but 1209share their I/O with the parent; instead, they evaluate to whatever 1210the, initially empty, expression-local variable 1211.Ev REPLY 1212is set to within the 1213.Ar command Ns No s . 1214.Pp 1215If a substitution appears outside of double quotes, the results of the 1216substitution are generally subject to word or field splitting according to 1217the current value of the 1218.Ev IFS 1219parameter. 1220The 1221.Ev IFS 1222parameter specifies a list of octets which are used to break a string up 1223into several words; any octets from the set space, tab, and newline that 1224appear in the 1225.Ev IFS 1226octets are called 1227.Dq IFS whitespace . 1228Sequences of one or more 1229.Ev IFS 1230whitespace octets, in combination with zero or one 1231.Pf non- Ev IFS 1232whitespace octets, delimit a field. 1233As a special case, leading and trailing 1234.Ev IFS 1235whitespace is stripped (i.e. no leading or trailing empty field 1236is created by it); leading or trailing 1237.Pf non- Ev IFS 1238whitespace does create an empty field. 1239.Pp 1240Example: If 1241.Ev IFS 1242is set to 1243.Dq \*(Ltspace\*(Gt: , 1244and VAR is set to 1245.Dq \*(Ltspace\*(GtA\*(Ltspace\*(Gt:\*(Ltspace\*(Gt\*(Ltspace\*(GtB::D , 1246the substitution for $VAR results in four fields: 1247.Sq A , 1248.Sq B , 1249.Sq 1250(an empty field), 1251and 1252.Sq D . 1253Note that if the 1254.Ev IFS 1255parameter is set to the 1256.Dv NULL 1257string, no field splitting is done; if the parameter is unset, the default 1258value of space, tab, and newline is used. 1259.Pp 1260Also, note that the field splitting applies only to the immediate result of 1261the substitution. 1262Using the previous example, the substitution for $VAR:E 1263results in the fields: 1264.Sq A , 1265.Sq B , 1266.Sq , 1267and 1268.Sq D:E , 1269not 1270.Sq A , 1271.Sq B , 1272.Sq , 1273.Sq D , 1274and 1275.Sq E . 1276This behavior is POSIX compliant, but incompatible with some other shell 1277implementations which do field splitting on the word which contained the 1278substitution or use 1279.Dv IFS 1280as a general whitespace delimiter. 1281.Pp 1282The results of substitution are, unless otherwise specified, also subject to 1283brace expansion and file name expansion (see the relevant sections below). 1284.Pp 1285A command substitution is replaced by the output generated by the specified 1286command which is run in a subshell. 1287For 1288.Pf $( Ns Ar command Ns \&) 1289and 1290.Pf ${\ \& Ar command Ns \&;} 1291substitutions, normal quoting rules are used when 1292.Ar command 1293is parsed; however, for the deprecated 1294.Pf \` Ns Ar command Ns \` 1295form, a 1296.Ql \e 1297followed by any of 1298.Ql $ , 1299.Ql \` , 1300or 1301.Ql \e 1302is stripped (a 1303.Ql \e 1304followed by any other character is unchanged). 1305As a special case in command substitutions, a command of the form 1306.Pf \*(Lt Ar file 1307is interpreted to mean substitute the contents of 1308.Ar file . 1309Note that 1310.Ic $(\*(Ltfoo) 1311has the same effect as 1312.Ic $(cat foo) . 1313.Pp 1314Note that some shells do not use a recursive parser for command substitutions, 1315leading to failure for certain constructs; to be portable, use as workaround 1316.Ql x=$(cat) \*(Lt\*(Lt"EOF" 1317(or the newline-keeping 1318.Ql x=\*(Lt\*(Lt"EOF" 1319extension) instead to merely slurp the string. 1320.St -p1003.1 1321recommends to use case statements of the form 1322.Ql "x=$(case $foo in (bar) echo $bar ;; (*) echo $baz ;; esac)" 1323instead, which would work but not serve as example for this portability issue. 1324.Bd -literal -offset indent 1325x=$(case $foo in bar) echo $bar ;; *) echo $baz ;; esac) 1326# above fails to parse on old shells; below is the workaround 1327x=$(eval $(cat)) \*(Lt\*(Lt"EOF" 1328case $foo in bar) echo $bar ;; *) echo $baz ;; esac 1329EOF 1330.Ed 1331.Pp 1332Arithmetic substitutions are replaced by the value of the specified expression. 1333For example, the command 1334.Ic print $((2+3*4)) 1335displays 14. 1336See 1337.Sx Arithmetic expressions 1338for a description of an expression. 1339.Ss Parameters 1340Parameters are shell variables; they can be assigned values and their values 1341can be accessed using a parameter substitution. 1342A parameter name is either one 1343of the special single punctuation or digit character parameters described 1344below, or a letter followed by zero or more letters or digits 1345.Po 1346.Ql _ 1347counts as a letter 1348.Pc . 1349The latter form can be treated as arrays by appending an array index of the 1350form 1351.Op Ar expr 1352where 1353.Ar expr 1354is an arithmetic expression. 1355Array indices in 1356.Nm 1357are limited to the range 0 through 4294967295, inclusive. 1358That is, they are a 32-bit unsigned integer. 1359.Pp 1360Parameter substitutions take the form 1361.Pf $ Ns Ar name , 1362.Pf ${ Ns Ar name Ns } , 1363or 1364.Sm off 1365.Pf ${ Ar name Oo Ar expr Oc } 1366.Sm on 1367where 1368.Ar name 1369is a parameter name. 1370Substitution of all array elements with 1371.Pf ${ Ns Ar name Ns \&[*]} 1372and 1373.Pf ${ Ns Ar name Ns \&[@]} 1374works equivalent to $* and $@ for positional parameters. 1375If substitution is performed on a parameter 1376(or an array parameter element) 1377that is not set, a null string is substituted unless the 1378.Ic nounset 1379option 1380.Po 1381.Ic set Fl o Ic nounset 1382or 1383.Ic set Fl u 1384.Pc 1385is set, in which case an error occurs. 1386.Pp 1387Parameters can be assigned values in a number of ways. 1388First, the shell implicitly sets some parameters like 1389.Ql # , 1390.Ql PWD , 1391and 1392.Ql $ ; 1393this is the only way the special single character parameters are set. 1394Second, parameters are imported from the shell's environment at startup. 1395Third, parameters can be assigned values on the command line: for example, 1396.Ic FOO=bar 1397sets the parameter 1398.Dq FOO 1399to 1400.Dq bar ; 1401multiple parameter assignments can be given on a single command line and they 1402can be followed by a simple-command, in which case the assignments are in 1403effect only for the duration of the command (such assignments are also 1404exported; see below for the implications of this). 1405Note that both the parameter name and the 1406.Ql = 1407must be unquoted for the shell to recognise a parameter assignment. 1408The construct 1409.Ic FOO+=baz 1410is also recognised; the old and new values are immediately concatenated. 1411The fourth way of setting a parameter is with the 1412.Ic export , 1413.Ic global , 1414.Ic readonly , 1415and 1416.Ic typeset 1417commands; see their descriptions in the 1418.Sx Command execution 1419section. 1420Fifth, 1421.Ic for 1422and 1423.Ic select 1424loops set parameters as well as the 1425.Ic getopts , 1426.Ic read , 1427and 1428.Ic set \-A 1429commands. 1430Lastly, parameters can be assigned values using assignment operators 1431inside arithmetic expressions (see 1432.Sx Arithmetic expressions 1433below) or using the 1434.Sm off 1435.Pf ${ Ar name No = Ar value No } 1436.Sm on 1437form of the parameter substitution (see below). 1438.Pp 1439Parameters with the export attribute (set using the 1440.Ic export 1441or 1442.Ic typeset Fl x 1443commands, or by parameter assignments followed by simple commands) are put in 1444the environment (see 1445.Xr environ 7 ) 1446of commands run by the shell as 1447.Ar name Ns = Ns Ar value 1448pairs. 1449The order in which parameters appear in the environment of a command is 1450unspecified. 1451When the shell starts up, it extracts parameters and their values 1452from its environment and automatically sets the export attribute for those 1453parameters. 1454.Pp 1455Modifiers can be applied to the 1456.Pf ${ Ns Ar name Ns } 1457form of parameter substitution: 1458.Bl -tag -width Ds 1459.Sm off 1460.It ${ Ar name No :\- Ar word No } 1461.Sm on 1462If 1463.Ar name 1464is set and not 1465.Dv NULL , 1466it is substituted; otherwise, 1467.Ar word 1468is substituted. 1469.Sm off 1470.It ${ Ar name No :+ Ar word No } 1471.Sm on 1472If 1473.Ar name 1474is set and not 1475.Dv NULL , 1476.Ar word 1477is substituted; otherwise, nothing is substituted. 1478.Sm off 1479.It ${ Ar name No := Ar word No } 1480.Sm on 1481If 1482.Ar name 1483is set and not 1484.Dv NULL , 1485it is substituted; otherwise, it is assigned 1486.Ar word 1487and the resulting value of 1488.Ar name 1489is substituted. 1490.Sm off 1491.It ${ Ar name No :? Ar word No } 1492.Sm on 1493If 1494.Ar name 1495is set and not 1496.Dv NULL , 1497it is substituted; otherwise, 1498.Ar word 1499is printed on standard error (preceded by 1500.Ar name : ) 1501and an error occurs (normally causing termination of a shell script, function, 1502or script sourced using the 1503.Sq \&. 1504built-in). 1505If 1506.Ar word 1507is omitted, the string 1508.Dq parameter null or not set 1509is used instead. 1510Currently a bug, if 1511.Ar word 1512is a variable which expands to the null string, the 1513error message is also printed. 1514.El 1515.Pp 1516Note that, for all of the above, 1517.Ar word 1518is actually considered quoted, and special parsing rules apply. 1519The parsing rules also differ on whether the expression is double-quoted: 1520.Ar word 1521then uses double-quoting rules, except for the double quote itself 1522.Pq Sq \&" 1523and the closing brace, which, if backslash escaped, gets quote removal applied. 1524.Pp 1525In the above modifiers, the 1526.Ql \&: 1527can be omitted, in which case the conditions only depend on 1528.Ar name 1529being set (as opposed to set and not 1530.Dv NULL ) . 1531If 1532.Ar word 1533is needed, parameter, command, arithmetic, and tilde substitution are performed 1534on it; if 1535.Ar word 1536is not needed, it is not evaluated. 1537.Pp 1538The following forms of parameter substitution can also be used (if 1539.Ar name 1540is an array, its element #0 will be substituted in a scalar context): 1541.Pp 1542.Bl -tag -width Ds -compact 1543.It Pf ${# Ns Ar name Ns \&} 1544The number of positional parameters if 1545.Ar name 1546is 1547.Ql * , 1548.Ql @ , 1549or not specified; otherwise the length 1550.Pq in characters 1551of the string value of parameter 1552.Ar name . 1553.Pp 1554.It Pf ${# Ns Ar name Ns \&[*]} 1555.It Pf ${# Ns Ar name Ns \&[@]} 1556The number of elements in the array 1557.Ar name . 1558.Pp 1559.It Pf ${% Ns Ar name Ns \&} 1560The width 1561.Pq in screen columns 1562of the string value of parameter 1563.Ar name , 1564or \-1 if 1565.Pf ${ Ns Ar name Ns } 1566contains a control character. 1567.Pp 1568.It Pf ${! Ns Ar name Ns } 1569The name of the variable referred to by 1570.Ar name . 1571This will be 1572.Ar name 1573except when 1574.Ar name 1575is a name reference (bound variable), created by the 1576.Ic nameref 1577command (which is an alias for 1578.Ic typeset Fl n ) . 1579.Pp 1580.It Pf ${! Ns Ar name Ns \&[*]} 1581.It Pf ${! Ns Ar name Ns \&[@]} 1582The names of indices (keys) in the array 1583.Ar name . 1584.Pp 1585.Sm off 1586.It Xo 1587.Pf ${ Ar name 1588.Pf # Ar pattern No } 1589.Xc 1590.It Xo 1591.Pf ${ Ar name 1592.Pf ## Ar pattern No } 1593.Xc 1594.Sm on 1595If 1596.Ar pattern 1597matches the beginning of the value of parameter 1598.Ar name , 1599the matched text is deleted from the result of substitution. 1600A single 1601.Ql # 1602results in the shortest match, and two 1603of them result in the longest match. 1604Cannot be applied to a vector 1605.Pq ${*} or ${@} or ${array[*]} or ${array[@]} . 1606.Pp 1607.Sm off 1608.It Xo 1609.Pf ${ Ar name 1610.Pf % Ar pattern No } 1611.Xc 1612.It Xo 1613.Pf ${ Ar name 1614.Pf %% Ar pattern No } 1615.Xc 1616.Sm on 1617Like ${..#..} substitution, but it deletes from the end of the value. 1618Cannot be applied to a vector. 1619.Pp 1620.Sm off 1621.It Xo 1622.Pf ${ Ar name 1623.Pf / Ar pattern / Ar string No } 1624.Xc 1625.It Xo 1626.Pf ${ Ar name 1627.Pf // Ar pattern / Ar string No } 1628.Xc 1629.Sm on 1630Like ${..#..} substitution, but it replaces the longest match of 1631.Ar pattern , 1632anchored anywhere in the value, with 1633.Ar string . 1634If 1635.Ar pattern 1636begins with 1637.Ql # , 1638it is anchored at the beginning of the value; if it begins with 1639.Ql % , 1640it is anchored at the end. 1641Patterns that are empty or consist only of wildcards are invalid. 1642A single 1643.Ql / 1644replaces the first occurence of the search 1645.Ar pattern , 1646and two of them replace all occurences. 1647If 1648.Pf / Ar string 1649is omitted, the 1650.Ar pattern 1651is replaced by the empty string, i.e. deleted. 1652Cannot be applied to a vector. 1653Inefficiently implemented, may be slow. 1654.Pp 1655.Sm off 1656.It Xo 1657.Pf ${ Ar name : Ns Ar pos 1658.Pf : Ns Ar len Ns } 1659.Xc 1660.Sm on 1661The first 1662.Ar len 1663characters of 1664.Ar name , 1665starting at position 1666.Ar pos , 1667are substituted. 1668Both 1669.Ar pos 1670and 1671.Pf : Ns Ar len 1672are optional. 1673If 1674.Ar pos 1675is negative, counting starts at the end of the string; if it 1676is omitted, it defaults to 0. 1677If 1678.Ar len 1679is omitted or greater than the length of the remaining string, 1680all of it is substituted. 1681Both 1682.Ar pos 1683and 1684.Ar len 1685are evaluated as arithmetic expressions. 1686Currently, 1687.Ar pos 1688must start with a space, opening parenthesis or digit to be recognised. 1689Cannot be applied to a vector. 1690.Pp 1691.It Pf ${ Ns Ar name Ns @#} 1692The hash (using the BAFH algorithm) of the expansion of 1693.Ar name . 1694This is also used internally for the shell's hashtables. 1695.Pp 1696.It Pf ${ Ns Ar name Ns @Q} 1697A quoted expression safe for re-entry, whose value is the value of the 1698.Ar name 1699parameter, is substituted. 1700.El 1701.Pp 1702Note that 1703.Ar pattern 1704may need extended globbing pattern 1705.Pq @(...) , 1706single 1707.Pq \&\*(aq...\&\*(aq 1708or double 1709.Pq \&"...\&" 1710quote escaping unless 1711.Fl o Ic sh 1712is set. 1713.Pp 1714The following special parameters are implicitly set by the shell and cannot be 1715set directly using assignments: 1716.Bl -tag -width "1 .. 9" 1717.It Ev \&! 1718Process ID of the last background process started. 1719If no background processes have been started, the parameter is not set. 1720.It Ev \&# 1721The number of positional parameters ($1, $2, etc.). 1722.It Ev \&$ 1723The PID of the shell, or the PID of the original shell if it is a subshell. 1724Do 1725.Em NOT 1726use this mechanism for generating temporary file names; see 1727.Xr mktemp 1 1728instead. 1729.It Ev \- 1730The concatenation of the current single letter options (see the 1731.Ic set 1732command below for a list of options). 1733.It Ev \&? 1734The exit status of the last non-asynchronous command executed. 1735If the last command was killed by a signal, 1736.Ic $?\& 1737is set to 128 plus the signal number. 1738.It Ev 0 1739The name of the shell, determined as follows: 1740the first argument to 1741.Nm 1742if it was invoked with the 1743.Fl c 1744option and arguments were given; otherwise the 1745.Ar file 1746argument, if it was supplied; 1747or else the basename the shell was invoked with (i.e.\& 1748.Li argv[0] ) . 1749.Ev $0 1750is also set to the name of the current script or 1751the name of the current function, if it was defined with the 1752.Ic function 1753keyword (i.e. a Korn shell style function). 1754.It Ev 1 No .. Ev 9 1755The first nine positional parameters that were supplied to the shell, function, 1756or script sourced using the 1757.Sq \&. 1758built-in. 1759Further positional parameters may be accessed using 1760.Pf ${ Ar number Ns } . 1761.It Ev * 1762All positional parameters (except 0), i.e. $1, $2, $3, ... 1763.br 1764If used 1765outside of double quotes, parameters are separate words (which are subjected 1766to word splitting); if used within double quotes, parameters are separated 1767by the first character of the 1768.Ev IFS 1769parameter (or the empty string if 1770.Ev IFS 1771is 1772.Dv NULL ) . 1773.It Ev @ 1774Same as 1775.Ic $* , 1776unless it is used inside double quotes, in which case a separate word is 1777generated for each positional parameter. 1778If there are no positional parameters, no word is generated. 1779.Ic $@ 1780can be used to access arguments, verbatim, without losing 1781.Dv NULL 1782arguments or splitting arguments with spaces. 1783.El 1784.Pp 1785The following parameters are set and/or used by the shell: 1786.Bl -tag -width "KSH_VERSION" 1787.It Ev _ 1788.Pq underscore 1789When an external command is executed by the shell, this parameter is set in the 1790environment of the new process to the path of the executed command. 1791In interactive use, this parameter is also set in the parent shell to the last 1792word of the previous command. 1793.It Ev BASHPID 1794The PID of the shell or subshell. 1795.It Ev CDPATH 1796Search path for the 1797.Ic cd 1798built-in command. 1799It works the same way as 1800.Ev PATH 1801for those directories not beginning with 1802.Ql / 1803in 1804.Ic cd 1805commands. 1806Note that if 1807.Ev CDPATH 1808is set and does not contain 1809.Sq \&. 1810or contains an empty path, the current directory is not searched. 1811Also, the 1812.Ic cd 1813built-in command will display the resulting directory when a match is found 1814in any search path other than the empty path. 1815.It Ev COLUMNS 1816Set to the number of columns on the terminal or window. 1817Always set, defaults to 80, unless the 1818value as reported by 1819.Xr stty 1 1820is non-zero and sane enough (minimum is 12x3); similar for 1821.Ev LINES . 1822This parameter is used by the interactive line editing modes, and by the 1823.Ic select , 1824.Ic set \-o , 1825and 1826.Ic kill \-l 1827commands to format information columns. 1828Importing from the environment or unsetting this parameter removes the 1829binding to the actual terminal size in favour of the provided value. 1830.It Ev ENV 1831If this parameter is found to be set after any profile files are executed, the 1832expanded value is used as a shell startup file. 1833It typically contains function and alias definitions. 1834.It Ev ERRNO 1835Integer value of the shell's 1836.Va errno 1837variable. 1838It indicates the reason the last system call failed. 1839Not yet implemented. 1840.It Ev EXECSHELL 1841If set, this parameter is assumed to contain the shell that is to be used to 1842execute commands that 1843.Xr execve 2 1844fails to execute and which do not start with a 1845.Dq #! Ns Ar shell 1846sequence. 1847.It Ev FCEDIT 1848The editor used by the 1849.Ic fc 1850command (see below). 1851.It Ev FPATH 1852Like 1853.Ev PATH , 1854but used when an undefined function is executed to locate the file defining the 1855function. 1856It is also searched when a command can't be found using 1857.Ev PATH . 1858See 1859.Sx Functions 1860below for more information. 1861.It Ev HISTFILE 1862The name of the file used to store command history. 1863When assigned to, history is loaded from the specified file. 1864Also, several invocations of the shell will share history if their 1865.Ev HISTFILE 1866parameters all point to the same file. 1867.Pp 1868.Sy Note : 1869If 1870.Ev HISTFILE 1871isn't set, no history file is used. 1872This is different from 1873.At 1874.Nm ksh . 1875.It Ev HISTSIZE 1876The number of commands normally stored for history. 1877The default is 2047. 1878.It Ev HOME 1879The default directory for the 1880.Ic cd 1881command and the value substituted for an unqualified 1882.Ic \*(TI 1883(see 1884.Sx Tilde expansion 1885below). 1886.It Ev IFS 1887Internal field separator, used during substitution and by the 1888.Ic read 1889command, to split values into distinct arguments; normally set to space, tab, 1890and newline. 1891See 1892.Sx Substitution 1893above for details. 1894.Pp 1895.Sy Note : 1896This parameter is not imported from the environment when the shell is 1897started. 1898.It Ev KSHEGID 1899The effective group id of the shell. 1900.It Ev KSHGID 1901The real group id of the shell. 1902.It Ev KSHUID 1903The real user id of the shell. 1904.It Ev KSH_VERSION 1905The name and version of the shell (read-only). 1906See also the version commands in 1907.Sx Emacs editing mode 1908and 1909.Sx Vi editing mode 1910sections, below. 1911.It Ev LINENO 1912The line number of the function or shell script that is currently being 1913executed. 1914.It Ev LINES 1915Set to the number of lines on the terminal or window. 1916Always set, defaults to 24. 1917See 1918.Ev COLUMNS . 1919.It Ev EPOCHREALTIME 1920Time since the epoch, as returned by 1921.Xr gettimeofday 2 , 1922formatted as decimal 1923.Va tv_sec 1924followed by a dot 1925.Pq Sq .\& 1926and 1927.Va tv_usec 1928padded to exactly six decimal digits. 1929.It Ev OLDPWD 1930The previous working directory. 1931Unset if 1932.Ic cd 1933has not successfully changed directories since the shell started, or if the 1934shell doesn't know where it is. 1935.It Ev OPTARG 1936When using 1937.Ic getopts , 1938it contains the argument for a parsed option, if it requires one. 1939.It Ev OPTIND 1940The index of the next argument to be processed when using 1941.Ic getopts . 1942Assigning 1 to this parameter causes 1943.Ic getopts 1944to process arguments from the beginning the next time it is invoked. 1945.It Ev PATH 1946A colon separated list of directories that are searched when looking for 1947commands and files sourced using the 1948.Sq \&. 1949command (see below). 1950An empty string resulting from a leading or trailing 1951colon, or two adjacent colons, is treated as a 1952.Sq \&. 1953(the current directory). 1954.It Ev PGRP 1955The process ID of the shell's process group leader. 1956.It Ev PIPESTATUS 1957An array containing the errorlevel (exit status) codes, 1958one by one, of the last pipeline run in the foreground. 1959.It Ev PPID 1960The process ID of the shell's parent. 1961.It Ev PS1 1962The primary prompt for interactive shells. 1963Parameter, command, and arithmetic 1964substitutions are performed, and 1965.Ql \&! 1966is replaced with the current command number (see the 1967.Ic fc 1968command below). 1969A literal 1970.Ql \&! 1971can be put in the prompt by placing 1972.Ql !! 1973in 1974.Ev PS1 . 1975.Pp 1976The default prompt is 1977.Sq $\ \& 1978for non-root users, 1979.Sq #\ \& 1980for root. 1981If 1982.Nm 1983is invoked by root and 1984.Ev PS1 1985does not contain a 1986.Sq # 1987character, the default value will be used even if 1988.Ev PS1 1989already exists in the environment. 1990.Pp 1991The 1992.Nm 1993distribution comes with a sample 1994.Pa dot.mkshrc 1995containing a sophisticated example, but you might like the following one 1996(note that ${HOSTNAME:=$(hostname)} and the 1997root-vs-user distinguishing clause are (in this example) executed at 1998.Ev PS1 1999assignment time, while the $USER and $PWD are escaped 2000and thus will be evaluated each time a prompt is displayed): 2001.Bd -literal 2002PS1=\*(aq${USER:=$(id \-un)}\*(aq"@${HOSTNAME:=$(hostname)}:\e$PWD $( 2003 if (( USER_ID )); then print \e$; else print \e#; fi) " 2004.Ed 2005.Pp 2006Note that since the command-line editors try to figure out how long the prompt 2007is (so they know how far it is to the edge of the screen), escape codes in 2008the prompt tend to mess things up. 2009You can tell the shell not to count certain 2010sequences (such as escape codes) by prefixing your prompt with a 2011character (such as Ctrl-A) followed by a carriage return and then delimiting 2012the escape codes with this character. 2013Any occurences of that character in the prompt are not printed. 2014By the way, don't blame me for 2015this hack; it's derived from the original 2016.Xr ksh88 1 , 2017which did print the delimiter character so you were out of luck 2018if you did not have any non-printing characters. 2019.Pp 2020Since Backslashes and other special characters may be 2021interpreted by the shell, to set 2022.Ev PS1 2023either escape the backslash itself, 2024or use double quotes. 2025The latter is more practical. 2026This is a more complex example, 2027avoiding to directly enter special characters (for example with 2028.Ic \*(haV 2029in the emacs editing mode), 2030which embeds the current working directory, 2031in reverse video 2032.Pq colour would work, too , 2033in the prompt string: 2034.Bd -literal -offset indent 2035x=$(print \e\e001) 2036PS1="$x$(print \e\er)$x$(tput so)$x\e$PWD$x$(tput se)$x\*(Gt " 2037.Ed 2038.Pp 2039Due to a strong suggestion from David G. Korn, 2040.Nm 2041now also supports the following form: 2042.Bd -literal -offset indent 2043PS1=$'\e1\er\e1\ee[7m\e1$PWD\e1\ee[0m\e1\*(Gt ' 2044.Ed 2045.It Ev PS2 2046Secondary prompt string, by default 2047.Sq \*(Gt\ \& , 2048used when more input is needed to complete a command. 2049.It Ev PS3 2050Prompt used by the 2051.Ic select 2052statement when reading a menu selection. 2053The default is 2054.Sq #?\ \& . 2055.It Ev PS4 2056Used to prefix commands that are printed during execution tracing (see the 2057.Ic set Fl x 2058command below). 2059Parameter, command, and arithmetic substitutions are performed 2060before it is printed. 2061The default is 2062.Sq +\ \& . 2063You may want to set it to 2064.Sq \&[$EPOCHREALTIME]\ \& 2065instead, to include timestamps. 2066.It Ev PWD 2067The current working directory. 2068May be unset or 2069.Dv NULL 2070if the shell doesn't know where it is. 2071.It Ev RANDOM 2072Each time 2073.Ev RANDOM 2074is referenced, it is assigned a number between 0 and 32767 from 2075a Linear Congruential PRNG first. 2076.It Ev REPLY 2077Default parameter for the 2078.Ic read 2079command if no names are given. 2080Also used in 2081.Ic select 2082loops to store the value that is read from standard input. 2083.It Ev SECONDS 2084The number of seconds since the shell started or, if the parameter has been 2085assigned an integer value, the number of seconds since the assignment plus the 2086value that was assigned. 2087.It Ev TMOUT 2088If set to a positive integer in an interactive shell, it specifies the maximum 2089number of seconds the shell will wait for input after printing the primary 2090prompt 2091.Pq Ev PS1 . 2092If the time is exceeded, the shell exits. 2093.It Ev TMPDIR 2094The directory temporary shell files are created in. 2095If this parameter is not 2096set, or does not contain the absolute path of a writable directory, temporary 2097files are created in 2098.Pa /tmp . 2099.It Ev USER_ID 2100The effective user id of the shell. 2101.El 2102.Ss Tilde expansion 2103Tilde expansion which is done in parallel with parameter substitution, is done 2104on words starting with an unquoted 2105.Ql \*(TI . 2106The characters following the tilde, up to the first 2107.Ql / , 2108if any, are assumed to be a login name. 2109If the login name is empty, 2110.Ql + , 2111or 2112.Ql \- , 2113the value of the 2114.Ev HOME , 2115.Ev PWD , 2116or 2117.Ev OLDPWD 2118parameter is substituted, respectively. 2119Otherwise, the password file is 2120searched for the login name, and the tilde expression is substituted with the 2121user's home directory. 2122If the login name is not found in the password file or 2123if any quoting or parameter substitution occurs in the login name, no 2124substitution is performed. 2125.Pp 2126In parameter assignments 2127(such as those preceding a simple-command or those occurring 2128in the arguments of 2129.Ic alias , 2130.Ic export , 2131.Ic global , 2132.Ic readonly , 2133and 2134.Ic typeset ) , 2135tilde expansion is done after any assignment 2136(i.e. after the equals sign) 2137or after an unquoted colon 2138.Pq Sq \&: ; 2139login names are also delimited by colons. 2140.Pp 2141The home directory of previously expanded login names are cached and re-used. 2142The 2143.Ic alias \-d 2144command may be used to list, change, and add to this cache (e.g.\& 2145.Ic alias \-d fac=/usr/local/facilities; cd \*(TIfac/bin ) . 2146.Ss Brace expansion (alteration) 2147Brace expressions take the following form: 2148.Bd -unfilled -offset indent 2149.Sm off 2150.Xo 2151.Ar prefix No { Ar str1 No ,..., 2152.Ar strN No } Ar suffix 2153.Xc 2154.Sm on 2155.Ed 2156.Pp 2157The expressions are expanded to 2158.Ar N 2159words, each of which is the concatenation of 2160.Ar prefix , 2161.Ar str Ns i , 2162and 2163.Ar suffix 2164(e.g.\& 2165.Dq a{c,b{X,Y},d}e 2166expands to four words: 2167.Dq ace , 2168.Dq abXe , 2169.Dq abYe , 2170and 2171.Dq ade ) . 2172As noted in the example, brace expressions can be nested and the resulting 2173words are not sorted. 2174Brace expressions must contain an unquoted comma 2175.Pq Sq \&, 2176for expansion to occur (e.g.\& 2177.Ic {} 2178and 2179.Ic {foo} 2180are not expanded). 2181Brace expansion is carried out after parameter substitution 2182and before file name generation. 2183.Ss File name patterns 2184A file name pattern is a word containing one or more unquoted 2185.Ql \&? , 2186.Ql * , 2187.Ql + , 2188.Ql @ , 2189or 2190.Ql \&! 2191characters or 2192.Dq \&[..] 2193sequences. 2194Once brace expansion has been performed, the shell replaces file 2195name patterns with the sorted names of all the files that match the pattern 2196(if no files match, the word is left unchanged). 2197The pattern elements have the following meaning: 2198.Bl -tag -width Ds 2199.It \&? 2200Matches any single character. 2201.It \&* 2202Matches any sequence of octets. 2203.It \&[..] 2204Matches any of the octets inside the brackets. 2205Ranges of octets can be specified by separating two octets by a 2206.Ql \- 2207(e.g.\& 2208.Dq \&[a0\-9] 2209matches the letter 2210.Sq a 2211or any digit). 2212In order to represent itself, a 2213.Ql \- 2214must either be quoted or the first or last octet in the octet list. 2215Similarly, a 2216.Ql \&] 2217must be quoted or the first octet in the list if it is to represent itself 2218instead of the end of the list. 2219Also, a 2220.Ql \&! 2221appearing at the start of the list has special meaning (see below), so to 2222represent itself it must be quoted or appear later in the list. 2223.It \&[!..] 2224Like [..], 2225except it matches any octet not inside the brackets. 2226.Sm off 2227.It *( Ar pattern\*(Ba No ...\*(Ba Ar pattern ) 2228.Sm on 2229Matches any string of octets that matches zero or more occurrences of the 2230specified patterns. 2231Example: The pattern 2232.Ic *(foo\*(Babar) 2233matches the strings 2234.Dq , 2235.Dq foo , 2236.Dq bar , 2237.Dq foobarfoo , 2238etc. 2239.Sm off 2240.It +( Ar pattern\*(Ba No ...\*(Ba Ar pattern ) 2241.Sm on 2242Matches any string of octets that matches one or more occurrences of the 2243specified patterns. 2244Example: The pattern 2245.Ic +(foo\*(Babar) 2246matches the strings 2247.Dq foo , 2248.Dq bar , 2249.Dq foobar , 2250etc. 2251.Sm off 2252.It ?( Ar pattern\*(Ba No ...\*(Ba Ar pattern ) 2253.Sm on 2254Matches the empty string or a string that matches one of the specified 2255patterns. 2256Example: The pattern 2257.Ic ?(foo\*(Babar) 2258only matches the strings 2259.Dq , 2260.Dq foo , 2261and 2262.Dq bar . 2263.Sm off 2264.It @( Ar pattern\*(Ba No ...\*(Ba Ar pattern ) 2265.Sm on 2266Matches a string that matches one of the specified patterns. 2267Example: The pattern 2268.Ic @(foo\*(Babar) 2269only matches the strings 2270.Dq foo 2271and 2272.Dq bar . 2273.Sm off 2274.It !( Ar pattern\*(Ba No ...\*(Ba Ar pattern ) 2275.Sm on 2276Matches any string that does not match one of the specified patterns. 2277Examples: The pattern 2278.Ic !(foo\*(Babar) 2279matches all strings except 2280.Dq foo 2281and 2282.Dq bar ; 2283the pattern 2284.Ic !(*) 2285matches no strings; the pattern 2286.Ic !(?)*\& 2287matches all strings (think about it). 2288.El 2289.Pp 2290Note that complicated globbing, especially with alternatives, 2291is slow; using separate comparisons may (or may not) be faster. 2292.Pp 2293Note that 2294.Nm mksh 2295.Po and Nm pdksh Pc 2296never matches 2297.Sq \&. 2298and 2299.Sq .. , 2300but 2301.At 2302.Nm ksh , 2303Bourne 2304.Nm sh , 2305and GNU 2306.Nm bash 2307do. 2308.Pp 2309Note that none of the above pattern elements match either a period 2310.Pq Sq \&. 2311at the start of a file name or a slash 2312.Pq Sq / , 2313even if they are explicitly used in a [..] sequence; also, the names 2314.Sq \&. 2315and 2316.Sq .. 2317are never matched, even by the pattern 2318.Sq .* . 2319.Pp 2320If the 2321.Ic markdirs 2322option is set, any directories that result from file name generation are marked 2323with a trailing 2324.Ql / . 2325.Ss Input/output redirection 2326When a command is executed, its standard input, standard output, and standard 2327error (file descriptors 0, 1, and 2, respectively) are normally inherited from 2328the shell. 2329Three exceptions to this are commands in pipelines, for which 2330standard input and/or standard output are those set up by the pipeline, 2331asynchronous commands created when job control is disabled, for which standard 2332input is initially set to be from 2333.Pa /dev/null , 2334and commands for which any of the following redirections have been specified: 2335.Bl -tag -width XXxxmarker 2336.It \*(Gt Ar file 2337Standard output is redirected to 2338.Ar file . 2339If 2340.Ar file 2341does not exist, it is created; if it does exist, is a regular file, and the 2342.Ic noclobber 2343option is set, an error occurs; otherwise, the file is truncated. 2344Note that this means the command 2345.Ic cmd \*(Ltfoo \*(Gtfoo 2346will open 2347.Ar foo 2348for reading and then truncate it when it opens it for writing, before 2349.Ar cmd 2350gets a chance to actually read 2351.Ar foo . 2352.It \*(Gt\*(Ba Ar file 2353Same as 2354.Ic \*(Gt , 2355except the file is truncated, even if the 2356.Ic noclobber 2357option is set. 2358.It \*(Gt\*(Gt Ar file 2359Same as 2360.Ic \*(Gt , 2361except if 2362.Ar file 2363exists it is appended to instead of being truncated. 2364Also, the file is opened 2365in append mode, so writes always go to the end of the file (see 2366.Xr open 2 ) . 2367.It \*(Lt Ar file 2368Standard input is redirected from 2369.Ar file , 2370which is opened for reading. 2371.It \*(Lt\*(Gt Ar file 2372Same as 2373.Ic \*(Lt , 2374except the file is opened for reading and writing. 2375.It \*(Lt\*(Lt Ar marker 2376After reading the command line containing this kind of redirection (called a 2377.Dq here document ) , 2378the shell copies lines from the command source into a temporary file until a 2379line matching 2380.Ar marker 2381is read. 2382When the command is executed, standard input is redirected from the 2383temporary file. 2384If 2385.Ar marker 2386contains no quoted characters, the contents of the temporary file are processed 2387as if enclosed in double quotes each time the command is executed, so 2388parameter, command, and arithmetic substitutions are performed, along with 2389backslash 2390.Pq Sq \e 2391escapes for 2392.Ql $ , 2393.Ql \` , 2394.Ql \e , 2395and 2396.Ql \enewline , 2397but not for 2398.Ql \&" . 2399If multiple here documents are used on the same command line, they are saved in 2400order. 2401.Pp 2402If no 2403.Ar marker 2404is given, the here document ends at the next 2405.Ic \*(Lt\*(Lt 2406and substitution will be performed. 2407If 2408.Ar marker 2409is only a set of either single 2410.Dq \*(aq\*(aq 2411or double 2412.Sq \&"" 2413quotes with nothing in between, the here document ends at the next empty line 2414and substitution will not be performed. 2415.It \*(Lt\*(Lt\- Ar marker 2416Same as 2417.Ic \*(Lt\*(Lt , 2418except leading tabs are stripped from lines in the here document. 2419.It \*(Lt\*(Lt\*(Lt Ar word 2420Same as 2421.Ic \*(Lt\*(Lt , 2422except that 2423.Ar word 2424.Em is 2425the here document. 2426This is called a here string. 2427.It \*(Lt& Ar fd 2428Standard input is duplicated from file descriptor 2429.Ar fd . 2430.Ar fd 2431can be a number, indicating the number of an existing file descriptor; 2432the letter 2433.Ql p , 2434indicating the file descriptor associated with the output of the current 2435co-process; or the character 2436.Ql \- , 2437indicating standard input is to be closed. 2438Note that 2439.Ar fd 2440is limited to a single digit in most shell implementations. 2441.It \*(Gt& Ar fd 2442Same as 2443.Ic \*(Lt& , 2444except the operation is done on standard output. 2445.It &\*(Gt Ar file 2446Same as 2447.Ic \*(Gt Ar file 2\*(Gt&1 . 2448This is a GNU 2449.Nm bash 2450extension supported by 2451.Nm 2452which also supports the preceding explicit fd number, for example, 2453.Ic 3&\*(Gt Ar file 2454is the same as 2455.Ic 3\*(Gt Ar file 2\*(Gt&3 2456in 2457.Nm 2458but a syntax error in GNU 2459.Nm bash . 2460Setting the 2461.Fl o Ar posix 2462or 2463.Fl o Ar sh 2464shell options disable parsing of this redirection; 2465it's a compatibility feature to legacy scripts, to 2466not be used when writing new shell code. 2467.It Xo 2468.No &\*(Gt\*(Ba Ar file , 2469.No &\*(Gt\*(Gt Ar file , 2470.No &\*(Gt& Ar fd 2471.Xc 2472Same as 2473.Ic \*(Gt\*(Ba Ar file , 2474.Ic \*(Gt\*(Gt Ar file , 2475or 2476.Ic \*(Gt& Ar fd , 2477followed by 2478.Ic 2\*(Gt&1 , 2479as above. 2480These are 2481.Nm 2482extensions. 2483.El 2484.Pp 2485In any of the above redirections, the file descriptor that is redirected 2486(i.e. standard input or standard output) 2487can be explicitly given by preceding the 2488redirection with a number (portably, only a single digit). 2489Parameter, command, and arithmetic 2490substitutions, tilde substitutions, and (if the shell is interactive) 2491file name generation are all performed on the 2492.Ar file , 2493.Ar marker , 2494and 2495.Ar fd 2496arguments of redirections. 2497Note, however, that the results of any file name 2498generation are only used if a single file is matched; if multiple files match, 2499the word with the expanded file name generation characters is used. 2500Note 2501that in restricted shells, redirections which can create files cannot be used. 2502.Pp 2503For simple-commands, redirections may appear anywhere in the command; for 2504compound-commands 2505.Po 2506.Ic if 2507statements, etc. 2508.Pc , 2509any redirections must appear at the end. 2510Redirections are processed after 2511pipelines are created and in the order they are given, so the following 2512will print an error with a line number prepended to it: 2513.Pp 2514.D1 $ cat /foo/bar 2\*(Gt&1 \*(Gt/dev/null \*(Ba pr \-n \-t 2515.Pp 2516File descriptors created by input/output redirections are private to the 2517Korn shell, but passed to sub-processes if 2518.Fl o Ic posix 2519or 2520.Fl o Ic sh 2521is set. 2522.Ss Arithmetic expressions 2523Integer arithmetic expressions can be used with the 2524.Ic let 2525command, inside $((..)) expressions, inside array references (e.g.\& 2526.Ar name Ns Bq Ar expr ) , 2527as numeric arguments to the 2528.Ic test 2529command, and as the value of an assignment to an integer parameter. 2530.Pp 2531Expressions are calculated using signed arithmetic and the 2532.Vt mksh_ari_t 2533type (a 32-bit signed integer), unless they begin with a sole 2534.Sq # 2535character, in which case they use 2536.Vt mksh_uari_t 2537.Po a 32-bit unsigned integer Pc . 2538.Pp 2539Expressions may contain alpha-numeric parameter identifiers, array references, 2540and integer constants and may be combined with the following C operators 2541(listed and grouped in increasing order of precedence): 2542.Pp 2543Unary operators: 2544.Bd -literal -offset indent 2545+ \- ! \*(TI ++ \-\- 2546.Ed 2547.Pp 2548Binary operators: 2549.Bd -literal -offset indent 2550, 2551= += \-= *= /= %= \*(Lt\*(Lt\*(Lt= \*(Gt\*(Gt\*(Gt= \*(Lt\*(Lt= \*(Gt\*(Gt= &= \*(ha= \*(Ba= 2552\*(Ba\*(Ba 2553&& 2554\*(Ba 2555\*(ha 2556& 2557== != 2558\*(Lt \*(Lt= \*(Gt \*(Gt= 2559\*(Lt\*(Lt\*(Lt \*(Gt\*(Gt\*(Gt \*(Lt\*(Lt \*(Gt\*(Gt 2560+ \- 2561* / % 2562.Ed 2563.Pp 2564Ternary operators: 2565.Bd -literal -offset indent 2566?: (precedence is immediately higher than assignment) 2567.Ed 2568.Pp 2569Grouping operators: 2570.Bd -literal -offset indent 2571( ) 2572.Ed 2573.Pp 2574Integer constants and expressions are calculated using an exactly 32-bit 2575wide, signed or unsigned, type with silent wraparound on integer overflow. 2576Integer constants may be specified with arbitrary bases using the notation 2577.Ar base Ns # Ns Ar number , 2578where 2579.Ar base 2580is a decimal integer specifying the base, and 2581.Ar number 2582is a number in the specified base. 2583Additionally, base-16 integers may be specified by prefixing them with 2584.Sq 0x 2585.Pq case-insensitive 2586in all forms of arithmetic expressions, except as numeric arguments to the 2587.Ic test 2588built-in command. 2589Prefixing numbers with a sole digit zero 2590.Pq Sq 0 2591leads to the shell interpreting it as base-8 (octal) integer in 2592.Ic posix 2593mode 2594.Em only ; 2595historically, (pd)ksh has never done so either anyway, 2596and it's unsafe to do that, but POSIX demands it nowadays. 2597As a special 2598.Nm mksh 2599extension, numbers to the base of one are treated as either (8-bit 2600transparent) ASCII or Unicode codepoints, depending on the shell's 2601.Ic utf8\-mode 2602flag (current setting). 2603The 2604.At 2605.Nm ksh93 2606syntax of 2607.Dq \*(aqx\*(aq 2608instead of 2609.Dq 1#x 2610is also supported. 2611Note that NUL bytes (integral value of zero) cannot be used. 2612An unset or empty parameter evaluates to 0 in integer context. 2613In Unicode mode, raw octets are mapped into the range EF80..EFFF as in 2614OPTU-8, which is in the PUA and has been assigned by CSUR for this use. 2615If more than one octet in ASCII mode, or a sequence of more than one 2616octet not forming a valid and minimal CESU-8 sequence is passed, the 2617behaviour is undefined (usually, the shell aborts with a parse error, 2618but rarely, it succeeds, e.g. on the sequence C2 20). 2619That's why you should always use ASCII mode unless you know that the 2620input is well-formed UTF-8 in the range of 0000..FFFD. 2621.Pp 2622The operators are evaluated as follows: 2623.Bl -tag -width Ds -offset indent 2624.It unary + 2625Result is the argument (included for completeness). 2626.It unary \- 2627Negation. 2628.It \&! 2629Logical NOT; 2630the result is 1 if argument is zero, 0 if not. 2631.It \*(TI 2632Arithmetic (bit-wise) NOT. 2633.It ++ 2634Increment; must be applied to a parameter (not a literal or other expression). 2635The parameter is incremented by 1. 2636When used as a prefix operator, the result 2637is the incremented value of the parameter; when used as a postfix operator, the 2638result is the original value of the parameter. 2639.It \-\- 2640Similar to 2641.Ic ++ , 2642except the parameter is decremented by 1. 2643.It \&, 2644Separates two arithmetic expressions; the left-hand side is evaluated first, 2645then the right. 2646The result is the value of the expression on the right-hand side. 2647.It = 2648Assignment; the variable on the left is set to the value on the right. 2649.It Xo 2650.No += \-= *= /= %= \*(Lt\*(Lt\*(Lt= \*(Gt\*(Gt\*(Gt= 2651.No \*(Lt\*(Lt= \*(Gt\*(Gt= &= \*(ha= \*(Ba= 2652.Xc 2653Assignment operators. 2654.Sm off 2655.Ao Ar var Ac Xo 2656.Aq Ar op 2657.No = Aq Ar expr 2658.Xc 2659.Sm on 2660is the same as 2661.Sm off 2662.Ao Ar var Ac Xo 2663.No = Aq Ar var 2664.Aq Ar op 2665.Aq Ar expr , 2666.Xc 2667.Sm on 2668with any operator precedence in 2669.Aq Ar expr 2670preserved. 2671For example, 2672.Dq var1 *= 5 + 3 2673is the same as specifying 2674.Dq var1 = var1 * (5 + 3) . 2675.It \*(Ba\*(Ba 2676Logical OR; 2677the result is 1 if either argument is non-zero, 0 if not. 2678The right argument is evaluated only if the left argument is zero. 2679.It && 2680Logical AND; 2681the result is 1 if both arguments are non-zero, 0 if not. 2682The right argument is evaluated only if the left argument is non-zero. 2683.It \*(Ba 2684Arithmetic (bit-wise) OR. 2685.It \*(ha 2686Arithmetic (bit-wise) XOR 2687(exclusive-OR). 2688.It & 2689Arithmetic (bit-wise) AND. 2690.It == 2691Equal; the result is 1 if both arguments are equal, 0 if not. 2692.It != 2693Not equal; the result is 0 if both arguments are equal, 1 if not. 2694.It \*(Lt 2695Less than; the result is 1 if the left argument is less than the right, 0 if 2696not. 2697.It \*(Lt= \*(Gt \*(Gt= 2698Less than or equal, greater than, greater than or equal. 2699See 2700.Ic \*(Lt . 2701.It \*(Lt\*(Lt\*(Lt \*(Gt\*(Gt\*(Gt 2702Rotate left (right); the result is similar to shift (see 2703.Ic \*(Lt\*(Lt ) 2704except that the bits shifted out at one end are shifted in 2705at the other end, instead of zero or sign bits. 2706.It \*(Lt\*(Lt \*(Gt\*(Gt 2707Shift left (right); the result is the left argument with its bits shifted left 2708(right) by the amount given in the right argument. 2709.It + \- * / 2710Addition, subtraction, multiplication, and division. 2711.It % 2712Remainder; the result is the symmetric remainder of the division of the left 2713argument by the right. 2714To get the mathematical modulus of 2715.Dq a Ic mod No b , 2716use the formula 2717.Do 2718.Pq a % b + b 2719.No % b 2720.Dc . 2721.It Xo 2722.Sm off 2723.Aq Ar arg1 ? 2724.Aq Ar arg2 : 2725.Aq Ar arg3 2726.Sm on 2727.Xc 2728If 2729.Aq Ar arg1 2730is non-zero, the result is 2731.Aq Ar arg2 ; 2732otherwise the result is 2733.Aq Ar arg3 . 2734The non-result argument is not evaluated. 2735.El 2736.Ss Co-processes 2737A co-process (which is a pipeline created with the 2738.Sq \*(Ba& 2739operator) is an asynchronous process that the shell can both write to (using 2740.Ic print \-p ) 2741and read from (using 2742.Ic read \-p ) . 2743The input and output of the co-process can also be manipulated using 2744.Ic \*(Gt&p 2745and 2746.Ic \*(Lt&p 2747redirections, respectively. 2748Once a co-process has been started, another can't 2749be started until the co-process exits, or until the co-process's input has been 2750redirected using an 2751.Ic exec Ar n Ns Ic \*(Gt&p 2752redirection. 2753If a co-process's input is redirected in this way, the next 2754co-process to be started will share the output with the first co-process, 2755unless the output of the initial co-process has been redirected using an 2756.Ic exec Ar n Ns Ic \*(Lt&p 2757redirection. 2758.Pp 2759Some notes concerning co-processes: 2760.Bl -bullet 2761.It 2762The only way to close the co-process's input (so the co-process reads an 2763end-of-file) is to redirect the input to a numbered file descriptor and then 2764close that file descriptor: 2765.Ic exec 3\*(Gt&p; exec 3\*(Gt&\- 2766.It 2767In order for co-processes to share a common output, the shell must keep the 2768write portion of the output pipe open. 2769This means that end-of-file will not be 2770detected until all co-processes sharing the co-process's output have exited 2771(when they all exit, the shell closes its copy of the pipe). 2772This can be 2773avoided by redirecting the output to a numbered file descriptor (as this also 2774causes the shell to close its copy). 2775Note that this behaviour is slightly 2776different from the original Korn shell which closes its copy of the write 2777portion of the co-process output when the most recently started co-process 2778(instead of when all sharing co-processes) exits. 2779.It 2780.Ic print \-p 2781will ignore 2782.Dv SIGPIPE 2783signals during writes if the signal is not being trapped or ignored; the same 2784is true if the co-process input has been duplicated to another file descriptor 2785and 2786.Ic print \-u Ns Ar n 2787is used. 2788.El 2789.Ss Functions 2790Functions are defined using either Korn shell 2791.Ic function Ar function-name 2792syntax or the Bourne/POSIX shell 2793.Ar function-name Ns \&() 2794syntax (see below for the difference between the two forms). 2795Functions are like 2796.Li .\(hyscripts 2797(i.e. scripts sourced using the 2798.Sq \&. 2799built-in) 2800in that they are executed in the current environment. 2801However, unlike 2802.Li .\(hyscripts , 2803shell arguments (i.e. positional parameters $1, $2, etc.)\& 2804are never visible inside them. 2805When the shell is determining the location of a command, functions 2806are searched after special built-in commands, before builtins and the 2807.Ev PATH 2808is searched. 2809.Pp 2810An existing function may be deleted using 2811.Ic unset Fl f Ar function-name . 2812A list of functions can be obtained using 2813.Ic typeset +f 2814and the function definitions can be listed using 2815.Ic typeset \-f . 2816The 2817.Ic autoload 2818command (which is an alias for 2819.Ic typeset \-fu ) 2820may be used to create undefined functions: when an undefined function is 2821executed, the shell searches the path specified in the 2822.Ev FPATH 2823parameter for a file with the same name as the function which, if found, is 2824read and executed. 2825If after executing the file the named function is found to 2826be defined, the function is executed; otherwise, the normal command search is 2827continued (i.e. the shell searches the regular built-in command table and 2828.Ev PATH ) . 2829Note that if a command is not found using 2830.Ev PATH , 2831an attempt is made to autoload a function using 2832.Ev FPATH 2833(this is an undocumented feature of the original Korn shell). 2834.Pp 2835Functions can have two attributes, 2836.Dq trace 2837and 2838.Dq export , 2839which can be set with 2840.Ic typeset \-ft 2841and 2842.Ic typeset \-fx , 2843respectively. 2844When a traced function is executed, the shell's 2845.Ic xtrace 2846option is turned on for the function's duration. 2847The 2848.Dq export 2849attribute of functions is currently not used. 2850In the original Korn shell, 2851exported functions are visible to shell scripts that are executed. 2852.Pp 2853Since functions are executed in the current shell environment, parameter 2854assignments made inside functions are visible after the function completes. 2855If this is not the desired effect, the 2856.Ic typeset 2857command can be used inside a function to create a local parameter. 2858Note that 2859.At 2860.Nm ksh93 2861uses static scoping (one global scope, one local scope per function) 2862and allows local variables only on Korn style functions, whereas 2863.Nm mksh 2864uses dynamic scoping (nested scopes of varying locality). 2865Note that special parameters (e.g.\& 2866.Ic \&$$ , $! ) 2867can't be scoped in this way. 2868.Pp 2869The exit status of a function is that of the last command executed in the 2870function. 2871A function can be made to finish immediately using the 2872.Ic return 2873command; this may also be used to explicitly specify the exit status. 2874.Pp 2875Functions defined with the 2876.Ic function 2877reserved word are treated differently in the following ways from functions 2878defined with the 2879.Ic \&() 2880notation: 2881.Bl -bullet 2882.It 2883The $0 parameter is set to the name of the function 2884(Bourne-style functions leave $0 untouched). 2885.It 2886Parameter assignments preceding function calls are not kept in the shell 2887environment (executing Bourne-style functions will keep assignments). 2888.It 2889.Ev OPTIND 2890is saved/reset and restored on entry and exit from the function so 2891.Ic getopts 2892can be used properly both inside and outside the function (Bourne-style 2893functions leave 2894.Ev OPTIND 2895untouched, so using 2896.Ic getopts 2897inside a function interferes with using 2898.Ic getopts 2899outside the function). 2900.It 2901Bourne-style function definitions take precedence over alias dereferences 2902and remove alias definitions upon encounter, while aliases take precedence 2903over Korn-style functions. 2904.El 2905.Pp 2906In the future, the following differences may also be added: 2907.Bl -bullet 2908.It 2909A separate trap/signal environment will be used during the execution of 2910functions. 2911This will mean that traps set inside a function will not affect the 2912shell's traps and signals that are not ignored in the shell (but may be 2913trapped) will have their default effect in a function. 2914.It 2915The EXIT trap, if set in a function, will be executed after the function 2916returns. 2917.El 2918.Ss Command execution 2919After evaluation of command-line arguments, redirections, and parameter 2920assignments, the type of command is determined: a special built-in command, 2921a function, a normal builtin, or the name of a file to execute found using the 2922.Ev PATH 2923parameter. 2924The checks are made in the above order. 2925Special built-in commands differ from other commands in that the 2926.Ev PATH 2927parameter is not used to find them, an error during their execution can 2928cause a non-interactive shell to exit, and parameter assignments that are 2929specified before the command are kept after the command completes. 2930Regular built-in commands are different only in that the 2931.Ev PATH 2932parameter is not used to find them. 2933.Pp 2934The original 2935.Nm ksh 2936and POSIX differ somewhat in which commands are considered 2937special or regular. 2938.Pp 2939POSIX special built-in utilities: 2940.Pp 2941.Ic \&. , \&: , break , continue , 2942.Ic eval , exec , exit , export , 2943.Ic readonly , return , set , shift , 2944.Ic times , trap , unset 2945.Pp 2946Additional 2947.Nm 2948commands keeping assignments: 2949.Pp 2950.Ic builtin , global , typeset , wait 2951.Pp 2952Builtins that are not special: 2953.Pp 2954.Ic [ , alias , bg , bind , 2955.Ic cat , cd , command , echo , 2956.Ic false , fc , fg , getopts , 2957.Ic jobs , kill , let , mknod , 2958.Ic print , pwd , read , realpath , 2959.Ic rename , sleep , suspend , test , 2960.Ic true , ulimit , umask , unalias , 2961.Ic whence 2962.Pp 2963Once the type of command has been determined, any command-line parameter 2964assignments are performed and exported for the duration of the command. 2965.Pp 2966The following describes the special and regular built-in commands: 2967.Pp 2968.Bl -tag -width false -compact 2969.It Ic \&. Ar file Op Ar arg ... 2970This is called the 2971.Dq dot 2972command. 2973Execute the commands in 2974.Ar file 2975in the current environment. 2976The file is searched for in the directories of 2977.Ev PATH . 2978If arguments are given, the positional parameters may be used to access them 2979while 2980.Ar file 2981is being executed. 2982If no arguments are given, the positional parameters are 2983those of the environment the command is used in. 2984.Pp 2985.It Ic \&: Op Ar ... 2986The null command. 2987Exit status is set to zero. 2988.Pp 2989.It Ic \&[ Ar expression Ic \&] 2990See 2991.Ic test . 2992.Pp 2993.It Xo Ic alias 2994.Oo Fl d \*(Ba t Oo Fl r Oc \*(Ba 2995.Cm +\-x Oc 2996.Op Fl p 2997.Op Cm + 2998.Oo Ar name 2999.Op Ns = Ns Ar value 3000.Ar ... Oc 3001.Xc 3002Without arguments, 3003.Ic alias 3004lists all aliases. 3005For any name without a value, the existing alias is listed. 3006Any name with a value defines an alias (see 3007.Sx Aliases 3008above). 3009.Pp 3010When listing aliases, one of two formats is used. 3011Normally, aliases are listed as 3012.Ar name Ns = Ns Ar value , 3013where 3014.Ar value 3015is quoted. 3016If options were preceded with 3017.Ql + , 3018or a lone 3019.Ql + 3020is given on the command line, only 3021.Ar name 3022is printed. 3023.Pp 3024The 3025.Fl d 3026option causes directory aliases which are used in tilde expansion to be 3027listed or set (see 3028.Sx Tilde expansion 3029above). 3030.Pp 3031If the 3032.Fl p 3033option is used, each alias is prefixed with the string 3034.Dq alias\ \& . 3035.Pp 3036The 3037.Fl t 3038option indicates that tracked aliases are to be listed/set (values specified on 3039the command line are ignored for tracked aliases). 3040The 3041.Fl r 3042option indicates that all tracked aliases are to be reset. 3043.Pp 3044The 3045.Fl x 3046option sets 3047.Pq Ic +x No clears 3048the export attribute of an alias, or, if no names are given, lists the aliases 3049with the export attribute (exporting an alias has no effect). 3050.Pp 3051.It Ic bg Op Ar job ... 3052Resume the specified stopped job(s) in the background. 3053If no jobs are specified, 3054.Ic %+ 3055is assumed. 3056See 3057.Sx Job control 3058below for more information. 3059.Pp 3060.It Ic bind Op Fl l 3061The current bindings are listed. 3062If the 3063.Fl l 3064flag is given, 3065.Ic bind 3066instead lists the names of the functions to which keys may be bound. 3067See 3068.Sx Emacs editing mode 3069for more information. 3070.Pp 3071.It Xo Ic bind Op Fl m 3072.Ar string Ns = Ns Op Ar substitute 3073.Ar ... 3074.Xc 3075.It Xo Ic bind 3076.Ar string Ns = Ns Op Ar editing-command 3077.Ar ... 3078.Xc 3079The specified editing command is bound to the given 3080.Ar string , 3081which should consist of a control character 3082optionally preceded by one of the two prefix characters 3083and optionally succeded by a tilde character. 3084Future input of the 3085.Ar string 3086will cause the editing command to be immediately invoked. 3087If the 3088.Fl m 3089flag is given, the specified input 3090.Ar string 3091will afterwards be immediately replaced by the given 3092.Ar substitute 3093string which may contain editing commands but not other macros. 3094If a tilde postfix is given, a tilde trailing the one or 3095two prefices and the control character is ignored, any 3096other trailing character will be processed afterwards. 3097.Pp 3098Control characters may be written using caret notation 3099i.e. \*(haX represents Ctrl-X. 3100Note that although only two prefix characters (usually ESC and \*(haX) 3101are supported, some multi-character sequences can be supported. 3102.Pp 3103The following default bindings show how the arrow keys, the home, end and 3104delete key on a BSD wsvt25, xterm\-xfree86 or GNU screen terminal are bound 3105(of course some escape sequences won't work out quite this nicely): 3106.Bd -literal -offset indent 3107bind \*(aq\*(haX\*(aq=prefix\-2 3108bind \*(aq\*(ha[[\*(aq=prefix\-2 3109bind \*(aq\*(haXA\*(aq=up\-history 3110bind \*(aq\*(haXB\*(aq=down\-history 3111bind \*(aq\*(haXC\*(aq=forward\-char 3112bind \*(aq\*(haXD\*(aq=backward\-char 3113bind \*(aq\*(haX1\*(TI\*(aq=beginning\-of\-line 3114bind \*(aq\*(haX7\*(TI\*(aq=beginning\-of\-line 3115bind \*(aq\*(haXH\*(aq=beginning\-of\-line 3116bind \*(aq\*(haX4\*(TI\*(aq=end\-of\-line 3117bind \*(aq\*(haX8\*(TI\*(aq=end\-of\-line 3118bind \*(aq\*(haXF\*(aq=end\-of\-line 3119bind \*(aq\*(haX3\*(TI\*(aq=delete\-char\-forward 3120.Ed 3121.Pp 3122.It Ic break Op Ar level 3123Exit the 3124.Ar level Ns th 3125inner-most 3126.Ic for , 3127.Ic select , 3128.Ic until , 3129or 3130.Ic while 3131loop. 3132.Ar level 3133defaults to 1. 3134.Pp 3135.It Xo 3136.Ic builtin 3137.Op Fl \- 3138.Ar command Op Ar arg ... 3139.Xc 3140Execute the built-in command 3141.Ar command . 3142.Pp 3143.It Xo 3144.Ic cat 3145.Op Fl u 3146.Op Ar 3147.Xc 3148Read files sequentially, in command line order, and write them to 3149standard output. 3150If a 3151.Ar file 3152is a single dash 3153.Pq Sq - 3154or absent, read from standard input. 3155Unless compiled with 3156.Dv MKSH_NO_EXTERNAL_CAT , 3157if any options are given, an external 3158.Xr cat 1 3159utility is invoked instead if called from the shell. 3160For direct builtin calls, the 3161.Tn POSIX 3162.Fl u 3163option is supported as a no-op. 3164.Pp 3165.It Xo 3166.Ic cd 3167.Op Fl L 3168.Op Ar dir 3169.Xc 3170.It Xo 3171.Ic cd 3172.Fl P Op Fl e 3173.Op Ar dir 3174.Xc 3175.It Xo 3176.Ic chdir 3177.Op Fl eLP 3178.Op Ar dir 3179.Xc 3180Set the working directory to 3181.Ar dir . 3182If the parameter 3183.Ev CDPATH 3184is set, it lists the search path for the directory containing 3185.Ar dir . 3186A 3187.Dv NULL 3188path means the current directory. 3189If 3190.Ar dir 3191is found in any component of the 3192.Ev CDPATH 3193search path other than the 3194.Dv NULL 3195path, the name of the new working directory will be written to standard output. 3196If 3197.Ar dir 3198is missing, the home directory 3199.Ev HOME 3200is used. 3201If 3202.Ar dir 3203is 3204.Ql \- , 3205the previous working directory is used (see the 3206.Ev OLDPWD 3207parameter). 3208.Pp 3209If the 3210.Fl L 3211option (logical path) is used or if the 3212.Ic physical 3213option isn't set (see the 3214.Ic set 3215command below), references to 3216.Sq .. 3217in 3218.Ar dir 3219are relative to the path used to get to the directory. 3220If the 3221.Fl P 3222option (physical path) is used or if the 3223.Ic physical 3224option is set, 3225.Sq .. 3226is relative to the filesystem directory tree. 3227The 3228.Ev PWD 3229and 3230.Ev OLDPWD 3231parameters are updated to reflect the current and old working directory, 3232respectively. 3233If the 3234.Fl e 3235option is set for physical filesystem traversal, and 3236.Ev PWD 3237could not be set, the exit code is 1; greater than 1 if an 3238error occurred, 0 otherwise. 3239.Pp 3240.It Xo 3241.Ic cd 3242.Op Fl eLP 3243.Ar old new 3244.Xc 3245.It Xo 3246.Ic chdir 3247.Op Fl eLP 3248.Ar old new 3249.Xc 3250The string 3251.Ar new 3252is substituted for 3253.Ar old 3254in the current directory, and the shell attempts to change to the new 3255directory. 3256.Pp 3257.It Xo 3258.Ic command 3259.Op Fl pVv 3260.Ar cmd 3261.Op Ar arg ... 3262.Xc 3263If neither the 3264.Fl v 3265nor 3266.Fl V 3267option is given, 3268.Ar cmd 3269is executed exactly as if 3270.Ic command 3271had not been specified, with two exceptions: 3272firstly, 3273.Ar cmd 3274cannot be a shell function; 3275and secondly, special built-in commands lose their specialness 3276(i.e. redirection and utility errors do not cause the shell to 3277exit, and command assignments are not permanent). 3278.Pp 3279If the 3280.Fl p 3281option is given, a default search path is used instead of the current value of 3282.Ev PATH , 3283the actual value of which is system dependent. 3284.Pp 3285If the 3286.Fl v 3287option is given, instead of executing 3288.Ar cmd , 3289information about what would be executed is given (and the same is done for 3290.Ar arg ... ) . 3291For special and regular built-in commands and functions, their names are simply 3292printed; for aliases, a command that defines them is printed; and for commands 3293found by searching the 3294.Ev PATH 3295parameter, the full path of the command is printed. 3296If no command is found 3297(i.e. the path search fails), nothing is printed and 3298.Ic command 3299exits with a non-zero status. 3300The 3301.Fl V 3302option is like the 3303.Fl v 3304option, except it is more verbose. 3305.Pp 3306.It Ic continue Op Ar level 3307Jumps to the beginning of the 3308.Ar level Ns th 3309inner-most 3310.Ic for , 3311.Ic select , 3312.Ic until , 3313or 3314.Ic while 3315loop. 3316.Ar level 3317defaults to 1. 3318.Pp 3319.It Xo 3320.Ic echo 3321.Op Fl Een 3322.Op Ar arg ... 3323.Xc 3324.Em Warning: 3325this utility is not portable; use the Korn shell builtin 3326.Ic print 3327instead. 3328.Pp 3329Prints its arguments (separated by spaces) followed by a newline, to the 3330standard output. 3331The newline is suppressed if any of the arguments contain the 3332backslash sequence 3333.Ql \ec . 3334See the 3335.Ic print 3336command below for a list of other backslash sequences that are recognised. 3337.Pp 3338The options are provided for compatibility with 3339.Bx 3340shell scripts. 3341The 3342.Fl n 3343option suppresses the trailing newline, 3344.Fl e 3345enables backslash interpretation (a no-op, since this is normally done), and 3346.Fl E 3347suppresses backslash interpretation. 3348.Pp 3349If the 3350.Ic posix 3351or 3352.Ic sh 3353option is set or this is a direct builtin call, only the first argument 3354is treated as an option, and only if it is exactly 3355.Dq Fl n . 3356Backslash interpretation is disabled. 3357.Pp 3358.It Ic eval Ar command ... 3359The arguments are concatenated (with spaces between them) to form a single 3360string which the shell then parses and executes in the current environment. 3361.Pp 3362.It Xo 3363.Ic exec 3364.Op Ar command Op Ar arg ... 3365.Xc 3366The command is executed without forking, replacing the shell process. 3367.Pp 3368If no command is given except for I/O redirection, the I/O redirection is 3369permanent and the shell is 3370not replaced. 3371Any file descriptors greater than 2 which are opened or 3372.Xr dup 2 Ns 'd 3373in this way are not made available to other executed commands (i.e. commands 3374that are not built-in to the shell). 3375Note that the Bourne shell differs here; 3376it does pass these file descriptors on. 3377.Pp 3378.It Ic exit Op Ar status 3379The shell exits with the specified exit status. 3380If 3381.Ar status 3382is not specified, the exit status is the current value of the 3383.Ic $?\& 3384parameter. 3385.Pp 3386.It Xo 3387.Ic export 3388.Op Fl p 3389.Op Ar parameter Ns Op = Ns Ar value 3390.Xc 3391Sets the export attribute of the named parameters. 3392Exported parameters are passed in the environment to executed commands. 3393If values are specified, the named parameters are also assigned. 3394.Pp 3395If no parameters are specified, all parameters with the export attribute 3396set are printed one per line; either their names, or, if a 3397.Ql \- 3398with no option letter is specified, name=value pairs, or, with 3399.Fl p , 3400.Ic export 3401commands suitable for re-entry. 3402.Pp 3403.It Ic false 3404A command that exits with a non-zero status. 3405.Pp 3406.It Xo 3407.Ic fc 3408.Oo Fl e Ar editor \*(Ba 3409.Fl l Op Fl n Oc 3410.Op Fl r 3411.Op Ar first Op Ar last 3412.Xc 3413.Ar first 3414and 3415.Ar last 3416select commands from the history. 3417Commands can be selected by history number 3418(negative numbers go backwards from the current, most recent, line) 3419or a string specifying the most recent command starting with that string. 3420The 3421.Fl l 3422option lists the command on standard output, and 3423.Fl n 3424inhibits the default command numbers. 3425The 3426.Fl r 3427option reverses the order of the list. 3428Without 3429.Fl l , 3430the selected commands are edited by the editor specified with the 3431.Fl e 3432option, or if no 3433.Fl e 3434is specified, the editor specified by the 3435.Ev FCEDIT 3436parameter (if this parameter is not set, 3437.Pa /bin/ed 3438is used), and then executed by the shell. 3439.Pp 3440.It Xo 3441.Ic fc 3442.Cm \-e \- \*(Ba Fl s 3443.Op Fl g 3444.Op Ar old Ns = Ns Ar new 3445.Op Ar prefix 3446.Xc 3447Re-execute the selected command (the previous command by default) after 3448performing the optional substitution of 3449.Ar old 3450with 3451.Ar new . 3452If 3453.Fl g 3454is specified, all occurrences of 3455.Ar old 3456are replaced with 3457.Ar new . 3458The meaning of 3459.Cm \-e \- 3460and 3461.Fl s 3462is identical: re-execute the selected command without invoking an editor. 3463This command is usually accessed with the predefined: 3464.Ic alias r=\*(aqfc \-e \-\*(aq 3465.Pp 3466.It Ic fg Op Ar job ... 3467Resume the specified job(s) in the foreground. 3468If no jobs are specified, 3469.Ic %+ 3470is assumed. 3471See 3472.Sx Job control 3473below for more information. 3474.Pp 3475.It Xo 3476.Ic getopts 3477.Ar optstring name 3478.Op Ar arg ... 3479.Xc 3480Used by shell procedures to parse the specified arguments (or positional 3481parameters, if no arguments are given) and to check for legal options. 3482.Ar optstring 3483contains the option letters that 3484.Ic getopts 3485is to recognise. 3486If a letter is followed by a colon, the option is expected to 3487have an argument. 3488Options that do not take arguments may be grouped in a single argument. 3489If an option takes an argument and the option character is not the 3490last character of the argument it is found in, the remainder of the argument is 3491taken to be the option's argument; otherwise, the next argument is the option's 3492argument. 3493.Pp 3494Each time 3495.Ic getopts 3496is invoked, it places the next option in the shell parameter 3497.Ar name 3498and the index of the argument to be processed by the next call to 3499.Ic getopts 3500in the shell parameter 3501.Ev OPTIND . 3502If the option was introduced with a 3503.Ql + , 3504the option placed in 3505.Ar name 3506is prefixed with a 3507.Ql + . 3508When an option requires an argument, 3509.Ic getopts 3510places it in the shell parameter 3511.Ev OPTARG . 3512.Pp 3513When an illegal option or a missing option argument is encountered, a question 3514mark or a colon is placed in 3515.Ar name 3516(indicating an illegal option or missing argument, respectively) and 3517.Ev OPTARG 3518is set to the option character that caused the problem. 3519Furthermore, if 3520.Ar optstring 3521does not begin with a colon, a question mark is placed in 3522.Ar name , 3523.Ev OPTARG 3524is unset, and an error message is printed to standard error. 3525.Pp 3526When the end of the options is encountered, 3527.Ic getopts 3528exits with a non-zero exit status. 3529Options end at the first (non-option 3530argument) argument that does not start with a 3531.Ql \- , 3532or when a 3533.Ql \-\- 3534argument is encountered. 3535.Pp 3536Option parsing can be reset by setting 3537.Ev OPTIND 3538to 1 (this is done automatically whenever the shell or a shell procedure is 3539invoked). 3540.Pp 3541Warning: Changing the value of the shell parameter 3542.Ev OPTIND 3543to a value other than 1, or parsing different sets of arguments without 3544resetting 3545.Ev OPTIND , 3546may lead to unexpected results. 3547.Pp 3548.It global Ar ... 3549See 3550.Ic typeset . 3551.Pp 3552.It Xo 3553.Ic hash 3554.Op Fl r 3555.Op Ar name ... 3556.Xc 3557Without arguments, any hashed executable command pathnames are listed. 3558The 3559.Fl r 3560option causes all hashed commands to be removed from the hash table. 3561Each 3562.Ar name 3563is searched as if it were a command name and added to the hash table if it is 3564an executable command. 3565.Pp 3566.It Xo 3567.Ic jobs 3568.Op Fl lnp 3569.Op Ar job ... 3570.Xc 3571Display information about the specified job(s); if no jobs are specified, all 3572jobs are displayed. 3573The 3574.Fl n 3575option causes information to be displayed only for jobs that have changed 3576state since the last notification. 3577If the 3578.Fl l 3579option is used, the process ID of each process in a job is also listed. 3580The 3581.Fl p 3582option causes only the process group of each job to be printed. 3583See 3584.Sx Job control 3585below for the format of 3586.Ar job 3587and the displayed job. 3588.Pp 3589.It Xo 3590.Ic kill 3591.Oo Fl s Ar signame \*(Ba 3592.No \- Ns Ar signum \*(Ba 3593.No \- Ns Ar signame Oc 3594.No { Ar job \*(Ba pid \*(Ba pgrp No } 3595.Ar ... 3596.Xc 3597Send the specified signal to the specified jobs, process IDs, or process 3598groups. 3599If no signal is specified, the 3600.Dv TERM 3601signal is sent. 3602If a job is specified, the signal is sent to the job's process group. 3603See 3604.Sx Job control 3605below for the format of 3606.Ar job . 3607.Pp 3608.It Xo 3609.Ic kill 3610.Fl l 3611.Op Ar exit-status ... 3612.Xc 3613Print the signal name corresponding to 3614.Ar exit-status . 3615If no arguments are specified, a list of all the signals, their numbers, and 3616a short description of them are printed. 3617.Pp 3618.It Ic let Op Ar expression ... 3619Each expression is evaluated (see 3620.Sx Arithmetic expressions 3621above). 3622If all expressions are successfully evaluated, the exit status is 0 (1) 3623if the last expression evaluated to non-zero (zero). 3624If an error occurs during 3625the parsing or evaluation of an expression, the exit status is greater than 1. 3626Since expressions may need to be quoted, 3627.No \&(( Ar expr No )) 3628is syntactic sugar for 3629.No let \&" Ns Ar expr Ns \&" . 3630.Pp 3631.It Ic let] 3632Internally used alias for 3633.Ic let . 3634.Pp 3635.It Xo 3636.Ic mknod 3637.Op Fl m Ar mode 3638.Ar name 3639.Cm b\*(Bac 3640.Ar major minor 3641.Xc 3642.It Xo 3643.Ic mknod 3644.Op Fl m Ar mode 3645.Ar name 3646.Cm p 3647.Xc 3648Create a device special file. 3649The file type may be 3650.Cm b 3651(block type device), 3652.Cm c 3653(character type device), 3654or 3655.Cm p 3656.Pq named pipe , Tn FIFO . 3657The file created may be modified according to its 3658.Ar mode 3659(via the 3660.Fl m 3661option), 3662.Ar major 3663(major device number), 3664and 3665.Ar minor 3666(minor device number). 3667.Pp 3668See 3669.Xr mknod 8 3670for further information. 3671.Pp 3672.It Xo 3673.Ic print 3674.Oo Fl nprsu Ns Oo Ar n Oc \*(Ba 3675.Fl R Op Fl en Oc 3676.Op Ar argument ... 3677.Xc 3678.Ic print 3679prints its arguments on the standard output, separated by spaces and 3680terminated with a newline. 3681The 3682.Fl n 3683option suppresses the newline. 3684By default, certain C escapes are translated. 3685These include these mentioned in 3686.Sx Backslash expansion 3687above, as well as 3688.Ql \ec , 3689which is equivalent to using the 3690.Fl n 3691option. 3692Backslash expansion may be inhibited with the 3693.Fl r 3694option. 3695The 3696.Fl s 3697option prints to the history file instead of standard output; the 3698.Fl u 3699option prints to file descriptor 3700.Ar n 3701.Po 3702.Ar n 3703defaults to 1 if omitted 3704.Pc ; 3705and the 3706.Fl p 3707option prints to the co-process (see 3708.Sx Co-processes 3709above). 3710.Pp 3711The 3712.Fl R 3713option is used to emulate, to some degree, the 3714.Bx 3715.Xr echo 1 3716command which does not process 3717.Ql \e 3718sequences unless the 3719.Fl e 3720option is given. 3721As above, the 3722.Fl n 3723option suppresses the trailing newline. 3724.Pp 3725.It Ic printf Ar format Op Ar arguments ... 3726Formatted output. 3727Approximately the same as the 3728.Xr printf 1 , 3729utility, except it uses the same 3730.Sx Backslash expansion 3731and I/O code and does hot handle floating point as the rest of 3732.Nm mksh . 3733This is not normally part of 3734.Nm mksh ; 3735however, distributors may have added this as builtin as a speed hack. 3736Do not use in new code. 3737.Pp 3738.It Ic pwd Op Fl LP 3739Print the present working directory. 3740If the 3741.Fl L 3742option is used or if the 3743.Ic physical 3744option isn't set (see the 3745.Ic set 3746command below), the logical path is printed (i.e. the path used to 3747.Ic cd 3748to the current directory). 3749If the 3750.Fl P 3751option (physical path) is used or if the 3752.Ic physical 3753option is set, the path determined from the filesystem (by following 3754.Sq .. 3755directories to the root directory) is printed. 3756.Pp 3757.It Xo 3758.Ic read 3759.Op Fl A \*(Ba Fl a 3760.Op Fl d Ar x 3761.Oo Fl N Ar z \*(Ba 3762.Fl n Ar z Oc 3763.Oo Fl p \*(Ba 3764.Fl u Ns Op Ar n 3765.Oc Op Fl t Ar n 3766.Op Fl rs 3767.Op Ar p ... 3768.Xc 3769Reads a line of input, separates the input into fields using the 3770.Ev IFS 3771parameter (see 3772.Sx Substitution 3773above), and assigns each field to the specified parameters 3774.Ar p . 3775If no parameters are specified, the 3776.Ev REPLY 3777parameter is used to store the result. 3778With the 3779.Fl A 3780and 3781.Fl a 3782options, only no or one parameter is accepted. 3783If there are more parameters than fields, the extra parameters are set to 3784the empty string or 0; if there are more fields than parameters, the last 3785parameter is assigned the remaining fields (including the word separators). 3786.Pp 3787The options are as follows: 3788.Bl -tag -width XuXnX 3789.It Fl A 3790Store the result into the parameter 3791.Ar p 3792(or 3793.Ev REPLY ) 3794as array of words. 3795.It Fl a 3796Store the result without word splitting into the parameter 3797.Ar p 3798(or 3799.Ev REPLY ) 3800as array of characters (wide characters if the 3801.Ic utf8\-mode 3802option is enacted, octets otherwise). 3803.It Fl d Ar x 3804Use the first byte of 3805.Ar x , 3806.Dv NUL 3807if empty, instead of the ASCII newline character as input line delimiter. 3808.It Fl N Ar z 3809Instead of reading till end-of-line, read exactly 3810.Ar z 3811bytes; less if EOF or a timeout occurs. 3812.It Fl n Ar z 3813Instead of reading till end-of-line, read up to 3814.Ar z 3815bytes but return as soon as any bytes are read, e.g.\& from a 3816slow terminal device, or if EOF or a timeout occurs. 3817.It Fl p 3818Read from the currently active co-process, see 3819.Sx Co-processes 3820above for details on this. 3821.It Fl u Ns Op Ar n 3822Read from the file descriptor 3823.Ar n 3824(defaults to 0, i.e.\& standard input). 3825The argument must immediately follow the option character. 3826.It Fl t Ar n 3827Interrupt reading after 3828.Ar n 3829seconds (specified as positive decimal value with an optional fractional part). 3830.It Fl r 3831Normally, the ASCII backslash character escapes the special 3832meaning of the following character and is stripped from the input; 3833.Ic read 3834does not stop when encountering a backslash-newline sequence and 3835does not store that newline in the result. 3836This option enables raw mode, in which backslashes are not processed. 3837.It Fl s 3838The input line is saved to the history. 3839.El 3840.Pp 3841If the input is a terminal, both the 3842.Fl N 3843and 3844.Fl n 3845options set it into raw mode; 3846they read an entire file if \-1 is passed as 3847.Ar z 3848argument. 3849.Pp 3850The first parameter may have a question mark and a string appended to it, in 3851which case the string is used as a prompt (printed to standard error before 3852any input is read) if the input is a 3853.Xr tty 4 3854(e.g.\& 3855.Ic read nfoo?\*(aqnumber of foos: \*(aq ) . 3856.Pp 3857If no input is read or a timeout occurred, 3858.Ic read 3859exits with a non-zero status. 3860.Pp 3861Another handy set of tricks: 3862If 3863.Ic read 3864is run in a loop such as 3865.Ic while read foo; do ...; done 3866then leading whitespace will be removed (IFS) and backslashes processed. 3867You might want to use 3868.Ic while IFS= read \-r foo; do ...; done 3869for pristine I/O. 3870Similarily, when using the 3871.Fl a 3872option, use of the 3873.Fl r 3874option might be prudent; the same applies for: 3875.Bd -literal -offset indent 3876find . \-type f \-print0 \*(Ba \e 3877 while IFS= read \-d \*(aq\*(aq \-r filename; do 3878 print \-r \-\- "found \*(Lt${filename#./}\*(Gt" 3879done 3880.Ed 3881.Pp 3882The inner loop will be executed in a subshell and variable changes 3883cannot be propagated if executed in a pipeline: 3884.Bd -literal -offset indent 3885bar \*(Ba baz \*(Ba while read foo; do ...; done 3886.Ed 3887.Pp 3888Use co-processes instead: 3889.Bd -literal -offset indent 3890bar \*(Ba baz \*(Ba& 3891while read \-p foo; do ...; done 3892exec 3\*(Gt&p; exec 3\*(Gt&\- 3893.Ed 3894.Pp 3895.It Xo 3896.Ic readonly 3897.Op Fl p 3898.Oo Ar parameter 3899.Op Ns = Ns Ar value 3900.Ar ... Oc 3901.Xc 3902Sets the read-only attribute of the named parameters. 3903If values are given, 3904parameters are set to them before setting the attribute. 3905Once a parameter is 3906made read-only, it cannot be unset and its value cannot be changed. 3907.Pp 3908If no parameters are specified, the names of all parameters with the read-only 3909attribute are printed one per line, unless the 3910.Fl p 3911option is used, in which case 3912.Ic readonly 3913commands defining all read-only parameters, including their values, are 3914printed. 3915.Pp 3916.It Xo 3917.Ic realpath 3918.Op Fl \- 3919.Ar name 3920.Xc 3921Prints the resolved absolute pathname corresponding to 3922.Ar name . 3923If 3924.Ar name 3925ends with a slash 3926.Pq Sq / , 3927it's also checked for existence and whether it is a directory; otherwise, 3928.Ic realpath 3929returns 0 if the pathname either exists or can be created immediately, 3930i.e. all but the last component exist and are directories. 3931.Pp 3932.It Xo 3933.Ic rename 3934.Op Fl \- 3935.Ar from to 3936.Xc 3937Renames the file 3938.Ar from 3939to 3940.Ar to . 3941Both must be complete pathnames and on the same device. 3942This builtin is intended for emergency situations where 3943.Pa /bin/mv 3944becomes unusable, and directly calls 3945.Xr rename 2 . 3946.Pp 3947.It Ic return Op Ar status 3948Returns from a function or 3949.Ic .\& 3950script, with exit status 3951.Ar status . 3952If no 3953.Ar status 3954is given, the exit status of the last executed command is used. 3955If used outside of a function or 3956.Ic .\& 3957script, it has the same effect as 3958.Ic exit . 3959Note that 3960.Nm 3961treats both profile and 3962.Ev ENV 3963files as 3964.Ic .\& 3965scripts, while the original Korn shell only treats profiles as 3966.Ic .\& 3967scripts. 3968.Pp 3969.It Xo 3970.Ic set Op Ic +\-abCefhiklmnprsUuvXx 3971.Op Ic +\-o Ar option 3972.Op Ic +\-A Ar name 3973.Op Fl \- 3974.Op Ar arg ... 3975.Xc 3976The 3977.Ic set 3978command can be used to set 3979.Pq Ic \- 3980or clear 3981.Pq Ic + 3982shell options, set the positional parameters, or set an array parameter. 3983Options can be changed using the 3984.Cm +\-o Ar option 3985syntax, where 3986.Ar option 3987is the long name of an option, or using the 3988.Cm +\- Ns Ar letter 3989syntax, where 3990.Ar letter 3991is the option's single letter name (not all options have a single letter name). 3992The following table lists both option letters (if they exist) and long names 3993along with a description of what the option does: 3994.Bl -tag -width 3n 3995.It Fl A Ar name 3996Sets the elements of the array parameter 3997.Ar name 3998to 3999.Ar arg ... 4000If 4001.Fl A 4002is used, the array is reset (i.e. emptied) first; if 4003.Ic +A 4004is used, the first N elements are set (where N is the number of arguments); 4005the rest are left untouched. 4006.Pp 4007An alternative syntax for the command 4008.Ic set \-A foo \-\- a b c 4009which is compatible to 4010.Tn GNU 4011.Nm bash 4012and also supported by 4013.At 4014.Nm ksh93 4015is: 4016.Ic foo=(a b c); foo+=(d e) 4017.Pp 4018Another 4019.At 4020.Nm ksh93 4021and 4022.Tn GNU 4023.Nm bash 4024extension allows specifying the indices used for 4025.Ar arg ... 4026.Pq from the above example, Ic a b c 4027like this: 4028.Ic set \-A foo \-\- [0]=a [1]=b [2]=c 4029or 4030.Ic foo=([0]=a [1]=b [2]=c) 4031which can also be written 4032.Ic foo=([0]=a b c) 4033because indices are incremented automatically. 4034.It Fl a \*(Ba Fl o Ic allexport 4035All new parameters are created with the export attribute. 4036.It Fl b \*(Ba Fl o Ic notify 4037Print job notification messages asynchronously, instead of just before the 4038prompt. 4039Only used if job control is enabled 4040.Pq Fl m . 4041.It Fl C \*(Ba Fl o Ic noclobber 4042Prevent \*(Gt redirection from overwriting existing files. 4043Instead, \*(Gt\*(Ba must be used to force an overwrite. 4044Note that this is not safe to use for creation of temporary files or 4045lockfiles due to a TOCTOU in a check allowing one to redirect output to 4046.Pa /dev/null 4047or other device files even in 4048.Ic noclobber 4049mode. 4050.It Fl e \*(Ba Fl o Ic errexit 4051Exit (after executing the 4052.Dv ERR 4053trap) as soon as an error occurs or a command fails (i.e. exits with a 4054non-zero status). 4055This does not apply to commands whose exit status is 4056explicitly tested by a shell construct such as 4057.Ic if , 4058.Ic until , 4059.Ic while , 4060or 4061.Ic !\& 4062statements. 4063For 4064.Ic && 4065or 4066.Ic \*(Ba\*(Ba , 4067only the status of the last command is tested. 4068.It Fl f \*(Ba Fl o Ic noglob 4069Do not expand file name patterns. 4070.It Fl h \*(Ba Fl o Ic trackall 4071Create tracked aliases for all executed commands (see 4072.Sx Aliases 4073above). 4074Enabled by default for non-interactive shells. 4075.It Fl i \*(Ba Fl o Ic interactive 4076The shell is an interactive shell. 4077This option can only be used when the shell is invoked. 4078See above for a description of what this means. 4079.It Fl k \*(Ba Fl o Ic keyword 4080Parameter assignments are recognised anywhere in a command. 4081.It Fl l \*(Ba Fl o Ic login 4082The shell is a login shell. 4083This option can only be used when the shell is invoked. 4084See above for a description of what this means. 4085.It Fl m \*(Ba Fl o Ic monitor 4086Enable job control (default for interactive shells). 4087.It Fl n \*(Ba Fl o Ic noexec 4088Do not execute any commands. 4089Useful for checking the syntax of scripts 4090(ignored if interactive). 4091.It Fl p \*(Ba Fl o Ic privileged 4092The shell is a privileged shell. 4093It is set automatically if, when the shell starts, 4094the real UID or GID does not match 4095the effective UID (EUID) or GID (EGID), respectively. 4096See above for a description of what this means. 4097.It Fl r \*(Ba Fl o Ic restricted 4098The shell is a restricted shell. 4099This option can only be used when the shell is invoked. 4100See above for a description of what this means. 4101.It Fl s \*(Ba Fl o Ic stdin 4102If used when the shell is invoked, commands are read from standard input. 4103Set automatically if the shell is invoked with no arguments. 4104.Pp 4105When 4106.Fl s 4107is used with the 4108.Ic set 4109command it causes the specified arguments to be sorted before assigning them to 4110the positional parameters (or to array 4111.Ar name , 4112if 4113.Fl A 4114is used). 4115.It Fl U \*(Ba Fl o Ic utf8\-mode 4116Enable UTF-8 support in the 4117.Sx Emacs editing mode 4118and internal string handling functions. 4119This flag is disabled by default, but can be enabled by setting it on the 4120shell command line; is enabled automatically for interactive shells if 4121requested at compile time, your system supports 4122.Fn setlocale LC_CTYPE \&"" 4123and optionally 4124.Fn nl_langinfo CODESET , 4125or the 4126.Ev LC_ALL , 4127.Ev LC_CTYPE , 4128or 4129.Ev LANG 4130environment variables, 4131and at least one of these returns something that matches 4132.Dq UTF\-8 4133or 4134.Dq utf8 4135case-insensitively; for direct builtin calls depending on the 4136aforementioned environment variables; or for stdin or scripts, 4137if the input begins with a UTF-8 Byte Order Mark. 4138.It Fl u \*(Ba Fl o Ic nounset 4139Referencing of an unset parameter, other than 4140.Dq $@ 4141or 4142.Dq $* , 4143is treated as an error, unless one of the 4144.Ql \- , 4145.Ql + , 4146or 4147.Ql = 4148modifiers is used. 4149.It Fl v \*(Ba Fl o Ic verbose 4150Write shell input to standard error as it is read. 4151.It Fl X \*(Ba Fl o Ic markdirs 4152Mark directories with a trailing 4153.Ql / 4154during file name generation. 4155.It Fl x \*(Ba Fl o Ic xtrace 4156Print command trees when they are executed, preceded by 4157the value of 4158.Ev PS4 . 4159.It Fl o Ic bgnice 4160Background jobs are run with lower priority. 4161.It Fl o Ic braceexpand 4162Enable brace expansion (a.k.a. alternation). 4163This is enabled by default. 4164If disabled, tilde expansion after an equals sign is disabled as a side effect. 4165.It Fl o Ic emacs 4166Enable BRL emacs-like command-line editing (interactive shells only); see 4167.Sx Emacs editing mode . 4168.It Fl o Ic gmacs 4169Enable gmacs-like command-line editing (interactive shells only). 4170Currently identical to emacs editing except that transpose\-chars (\*(haT) acts 4171slightly differently. 4172.It Fl o Ic ignoreeof 4173The shell will not (easily) exit when end-of-file is read; 4174.Ic exit 4175must be used. 4176To avoid infinite loops, the shell will exit if 4177.Dv EOF 4178is read 13 times in a row. 4179.It Fl o Ic inherit\-xtrace 4180Do not reset 4181.Fl o Ic xtrace 4182upon entering functions. 4183This is enabled by default. 4184.It Fl o Ic nohup 4185Do not kill running jobs with a 4186.Dv SIGHUP 4187signal when a login shell exits. 4188Currently set by default, but this may 4189change in the future to be compatible with 4190.At 4191.Nm ksh , 4192which 4193doesn't have this option, but does send the 4194.Dv SIGHUP 4195signal. 4196.It Fl o Ic nolog 4197No effect. 4198In the original Korn shell, this prevents function definitions from 4199being stored in the history file. 4200.It Fl o Ic physical 4201Causes the 4202.Ic cd 4203and 4204.Ic pwd 4205commands to use 4206.Dq physical 4207(i.e. the filesystem's) 4208.Sq .. 4209directories instead of 4210.Dq logical 4211directories (i.e. the shell handles 4212.Sq .. , 4213which allows the user to be oblivious of symbolic links to directories). 4214Clear by default. 4215Note that setting this option does not affect the current value of the 4216.Ev PWD 4217parameter; only the 4218.Ic cd 4219command changes 4220.Ev PWD . 4221See the 4222.Ic cd 4223and 4224.Ic pwd 4225commands above for more details. 4226.It Fl o Ic pipefail 4227Make the exit status of a pipeline (before logically complementing) the 4228rightmost non-zero errorlevel, or zero if all commands exited with zero. 4229.It Fl o Ic posix 4230Enable a somewhat more 4231.Px 4232ish mode. 4233As a side effect, setting this flag turns off 4234.Ic braceexpand 4235mode, which can be turned back on manually, and 4236.Ic sh 4237mode. 4238.It Fl o Ic sh 4239Enable 4240.Pa /bin/sh 4241.Pq kludge 4242mode. 4243Automatically enabled if the basename of the shell invocation begins with 4244.Dq sh 4245and this autodetection feature is compiled in 4246.Pq not in MirBSD . 4247As a side effect, setting this flag turns off 4248.Ic braceexpand 4249mode, which can be turned back on manually, and 4250.Ic posix 4251mode. 4252.It Fl o Ic vi 4253Enable 4254.Xr vi 1 Ns -like 4255command-line editing (interactive shells only). 4256See 4257.Sx Vi editing mode 4258for documentation and limitations. 4259.It Fl o Ic vi\-esccomplete 4260In vi command-line editing, do command and file name completion when escape 4261(\*(ha[) is entered in command mode. 4262.It Fl o Ic vi\-tabcomplete 4263In vi command-line editing, do command and file name completion when tab (\*(haI) 4264is entered in insert mode. 4265This is the default. 4266.It Fl o Ic viraw 4267No effect. 4268In the original Korn shell, unless 4269.Ic viraw 4270was set, the vi command-line mode would let the 4271.Xr tty 4 4272driver do the work until ESC (\*(ha[) was entered. 4273.Nm 4274is always in viraw mode. 4275.El 4276.Pp 4277These options can also be used upon invocation of the shell. 4278The current set of 4279options (with single letter names) can be found in the parameter 4280.Sq $\- . 4281.Ic set Fl o 4282with no option name will list all the options and whether each is on or off; 4283.Ic set +o 4284will print the long names of all options that are currently on. 4285.Pp 4286Remaining arguments, if any, are positional parameters and are assigned, in 4287order, to the positional parameters (i.e. $1, $2, etc.). 4288If options end with 4289.Ql \-\- 4290and there are no remaining arguments, all positional parameters are cleared. 4291If no options or arguments are given, the values of all names are printed. 4292For unknown historical reasons, a lone 4293.Ql \- 4294option is treated specially \*(en it clears both the 4295.Fl v 4296and 4297.Fl x 4298options. 4299.Pp 4300.It Ic shift Op Ar number 4301The positional parameters 4302.Ar number Ns +1 , 4303.Ar number Ns +2 , 4304etc. are renamed to 4305.Sq 1 , 4306.Sq 2 , 4307etc. 4308.Ar number 4309defaults to 1. 4310.Pp 4311.It Ic sleep Ar seconds 4312Suspends execution for a minimum of the 4313.Ar seconds 4314specified as positive decimal value with an optional fractional part. 4315Signal delivery may continue execution earlier. 4316.Pp 4317.It Ic source Ar file Op Ar arg ... 4318Like 4319.Ic \&. Po Do dot Dc Pc , 4320except that the current working directory is appended to the 4321.Ev PATH 4322in GNU 4323.Nm bash 4324and 4325.Nm mksh . 4326In 4327.Nm ksh93 4328and 4329.Nm mksh , 4330this is implemented as a shell alias instead of a builtin. 4331.Pp 4332.It Ic suspend 4333Stops the shell as if it had received the suspend character from 4334the terminal. 4335It is not possible to suspend a login shell unless the parent process 4336is a member of the same terminal session but is a member of a different 4337process group. 4338As a general rule, if the shell was started by another shell or via 4339.Xr su 1 , 4340it can be suspended. 4341.Pp 4342.It Ic test Ar expression 4343.It Ic \&[ Ar expression Ic \&] 4344.Ic test 4345evaluates the 4346.Ar expression 4347and returns zero status if true, 1 if false, or greater than 1 if there 4348was an error. 4349It is normally used as the condition command of 4350.Ic if 4351and 4352.Ic while 4353statements. 4354Symbolic links are followed for all 4355.Ar file 4356expressions except 4357.Fl h 4358and 4359.Fl L . 4360.Pp 4361The following basic expressions are available: 4362.Bl -tag -width 17n 4363.It Fl a Ar file 4364.Ar file 4365exists. 4366.It Fl b Ar file 4367.Ar file 4368is a block special device. 4369.It Fl c Ar file 4370.Ar file 4371is a character special device. 4372.It Fl d Ar file 4373.Ar file 4374is a directory. 4375.It Fl e Ar file 4376.Ar file 4377exists. 4378.It Fl f Ar file 4379.Ar file 4380is a regular file. 4381.It Fl G Ar file 4382.Ar file Ns 's 4383group is the shell's effective group ID. 4384.It Fl g Ar file 4385.Ar file Ns 's 4386mode has the setgid bit set. 4387.It Fl H Ar file 4388.Ar file 4389is a context dependent directory (only useful on HP-UX). 4390.It Fl h Ar file 4391.Ar file 4392is a symbolic link. 4393.It Fl k Ar file 4394.Ar file Ns 's 4395mode has the 4396.Xr sticky 8 4397bit set. 4398.It Fl L Ar file 4399.Ar file 4400is a symbolic link. 4401.It Fl O Ar file 4402.Ar file Ns 's 4403owner is the shell's effective user ID. 4404.It Fl o Ar option 4405Shell 4406.Ar option 4407is set (see the 4408.Ic set 4409command above for a list of options). 4410As a non-standard extension, if the option starts with a 4411.Ql \&! , 4412the test is negated; the test always fails if 4413.Ar option 4414doesn't exist (so [ \-o foo \-o \-o !foo ] returns true if and only if option 4415.Ar foo 4416exists). 4417The same can be achieved with [ \-o ?foo ] like in 4418.At 4419.Nm ksh93 . 4420.Ar option 4421can also be the short flag led by either 4422.Ql \- 4423or 4424.Ql + 4425.Pq no logical negation , 4426for example 4427.Ql \-x 4428or 4429.Ql +x 4430instead of 4431.Ql xtrace . 4432.It Fl p Ar file 4433.Ar file 4434is a named pipe 4435.Pq Tn FIFO . 4436.It Fl r Ar file 4437.Ar file 4438exists and is readable. 4439.It Fl S Ar file 4440.Ar file 4441is a 4442.Xr unix 4 Ns -domain 4443socket. 4444.It Fl s Ar file 4445.Ar file 4446is not empty. 4447.It Fl t Ar fd 4448File descriptor 4449.Ar fd 4450is a 4451.Xr tty 4 4452device. 4453.It Fl u Ar file 4454.Ar file Ns 's 4455mode has the setuid bit set. 4456.It Fl w Ar file 4457.Ar file 4458exists and is writable. 4459.It Fl x Ar file 4460.Ar file 4461exists and is executable. 4462.It Ar file1 Fl nt Ar file2 4463.Ar file1 4464is newer than 4465.Ar file2 4466or 4467.Ar file1 4468exists and 4469.Ar file2 4470does not. 4471.It Ar file1 Fl ot Ar file2 4472.Ar file1 4473is older than 4474.Ar file2 4475or 4476.Ar file2 4477exists and 4478.Ar file1 4479does not. 4480.It Ar file1 Fl ef Ar file2 4481.Ar file1 4482is the same file as 4483.Ar file2 . 4484.It Ar string 4485.Ar string 4486has non-zero length. 4487.It Fl n Ar string 4488.Ar string 4489is not empty. 4490.It Fl z Ar string 4491.Ar string 4492is empty. 4493.It Ar string No = Ar string 4494Strings are equal. 4495.It Ar string No == Ar string 4496Strings are equal. 4497.It Ar string No \*(Gt Ar string 4498First string operand is greater than second string operand. 4499.It Ar string No \*(Lt Ar string 4500First string operand is less than second string operand. 4501.It Ar string No != Ar string 4502Strings are not equal. 4503.It Ar number Fl eq Ar number 4504Numbers compare equal. 4505.It Ar number Fl ne Ar number 4506Numbers compare not equal. 4507.It Ar number Fl ge Ar number 4508Numbers compare greater than or equal. 4509.It Ar number Fl gt Ar number 4510Numbers compare greater than. 4511.It Ar number Fl le Ar number 4512Numbers compare less than or equal. 4513.It Ar number Fl \< Ar number 4514Numbers compare less than. 4515.El 4516.Pp 4517The above basic expressions, in which unary operators have precedence over 4518binary operators, may be combined with the following operators (listed in 4519increasing order of precedence): 4520.Bd -literal -offset indent 4521expr \-o expr Logical OR. 4522expr \-a expr Logical AND. 4523! expr Logical NOT. 4524( expr ) Grouping. 4525.Ed 4526.Pp 4527Note that a number actually may be an arithmetic expression, such as 4528a mathematical term or the name of an integer variable: 4529.Bd -literal -offset indent 4530x=1; [ "x" \-eq 1 ] evaluates to true 4531.Ed 4532.Pp 4533Note that some special rules are applied (courtesy of 4534.Px 4535) if the number of arguments to 4536.Ic test 4537or inside the brackets 4538.Ic \&[ ... \&] 4539is less than five: if leading 4540.Ql \&! 4541arguments can be stripped such that only one to three arguments remain, 4542then the lowered comparison is executed; (thanks to XSI) parentheses 4543.Ic \e( ... \e) 4544lower four- and three-argument forms to two- and one-argument forms, 4545respectively; three-argument forms ultimately prefer binary operations, 4546followed by negation and parenthesis lowering; two- and four-argument forms 4547prefer negation followed by parenthesis; the one-argument form always implies 4548.Fl n . 4549.Pp 4550.Sy Note : 4551A common mistake is to use 4552.Dq if \&[ $foo = bar \&] 4553which fails if parameter 4554.Dq foo 4555is 4556.Dv NULL 4557or unset, if it has embedded spaces (i.e.\& 4558.Ev IFS 4559octets), or if it is a unary operator like 4560.Sq \&! 4561or 4562.Sq Fl n . 4563Use tests like 4564.Dq if \&[ x\&"$foo\&" = x"bar" \&] 4565instead, or the double-bracket operator 4566.Dq if \&[[ $foo = bar \&]] 4567or, to avoid pattern matching (see 4568.Ic \&[[ 4569above): 4570.Dq if \&[[ $foo = \&"$bar" \&]] 4571.Pp 4572The 4573.Ic \&[[ ... ]] 4574construct is not only more secure to use but also often faster. 4575.Pp 4576.It Xo 4577.Ic time 4578.Op Fl p 4579.Op Ar pipeline 4580.Xc 4581If a 4582.Ar pipeline 4583is given, the times used to execute the pipeline are reported. 4584If no pipeline 4585is given, then the user and system time used by the shell itself, and all the 4586commands it has run since it was started, are reported. 4587The times reported are the real time (elapsed time from start to finish), 4588the user CPU time (time spent running in user mode), and the system CPU time 4589(time spent running in kernel mode). 4590Times are reported to standard error; the format of the output is: 4591.Pp 4592.Dl "0m0.00s real 0m0.00s user 0m0.00s system" 4593.Pp 4594If the 4595.Fl p 4596option is given the output is slightly longer: 4597.Bd -literal -offset indent 4598real 0.00 4599user 0.00 4600sys 0.00 4601.Ed 4602.Pp 4603It is an error to specify the 4604.Fl p 4605option unless 4606.Ar pipeline 4607is a simple command. 4608.Pp 4609Simple redirections of standard error do not affect the output of the 4610.Ic time 4611command: 4612.Pp 4613.Dl $ time sleep 1 2\*(Gtafile 4614.Dl $ { time sleep 1; } 2\*(Gtafile 4615.Pp 4616Times for the first command do not go to 4617.Dq afile , 4618but those of the second command do. 4619.Pp 4620.It Ic times 4621Print the accumulated user and system times used both by the shell 4622and by processes that the shell started which have exited. 4623The format of the output is: 4624.Bd -literal -offset indent 46250m0.00s 0m0.00s 46260m0.00s 0m0.00s 4627.Ed 4628.Pp 4629.It Ic trap Op Ar handler signal ... 4630Sets a trap handler that is to be executed when any of the specified signals are 4631received. 4632.Ar handler 4633is either a 4634.Dv NULL 4635string, indicating the signals are to be ignored, a minus sign 4636.Pq Sq \- , 4637indicating that the default action is to be taken for the signals (see 4638.Xr signal 3 ) , 4639or a string containing shell commands to be evaluated and executed at the first 4640opportunity (i.e. when the current command completes, or before printing the 4641next 4642.Ev PS1 4643prompt) after receipt of one of the signals. 4644.Ar signal 4645is the name of a signal (e.g.\& 4646.Dv PIPE 4647or 4648.Dv ALRM ) 4649or the number of the signal (see the 4650.Ic kill \-l 4651command above). 4652.Pp 4653There are two special signals: 4654.Dv EXIT 4655(also known as 0) which is executed when the shell is about to exit, and 4656.Dv ERR , 4657which is executed after an error occurs (an error is something that would cause 4658the shell to exit if the 4659.Fl e 4660or 4661.Ic errexit 4662option were set \*(en see the 4663.Ic set 4664command above). 4665.Dv EXIT 4666handlers are executed in the environment of the last executed command. 4667Note 4668that for non-interactive shells, the trap handler cannot be changed for signals 4669that were ignored when the shell started. 4670.Pp 4671With no arguments, 4672.Ic trap 4673lists, as a series of 4674.Ic trap 4675commands, the current state of the traps that have been set since the shell 4676started. 4677Note that the output of 4678.Ic trap 4679cannot be usefully piped to another process (an artifact of the fact that 4680traps are cleared when subprocesses are created). 4681.Pp 4682The original Korn shell's 4683.Dv DEBUG 4684trap and the handling of 4685.Dv ERR 4686and 4687.Dv EXIT 4688traps in functions are not yet implemented. 4689.Pp 4690.It Ic true 4691A command that exits with a zero value. 4692.Pp 4693.It Xo 4694.Ic global 4695.Oo Op Ic +\-alpnrtUux 4696.Op Fl L Ns Op Ar n 4697.Op Fl R Ns Op Ar n 4698.Op Fl Z Ns Op Ar n 4699.Op Fl i Ns Op Ar n 4700.No \*(Ba Fl f Op Fl tux Oc 4701.Oo Ar name 4702.Op Ns = Ns Ar value 4703.Ar ... Oc 4704.Xc 4705.It Xo 4706.Ic typeset 4707.Oo Op Ic +\-alpnrtUux 4708.Op Fl LRZ Ns Op Ar n 4709.Op Fl i Ns Op Ar n 4710.No \*(Ba Fl f Op Fl tux Oc 4711.Oo Ar name 4712.Op Ns = Ns Ar value 4713.Ar ... Oc 4714.Xc 4715Display or set parameter attributes. 4716With no 4717.Ar name 4718arguments, parameter attributes are displayed; if no options are used, the 4719current attributes of all parameters are printed as 4720.Ic typeset 4721commands; if an option is given (or 4722.Ql \- 4723with no option letter), all parameters and their values with the specified 4724attributes are printed; if options are introduced with 4725.Ql + , 4726parameter values are not printed. 4727.Pp 4728If 4729.Ar name 4730arguments are given, the attributes of the named parameters are set 4731.Pq Ic \- 4732or cleared 4733.Pq Ic + . 4734Values for parameters may optionally be specified. 4735For 4736.Ar name Ns \&[*] , 4737the change affects the entire array, and no value may be specified. 4738.Pp 4739If 4740.Ic typeset 4741is used inside a function, any parameters specified are localised. 4742This is not done by the otherwise identical 4743.Ic global . 4744.Em Note : 4745This means that 4746.Nm No 's Ic global 4747command is 4748.Em not 4749equivalent to other programming languages' as it does not allow a 4750function called from another function to access a parameter at truly 4751global scope, but only prevents putting an accessed one into local scope. 4752.Pp 4753When 4754.Fl f 4755is used, 4756.Ic typeset 4757operates on the attributes of functions. 4758As with parameters, if no 4759.Ar name 4760arguments are given, 4761functions are listed with their values (i.e. definitions) unless 4762options are introduced with 4763.Ql + , 4764in which case only the function names are reported. 4765.Bl -tag -width Ds 4766.It Fl a 4767Indexed array attribute. 4768.It Fl f 4769Function mode. 4770Display or set functions and their attributes, instead of parameters. 4771.It Fl i Ns Op Ar n 4772Integer attribute. 4773.Ar n 4774specifies the base to use when displaying the integer (if not specified, the 4775base given in the first assignment is used). 4776Parameters with this attribute may 4777be assigned values containing arithmetic expressions. 4778.It Fl L Ns Op Ar n 4779Left justify attribute. 4780.Ar n 4781specifies the field width. 4782If 4783.Ar n 4784is not specified, the current width of a parameter (or the width of its first 4785assigned value) is used. 4786Leading whitespace (and zeros, if used with the 4787.Fl Z 4788option) is stripped. 4789If necessary, values are either truncated or space padded 4790to fit the field width. 4791.It Fl l 4792Lower case attribute. 4793All upper case characters in values are converted to lower case. 4794(In the original Korn shell, this parameter meant 4795.Dq long integer 4796when used with the 4797.Fl i 4798option.) 4799.It Fl n 4800Create a bound variable (name reference): any access to the variable 4801.Ar name 4802will access the variable 4803.Ar value 4804in the current scope (this is different from 4805.At 4806.Nm ksh93 ! ) 4807instead. 4808Also different from 4809.At 4810.Nm ksh93 4811is that 4812.Ar value 4813is lazily evaluated at the time 4814.Ar name 4815is accessed. 4816This can be used by functions to access variables whose names are 4817passed as parametres, instead of using 4818.Ic eval . 4819.It Fl p 4820Print complete 4821.Ic typeset 4822commands that can be used to re-create the attributes and values of 4823parameters. 4824.It Fl R Ns Op Ar n 4825Right justify attribute. 4826.Ar n 4827specifies the field width. 4828If 4829.Ar n 4830is not specified, the current width of a parameter (or the width of its first 4831assigned value) is used. 4832Trailing whitespace is stripped. 4833If necessary, values are either stripped of leading characters or space 4834padded to make them fit the field width. 4835.It Fl r 4836Read-only attribute. 4837Parameters with this attribute may not be assigned to or unset. 4838Once this attribute is set, it cannot be turned off. 4839.It Fl t 4840Tag attribute. 4841Has no meaning to the shell; provided for application use. 4842.Pp 4843For functions, 4844.Fl t 4845is the trace attribute. 4846When functions with the trace attribute are executed, the 4847.Ic xtrace 4848.Pq Fl x 4849shell option is temporarily turned on. 4850.It Fl U 4851Unsigned integer attribute. 4852Integers are printed as unsigned values (combine with the 4853.Fl i 4854option). 4855This option is not in the original Korn shell. 4856.It Fl u 4857Upper case attribute. 4858All lower case characters in values are converted to upper case. 4859(In the original Korn shell, this parameter meant 4860.Dq unsigned integer 4861when used with the 4862.Fl i 4863option which meant upper case letters would never be used for bases greater 4864than 10. 4865See the 4866.Fl U 4867option.) 4868.Pp 4869For functions, 4870.Fl u 4871is the undefined attribute. 4872See 4873.Sx Functions 4874above for the implications of this. 4875.It Fl x 4876Export attribute. 4877Parameters (or functions) are placed in the environment of 4878any executed commands. 4879Exported functions are not yet implemented. 4880.It Fl Z Ns Op Ar n 4881Zero fill attribute. 4882If not combined with 4883.Fl L , 4884this is the same as 4885.Fl R , 4886except zero padding is used instead of space padding. 4887For integers, the number instead of the base is padded. 4888.El 4889.Pp 4890If any of the 4891.\" long integer , 4892.Fl i , 4893.Fl L , 4894.Fl l , 4895.Fl R , 4896.Fl U , 4897.Fl u , 4898or 4899.Fl Z 4900options are changed, all others from this set are cleared, 4901unless they are also given on the same command line. 4902.Pp 4903.It Xo 4904.Ic ulimit 4905.Op Fl aBCcdefHilMmnOPpqrSsTtVvw 4906.Op Ar value 4907.Xc 4908Display or set process limits. 4909If no options are used, the file size limit 4910.Pq Fl f 4911is assumed. 4912.Ar value , 4913if specified, may be either an arithmetic expression or the word 4914.Dq unlimited . 4915The limits affect the shell and any processes created by the shell after a 4916limit is imposed. 4917Note that some systems may not allow limits to be increased 4918once they are set. 4919Also note that the types of limits available are system 4920dependent \*(en some systems have only the 4921.Fl f 4922limit. 4923.Bl -tag -width 5n 4924.It Fl a 4925Display all limits; unless 4926.Fl H 4927is used, soft limits are displayed. 4928.It Fl B Ar n 4929Set the socket buffer size to 4930.Ar n 4931kibibytes. 4932.It Fl C Ar n 4933Set the number of cached threads to 4934.Ar n . 4935.It Fl c Ar n 4936Impose a size limit of 4937.Ar n 4938blocks on the size of core dumps. 4939.It Fl d Ar n 4940Impose a size limit of 4941.Ar n 4942kibibytes on the size of the data area. 4943.It Fl e Ar n 4944Set the maximum niceness to 4945.Ar n . 4946.It Fl f Ar n 4947Impose a size limit of 4948.Ar n 4949blocks on files written by the shell and its child processes (files of any 4950size may be read). 4951.It Fl H 4952Set the hard limit only (the default is to set both hard and soft limits). 4953.It Fl i Ar n 4954Set the number of pending signals to 4955.Ar n . 4956.It Fl l Ar n 4957Impose a limit of 4958.Ar n 4959kibibytes on the amount of locked (wired) physical memory. 4960.It Fl M Ar n 4961Set the AIO locked memory to 4962.Ar n 4963kibibytes. 4964.It Fl m Ar n 4965Impose a limit of 4966.Ar n 4967kibibytes on the amount of physical memory used. 4968.It Fl n Ar n 4969Impose a limit of 4970.Ar n 4971file descriptors that can be open at once. 4972.It Fl O Ar n 4973Set the number of AIO operations to 4974.Ar n . 4975.It Fl P Ar n 4976Limit the number of threads per process to 4977.Ar n . 4978.It Fl p Ar n 4979Impose a limit of 4980.Ar n 4981processes that can be run by the user at any one time. 4982.It Fl q Ar n 4983Limit the size of 4984.Tn POSIX 4985message queues to 4986.Ar n 4987bytes. 4988.It Fl r Ar n 4989Set the maximum real-time priority to 4990.Ar n . 4991.It Fl S 4992Set the soft limit only (the default is to set both hard and soft limits). 4993.It Fl s Ar n 4994Impose a size limit of 4995.Ar n 4996kibibytes on the size of the stack area. 4997.It Fl T Ar n 4998Impose a time limit of 4999.Ar n 5000real seconds to be used by each process. 5001.It Fl t Ar n 5002Impose a time limit of 5003.Ar n 5004CPU seconds spent in user mode to be used by each process. 5005.It Fl V Ar n 5006Set the number of vnode monitors on Haiku to 5007.Ar n . 5008.It Fl v Ar n 5009Impose a limit of 5010.Ar n 5011kibibytes on the amount of virtual memory (address space) used. 5012.It Fl w Ar n 5013Impose a limit of 5014.Ar n 5015kibibytes on the amount of swap space used. 5016.El 5017.Pp 5018As far as 5019.Ic ulimit 5020is concerned, a block is 512 bytes. 5021.Pp 5022.It Xo 5023.Ic umask 5024.Op Fl S 5025.Op Ar mask 5026.Xc 5027Display or set the file permission creation mask, or umask (see 5028.Xr umask 2 ) . 5029If the 5030.Fl S 5031option is used, the mask displayed or set is symbolic; otherwise, it is an 5032octal number. 5033.Pp 5034Symbolic masks are like those used by 5035.Xr chmod 1 . 5036When used, they describe what permissions may be made available (as opposed to 5037octal masks in which a set bit means the corresponding bit is to be cleared). 5038For example, 5039.Dq ug=rwx,o= 5040sets the mask so files will not be readable, writable, or executable by 5041.Dq others , 5042and is equivalent (on most systems) to the octal mask 5043.Dq 007 . 5044.Pp 5045.It Xo 5046.Ic unalias 5047.Op Fl adt 5048.Op Ar name ... 5049.Xc 5050The aliases for the given names are removed. 5051If the 5052.Fl a 5053option is used, all aliases are removed. 5054If the 5055.Fl t 5056or 5057.Fl d 5058options are used, the indicated operations are carried out on tracked or 5059directory aliases, respectively. 5060.Pp 5061.It Xo 5062.Ic unset 5063.Op Fl fv 5064.Ar parameter ... 5065.Xc 5066Unset the named parameters 5067.Po 5068.Fl v , 5069the default 5070.Pc 5071or functions 5072.Pq Fl f . 5073With 5074.Ar parameter Ns \&[*] , 5075attributes are kept, only values are unset. 5076.Pp 5077The exit status is non-zero if any of the parameters have the read-only 5078attribute set, zero otherwise. 5079.Pp 5080.It Ic wait Op Ar job ... 5081Wait for the specified job(s) to finish. 5082The exit status of 5083.Ic wait 5084is that of the last specified job; if the last job is killed by a signal, the 5085exit status is 128 + the number of the signal (see 5086.Ic kill \-l Ar exit-status 5087above); if the last specified job can't be found (because it never existed, or 5088had already finished), the exit status of 5089.Ic wait 5090is 127. 5091See 5092.Sx Job control 5093below for the format of 5094.Ar job . 5095.Ic wait 5096will return if a signal for which a trap has been set is received, or if a 5097.Dv SIGHUP , 5098.Dv SIGINT , 5099or 5100.Dv SIGQUIT 5101signal is received. 5102.Pp 5103If no jobs are specified, 5104.Ic wait 5105waits for all currently running jobs (if any) to finish and exits with a zero 5106status. 5107If job monitoring is enabled, the completion status of jobs is printed 5108(this is not the case when jobs are explicitly specified). 5109.Pp 5110.It Xo 5111.Ic whence 5112.Op Fl pv 5113.Op Ar name ... 5114.Xc 5115For each 5116.Ar name , 5117the type of command is listed (reserved word, built-in, alias, 5118function, tracked alias, or executable). 5119If the 5120.Fl p 5121option is used, a path search is performed even if 5122.Ar name 5123is a reserved word, alias, etc. 5124Without the 5125.Fl v 5126option, 5127.Ic whence 5128is similar to 5129.Ic command Fl v 5130except that 5131.Ic whence 5132will find reserved words and won't print aliases as alias commands. 5133With the 5134.Fl v 5135option, 5136.Ic whence 5137is the same as 5138.Ic command Fl V . 5139Note that for 5140.Ic whence , 5141the 5142.Fl p 5143option does not affect the search path used, as it does for 5144.Ic command . 5145If the type of one or more of the names could not be determined, the exit 5146status is non-zero. 5147.El 5148.Ss Job control 5149Job control refers to the shell's ability to monitor and control jobs which 5150are processes or groups of processes created for commands or pipelines. 5151At a minimum, the shell keeps track of the status of the background (i.e.\& 5152asynchronous) jobs that currently exist; this information can be displayed 5153using the 5154.Ic jobs 5155commands. 5156If job control is fully enabled (using 5157.Ic set \-m 5158or 5159.Ic set \-o monitor ) , 5160as it is for interactive shells, the processes of a job are placed in their 5161own process group. 5162Foreground jobs can be stopped by typing the suspend 5163character from the terminal (normally \*(haZ), jobs can be restarted in either the 5164foreground or background using the 5165.Ic fg 5166and 5167.Ic bg 5168commands, and the state of the terminal is saved or restored when a foreground 5169job is stopped or restarted, respectively. 5170.Pp 5171Note that only commands that create processes (e.g. asynchronous commands, 5172subshell commands, and non-built-in, non-function commands) can be stopped; 5173commands like 5174.Ic read 5175cannot be. 5176.Pp 5177When a job is created, it is assigned a job number. 5178For interactive shells, this number is printed inside 5179.Dq \&[..] , 5180followed by the process IDs of the processes in the job when an asynchronous 5181command is run. 5182A job may be referred to in the 5183.Ic bg , 5184.Ic fg , 5185.Ic jobs , 5186.Ic kill , 5187and 5188.Ic wait 5189commands either by the process ID of the last process in the command pipeline 5190(as stored in the 5191.Ic $!\& 5192parameter) or by prefixing the job number with a percent 5193sign 5194.Pq Sq % . 5195Other percent sequences can also be used to refer to jobs: 5196.Bl -tag -width "%+ x %% x %XX" 5197.It %+ \*(Ba %% \*(Ba % 5198The most recently stopped job, or, if there are no stopped jobs, the oldest 5199running job. 5200.It %\- 5201The job that would be the 5202.Ic %+ 5203job if the latter did not exist. 5204.It % Ns Ar n 5205The job with job number 5206.Ar n . 5207.It %? Ns Ar string 5208The job with its command containing the string 5209.Ar string 5210(an error occurs if multiple jobs are matched). 5211.It % Ns Ar string 5212The job with its command starting with the string 5213.Ar string 5214(an error occurs if multiple jobs are matched). 5215.El 5216.Pp 5217When a job changes state (e.g. a background job finishes or foreground job is 5218stopped), the shell prints the following status information: 5219.Pp 5220.D1 [ Ns Ar number ] Ar flag status command 5221.Pp 5222where... 5223.Bl -tag -width "command" 5224.It Ar number 5225is the job number of the job; 5226.It Ar flag 5227is the 5228.Ql + 5229or 5230.Ql \- 5231character if the job is the 5232.Ic %+ 5233or 5234.Ic %\- 5235job, respectively, or space if it is neither; 5236.It Ar status 5237indicates the current state of the job and can be: 5238.Bl -tag -width "RunningXX" 5239.It Done Op Ar number 5240The job exited. 5241.Ar number 5242is the exit status of the job which is omitted if the status is zero. 5243.It Running 5244The job has neither stopped nor exited (note that running does not necessarily 5245mean consuming CPU time \*(en 5246the process could be blocked waiting for some event). 5247.It Stopped Op Ar signal 5248The job was stopped by the indicated 5249.Ar signal 5250(if no signal is given, the job was stopped by 5251.Dv SIGTSTP ) . 5252.It Ar signal-description Op Dq core dumped 5253The job was killed by a signal (e.g. memory fault, hangup); use 5254.Ic kill \-l 5255for a list of signal descriptions. 5256The 5257.Dq core dumped 5258message indicates the process created a core file. 5259.El 5260.It Ar command 5261is the command that created the process. 5262If there are multiple processes in 5263the job, each process will have a line showing its 5264.Ar command 5265and possibly its 5266.Ar status , 5267if it is different from the status of the previous process. 5268.El 5269.Pp 5270When an attempt is made to exit the shell while there are jobs in the stopped 5271state, the shell warns the user that there are stopped jobs and does not exit. 5272If another attempt is immediately made to exit the shell, the stopped jobs are 5273sent a 5274.Dv SIGHUP 5275signal and the shell exits. 5276Similarly, if the 5277.Ic nohup 5278option is not set and there are running jobs when an attempt is made to exit 5279a login shell, the shell warns the user and does not exit. 5280If another attempt 5281is immediately made to exit the shell, the running jobs are sent a 5282.Dv SIGHUP 5283signal and the shell exits. 5284.Ss Interactive input line editing 5285The shell supports three modes of reading command lines from a 5286.Xr tty 4 5287in an interactive session, controlled by the 5288.Ic emacs , 5289.Ic gmacs , 5290and 5291.Ic vi 5292options (at most one of these can be set at once). 5293The default is 5294.Ic emacs . 5295Editing modes can be set explicitly using the 5296.Ic set 5297built-in. 5298If none of these options are enabled, 5299the shell simply reads lines using the normal 5300.Xr tty 4 5301driver. 5302If the 5303.Ic emacs 5304or 5305.Ic gmacs 5306option is set, the shell allows emacs-like editing of the command; similarly, 5307if the 5308.Ic vi 5309option is set, the shell allows vi-like editing of the command. 5310These modes are described in detail in the following sections. 5311.Pp 5312In these editing modes, if a line is longer than the screen width (see the 5313.Ev COLUMNS 5314parameter), 5315a 5316.Ql \*(Gt , 5317.Ql + , 5318or 5319.Ql \*(Lt 5320character is displayed in the last column indicating that there are more 5321characters after, before and after, or before the current position, 5322respectively. 5323The line is scrolled horizontally as necessary. 5324.Pp 5325Completed lines are pushed into the history, unless they begin with an 5326IFS octet or IFS white space, or are the same as the previous line. 5327.Ss Emacs editing mode 5328When the 5329.Ic emacs 5330option is set, interactive input line editing is enabled. 5331Warning: This mode is 5332slightly different from the emacs mode in the original Korn shell. 5333In this mode, various editing commands 5334(typically bound to one or more control characters) cause immediate actions 5335without waiting for a newline. 5336Several editing commands are bound to particular 5337control characters when the shell is invoked; these bindings can be changed 5338using the 5339.Ic bind 5340command. 5341.Pp 5342The following is a list of available editing commands. 5343Each description starts with the name of the command, 5344suffixed with a colon; 5345an 5346.Op Ar n 5347(if the command can be prefixed with a count); and any keys the command is 5348bound to by default, written using caret notation 5349e.g. the ASCII ESC character is written as \*(ha[. 5350These control sequences are not case sensitive. 5351A count prefix for a command is entered using the sequence 5352.Pf \*(ha[ Ns Ar n , 5353where 5354.Ar n 5355is a sequence of 1 or more digits. 5356Unless otherwise specified, if a count is 5357omitted, it defaults to 1. 5358.Pp 5359Note that editing command names are used only with the 5360.Ic bind 5361command. 5362Furthermore, many editing commands are useful only on terminals with 5363a visible cursor. 5364The default bindings were chosen to resemble corresponding 5365Emacs key bindings. 5366The user's 5367.Xr tty 4 5368characters (e.g.\& 5369.Dv ERASE ) 5370are bound to 5371reasonable substitutes and override the default bindings. 5372.Bl -tag -width Ds 5373.It abort: \*(haC, \*(haG 5374Abort the current command, empty the line buffer and 5375set the exit state to interrupted. 5376.It auto\-insert: Op Ar n 5377Simply causes the character to appear as literal input. 5378Most ordinary characters are bound to this. 5379.It Xo backward\-char: 5380.Op Ar n 5381.No \*(haB , \*(haXD , ANSI-CurLeft 5382.Xc 5383Moves the cursor backward 5384.Ar n 5385characters. 5386.It Xo backward\-word: 5387.Op Ar n 5388.No \*(ha[b , ANSI-Ctrl-CurLeft , ANSI-Alt-CurLeft 5389.Xc 5390Moves the cursor backward to the beginning of the word; words consist of 5391alphanumerics, underscore 5392.Pq Sq _ , 5393and dollar sign 5394.Pq Sq $ 5395characters. 5396.It beginning\-of\-history: \*(ha[\*(Lt 5397Moves to the beginning of the history. 5398.It beginning\-of\-line: \*(haA, ANSI-Home 5399Moves the cursor to the beginning of the edited input line. 5400.It Xo capitalise\-word: 5401.Op Ar n 5402.No \*(ha[C , \*(ha[c 5403.Xc 5404Uppercase the first character in the next 5405.Ar n 5406words, leaving the cursor past the end of the last word. 5407.It clear\-screen: \*(ha[\*(haL 5408Prints a compile-time configurable sequence to clear the screen and home 5409the cursor, redraws the entire prompt and the currently edited input line. 5410The default sequence works for almost all standard terminals. 5411.It comment: \*(ha[# 5412If the current line does not begin with a comment character, one is added at 5413the beginning of the line and the line is entered (as if return had been 5414pressed); otherwise, the existing comment characters are removed and the cursor 5415is placed at the beginning of the line. 5416.It complete: \*(ha[\*(ha[ 5417Automatically completes as much as is unique of the command name or the file 5418name containing the cursor. 5419If the entire remaining command or file name is 5420unique, a space is printed after its completion, unless it is a directory name 5421in which case 5422.Ql / 5423is appended. 5424If there is no command or file name with the current partial word 5425as its prefix, a bell character is output (usually causing a beep to be 5426sounded). 5427.It complete\-command: \*(haX\*(ha[ 5428Automatically completes as much as is unique of the command name having the 5429partial word up to the cursor as its prefix, as in the 5430.Ic complete 5431command above. 5432.It complete\-file: \*(ha[\*(haX 5433Automatically completes as much as is unique of the file name having the 5434partial word up to the cursor as its prefix, as in the 5435.Ic complete 5436command described above. 5437.It complete\-list: \*(haI, \*(ha[= 5438Complete as much as is possible of the current word, 5439and list the possible completions for it. 5440If only one completion is possible, 5441match as in the 5442.Ic complete 5443command above. 5444Note that \*(haI is usually generated by the TAB (tabulator) key. 5445.It Xo delete\-char\-backward: 5446.Op Ar n 5447.No ERASE , \*(ha? , \*(haH 5448.Xc 5449Deletes 5450.Ar n 5451characters before the cursor. 5452.It Xo delete\-char\-forward: 5453.Op Ar n 5454.No ANSI-Del 5455.Xc 5456Deletes 5457.Ar n 5458characters after the cursor. 5459.It Xo delete\-word\-backward: 5460.Op Ar n 5461.No WERASE , \*(ha[\*(ha? , \*(ha[\*(haH , \*(ha[h 5462.Xc 5463Deletes 5464.Ar n 5465words before the cursor. 5466.It Xo delete\-word\-forward: 5467.Op Ar n 5468.No \*(ha[d 5469.Xc 5470Deletes characters after the cursor up to the end of 5471.Ar n 5472words. 5473.It Xo down\-history: 5474.Op Ar n 5475.No \*(haN , \*(haXB , ANSI-CurDown 5476.Xc 5477Scrolls the history buffer forward 5478.Ar n 5479lines (later). 5480Each input line originally starts just after the last entry 5481in the history buffer, so 5482.Ic down\-history 5483is not useful until either 5484.Ic search\-history , 5485.Ic search\-history\-up 5486or 5487.Ic up\-history 5488has been performed. 5489.It Xo downcase\-word: 5490.Op Ar n 5491.No \*(ha[L , \*(ha[l 5492.Xc 5493Lowercases the next 5494.Ar n 5495words. 5496.It Xo edit\-line: 5497.Op Ar n 5498.No \*(haXe 5499.Xc 5500Edit line 5501.Ar n 5502or the current line, if not specified, interactively. 5503The actual command executed is 5504.Ic fc \-e ${VISUAL:\-${EDITOR:\-vi}} Ar n . 5505.It end\-of\-history: \*(ha[\*(Gt 5506Moves to the end of the history. 5507.It end\-of\-line: \*(haE, ANSI-End 5508Moves the cursor to the end of the input line. 5509.It eot: \*(ha_ 5510Acts as an end-of-file; this is useful because edit-mode input disables 5511normal terminal input canonicalization. 5512.It Xo eot\-or\-delete: 5513.Op Ar n 5514.No \*(haD 5515.Xc 5516Acts as 5517.Ic eot 5518if alone on a line; otherwise acts as 5519.Ic delete\-char\-forward . 5520.It error: (not bound) 5521Error (ring the bell). 5522.It exchange\-point\-and\-mark: \*(haX\*(haX 5523Places the cursor where the mark is and sets the mark to where the cursor was. 5524.It expand\-file: \*(ha[* 5525Appends a 5526.Ql * 5527to the current word and replaces the word with the result of performing file 5528globbing on the word. 5529If no files match the pattern, the bell is rung. 5530.It Xo forward\-char: 5531.Op Ar n 5532.No \*(haF , \*(haXC , ANSI-CurRight 5533.Xc 5534Moves the cursor forward 5535.Ar n 5536characters. 5537.It Xo forward\-word: 5538.Op Ar n 5539.No \*(ha[f , ANSI-Ctrl-CurRight , ANSI-Alt-CurRight 5540.Xc 5541Moves the cursor forward to the end of the 5542.Ar n Ns th 5543word. 5544.It Xo goto\-history: 5545.Op Ar n 5546.No \*(ha[g 5547.Xc 5548Goes to history number 5549.Ar n . 5550.It kill\-line: KILL 5551Deletes the entire input line. 5552.It kill\-region: \*(haW 5553Deletes the input between the cursor and the mark. 5554.It Xo kill\-to\-eol: 5555.Op Ar n 5556.No \*(haK 5557.Xc 5558Deletes the input from the cursor to the end of the line if 5559.Ar n 5560is not specified; otherwise deletes characters between the cursor and column 5561.Ar n . 5562.It list: \*(ha[? 5563Prints a sorted, columnated list of command names or file names (if any) that 5564can complete the partial word containing the cursor. 5565Directory names have 5566.Ql / 5567appended to them. 5568.It list\-command: \*(haX? 5569Prints a sorted, columnated list of command names (if any) that can complete 5570the partial word containing the cursor. 5571.It list\-file: \*(haX\*(haY 5572Prints a sorted, columnated list of file names (if any) that can complete the 5573partial word containing the cursor. 5574File type indicators are appended as described under 5575.Ic list 5576above. 5577.It newline: \*(haJ , \*(haM 5578Causes the current input line to be processed by the shell. 5579The current cursor position may be anywhere on the line. 5580.It newline\-and\-next: \*(haO 5581Causes the current input line to be processed by the shell, and the next line 5582from history becomes the current line. 5583This is only useful after an 5584.Ic up\-history , 5585.Ic search\-history 5586or 5587.Ic search\-history\-up . 5588.It no\-op: QUIT 5589This does nothing. 5590.It prefix\-1: \*(ha[ 5591Introduces a 2-character command sequence. 5592.It prefix\-2: \*(haX , \*(ha[[ , \*(ha[O 5593Introduces a 2-character command sequence. 5594.It Xo prev\-hist\-word: 5595.Op Ar n 5596.No \*(ha[. , \*(ha[_ 5597.Xc 5598The last word, or, if given, the 5599.Ar n Ns th 5600word (zero-based) of the previous (on repeated execution, second-last, 5601third-last, etc.) command is inserted at the cursor. 5602Use of this editing command trashes the mark. 5603.It quote: \*(ha\*(ha , \*(haV 5604The following character is taken literally rather than as an editing command. 5605.It redraw: \*(haL 5606Reprints the last line of the prompt string and the current input line 5607on a new line. 5608.It Xo search\-character\-backward: 5609.Op Ar n 5610.No \*(ha[\*(ha] 5611.Xc 5612Search backward in the current line for the 5613.Ar n Ns th 5614occurrence of the next character typed. 5615.It Xo search\-character\-forward: 5616.Op Ar n 5617.No \*(ha] 5618.Xc 5619Search forward in the current line for the 5620.Ar n Ns th 5621occurrence of the next character typed. 5622.It search\-history: \*(haR 5623Enter incremental search mode. 5624The internal history list is searched 5625backwards for commands matching the input. 5626An initial 5627.Ql \*(ha 5628in the search string anchors the search. 5629The escape key will leave search mode. 5630Other commands, including sequences of escape as 5631.Ic prefix\-1 5632followed by a 5633.Ic prefix\-1 5634or 5635.Ic prefix\-2 5636key will be executed after leaving search mode. 5637The 5638.Ic abort Pq \*(haG 5639command will restore the input line before search started. 5640Successive 5641.Ic search\-history 5642commands continue searching backward to the next previous occurrence of the 5643pattern. 5644The history buffer retains only a finite number of lines; the oldest 5645are discarded as necessary. 5646.It search\-history\-up: ANSI-PgUp 5647Search backwards through the history buffer for commands whose beginning match 5648the portion of the input line before the cursor. 5649When used on an empty line, this has the same effect as 5650.Ic up\-history . 5651.It search\-history\-down: ANSI-PgDn 5652Search forwards through the history buffer for commands whose beginning match 5653the portion of the input line before the cursor. 5654When used on an empty line, this has the same effect as 5655.Ic down\-history . 5656This is only useful after an 5657.Ic up\-history , 5658.Ic search\-history 5659or 5660.Ic search\-history\-up . 5661.It set\-mark\-command: \*(ha[ Ns Aq space 5662Set the mark at the cursor position. 5663.It transpose\-chars: \*(haT 5664If at the end of line, or if the 5665.Ic gmacs 5666option is set, this exchanges the two previous characters; otherwise, it 5667exchanges the previous and current characters and moves the cursor one 5668character to the right. 5669.It Xo up\-history: 5670.Op Ar n 5671.No \*(haP , \*(haXA , ANSI-CurUp 5672.Xc 5673Scrolls the history buffer backward 5674.Ar n 5675lines (earlier). 5676.It Xo upcase\-word: 5677.Op Ar n 5678.No \*(ha[U , \*(ha[u 5679.Xc 5680Uppercase the next 5681.Ar n 5682words. 5683.It version: \*(ha[\*(haV 5684Display the version of 5685.Nm mksh . 5686The current edit buffer is restored as soon as a key is pressed. 5687The restoring keypress is processed, unless it is a space. 5688.It yank: \*(haY 5689Inserts the most recently killed text string at the current cursor position. 5690.It yank\-pop: \*(ha[y 5691Immediately after a 5692.Ic yank , 5693replaces the inserted text string with the next previously killed text string. 5694.El 5695.Ss Vi editing mode 5696.Em Note: 5697The vi command-line editing mode is orphaned, yet still functional. 5698It is 8-bit clean but specifically does not support UTF-8 or MBCS. 5699.Pp 5700The vi command-line editor in 5701.Nm 5702has basically the same commands as the 5703.Xr vi 1 5704editor with the following exceptions: 5705.Bl -bullet 5706.It 5707You start out in insert mode. 5708.It 5709There are file name and command completion commands: 5710=, \e, *, \*(haX, \*(haE, \*(haF, and, optionally, 5711.Aq tab 5712and 5713.Aq esc . 5714.It 5715The 5716.Ic _ 5717command is different (in 5718.Nm mksh , 5719it is the last argument command; in 5720.Xr vi 1 5721it goes to the start of the current line). 5722.It 5723The 5724.Ic / 5725and 5726.Ic G 5727commands move in the opposite direction to the 5728.Ic j 5729command. 5730.It 5731Commands which don't make sense in a single line editor are not available 5732(e.g. screen movement commands and 5733.Xr ex 1 Ns -style 5734colon 5735.Pq Ic \&: 5736commands). 5737.El 5738.Pp 5739Like 5740.Xr vi 1 , 5741there are two modes: 5742.Dq insert 5743mode and 5744.Dq command 5745mode. 5746In insert mode, most characters are simply put in the buffer at the 5747current cursor position as they are typed; however, some characters are 5748treated specially. 5749In particular, the following characters are taken from current 5750.Xr tty 4 5751settings 5752(see 5753.Xr stty 1 ) 5754and have their usual meaning (normal values are in parentheses): kill (\*(haU), 5755erase (\*(ha?), werase (\*(haW), eof (\*(haD), intr (\*(haC), and quit (\*(ha\e). 5756In addition to 5757the above, the following characters are also treated specially in insert mode: 5758.Bl -tag -width XJXXXXM 5759.It \*(haE 5760Command and file name enumeration (see below). 5761.It \*(haF 5762Command and file name completion (see below). 5763If used twice in a row, the 5764list of possible completions is displayed; if used a third time, the completion 5765is undone. 5766.It \*(haH 5767Erases previous character. 5768.It \*(haJ \*(Ba \*(haM 5769End of line. 5770The current line is read, parsed, and executed by the shell. 5771.It \*(haV 5772Literal next. 5773The next character typed is not treated specially (can be used 5774to insert the characters being described here). 5775.It \*(haX 5776Command and file name expansion (see below). 5777.It Aq esc 5778Puts the editor in command mode (see below). 5779.It Aq tab 5780Optional file name and command completion (see 5781.Ic \*(haF 5782above), enabled with 5783.Ic set \-o vi\-tabcomplete . 5784.El 5785.Pp 5786In command mode, each character is interpreted as a command. 5787Characters that 5788don't correspond to commands, are illegal combinations of commands, or are 5789commands that can't be carried out, all cause beeps. 5790In the following command descriptions, an 5791.Op Ar n 5792indicates the command may be prefixed by a number (e.g.\& 5793.Ic 10l 5794moves right 10 characters); if no number prefix is used, 5795.Ar n 5796is assumed to be 1 unless otherwise specified. 5797The term 5798.Dq current position 5799refers to the position between the cursor and the character preceding the 5800cursor. 5801A 5802.Dq word 5803is a sequence of letters, digits, and underscore characters or a sequence of 5804non-letter, non-digit, non-underscore, and non-whitespace characters (e.g.\& 5805.Dq ab2*&\*(ha 5806contains two words) and a 5807.Dq big-word 5808is a sequence of non-whitespace characters. 5809.Pp 5810Special 5811.Nm 5812vi commands: 5813.Pp 5814The following commands are not in, or are different from, the normal vi file 5815editor: 5816.Bl -tag -width 10n 5817.It Xo 5818.Oo Ar n Oc Ns _ 5819.Xc 5820Insert a space followed by the 5821.Ar n Ns th 5822big-word from the last command in the history at the current position and enter 5823insert mode; if 5824.Ar n 5825is not specified, the last word is inserted. 5826.It # 5827Insert the comment character 5828.Pq Sq # 5829at the start of the current line and return the line to the shell (equivalent 5830to 5831.Ic I#\*(haJ ) . 5832.It Xo 5833.Oo Ar n Oc Ns g 5834.Xc 5835Like 5836.Ic G , 5837except if 5838.Ar n 5839is not specified, it goes to the most recent remembered line. 5840.It Xo 5841.Oo Ar n Oc Ns v 5842.Xc 5843Edit line 5844.Ar n 5845using the 5846.Xr vi 1 5847editor; if 5848.Ar n 5849is not specified, the current line is edited. 5850The actual command executed is 5851.Ic fc \-e ${VISUAL:\-${EDITOR:\-vi}} Ar n . 5852.It * and \*(haX 5853Command or file name expansion is applied to the current big-word (with an 5854appended 5855.Ql * 5856if the word contains no file globbing characters) \*(en the big-word is replaced 5857with the resulting words. 5858If the current big-word is the first on the line 5859or follows one of the characters 5860.Ql \&; , 5861.Ql \*(Ba , 5862.Ql & , 5863.Ql \&( , 5864or 5865.Ql \&) , 5866and does not contain a slash 5867.Pq Sq / , 5868then command expansion is done; otherwise file name expansion is done. 5869Command expansion will match the big-word against all aliases, functions, and 5870built-in commands as well as any executable files found by searching the 5871directories in the 5872.Ev PATH 5873parameter. 5874File name expansion matches the big-word against the files in the 5875current directory. 5876After expansion, the cursor is placed just past the last 5877word and the editor is in insert mode. 5878.It Xo 5879.Oo Ar n Oc Ns \e , 5880.Oo Ar n Oc Ns \*(haF , 5881.Oo Ar n Oc Ns Aq tab , 5882.No and 5883.Oo Ar n Oc Ns Aq esc 5884.Xc 5885Command/file name completion. 5886Replace the current big-word with the 5887longest unique match obtained after performing command and file name expansion. 5888.Aq tab 5889is only recognised if the 5890.Ic vi\-tabcomplete 5891option is set, while 5892.Aq esc 5893is only recognised if the 5894.Ic vi\-esccomplete 5895option is set (see 5896.Ic set \-o ) . 5897If 5898.Ar n 5899is specified, the 5900.Ar n Ns th 5901possible completion is selected (as reported by the command/file name 5902enumeration command). 5903.It = and \*(haE 5904Command/file name enumeration. 5905List all the commands or files that match the current big-word. 5906.It \*(haV 5907Display the version of 5908.Nm mksh . 5909The current edit buffer is restored as soon as a key is pressed. 5910The restoring keypress is ignored. 5911.It @ Ns Ar c 5912Macro expansion. 5913Execute the commands found in the alias 5914.Ar c . 5915.El 5916.Pp 5917Intra-line movement commands: 5918.Bl -tag -width Ds 5919.It Xo 5920.Oo Ar n Oc Ns h and 5921.Oo Ar n Oc Ns \*(haH 5922.Xc 5923Move left 5924.Ar n 5925characters. 5926.It Xo 5927.Oo Ar n Oc Ns l and 5928.Oo Ar n Oc Ns Aq space 5929.Xc 5930Move right 5931.Ar n 5932characters. 5933.It 0 5934Move to column 0. 5935.It \*(ha 5936Move to the first non-whitespace character. 5937.It Xo 5938.Oo Ar n Oc Ns \*(Ba 5939.Xc 5940Move to column 5941.Ar n . 5942.It $ 5943Move to the last character. 5944.It Xo 5945.Oo Ar n Oc Ns b 5946.Xc 5947Move back 5948.Ar n 5949words. 5950.It Xo 5951.Oo Ar n Oc Ns B 5952.Xc 5953Move back 5954.Ar n 5955big-words. 5956.It Xo 5957.Oo Ar n Oc Ns e 5958.Xc 5959Move forward to the end of the word, 5960.Ar n 5961times. 5962.It Xo 5963.Oo Ar n Oc Ns E 5964.Xc 5965Move forward to the end of the big-word, 5966.Ar n 5967times. 5968.It Xo 5969.Oo Ar n Oc Ns w 5970.Xc 5971Move forward 5972.Ar n 5973words. 5974.It Xo 5975.Oo Ar n Oc Ns W 5976.Xc 5977Move forward 5978.Ar n 5979big-words. 5980.It % 5981Find match. 5982The editor looks forward for the nearest parenthesis, bracket, or 5983brace and then moves the cursor to the matching parenthesis, bracket, or brace. 5984.It Xo 5985.Oo Ar n Oc Ns f Ns Ar c 5986.Xc 5987Move forward to the 5988.Ar n Ns th 5989occurrence of the character 5990.Ar c . 5991.It Xo 5992.Oo Ar n Oc Ns F Ns Ar c 5993.Xc 5994Move backward to the 5995.Ar n Ns th 5996occurrence of the character 5997.Ar c . 5998.It Xo 5999.Oo Ar n Oc Ns t Ns Ar c 6000.Xc 6001Move forward to just before the 6002.Ar n Ns th 6003occurrence of the character 6004.Ar c . 6005.It Xo 6006.Oo Ar n Oc Ns T Ns Ar c 6007.Xc 6008Move backward to just before the 6009.Ar n Ns th 6010occurrence of the character 6011.Ar c . 6012.It Xo 6013.Oo Ar n Oc Ns \&; 6014.Xc 6015Repeats the last 6016.Ic f , F , t , 6017or 6018.Ic T 6019command. 6020.It Xo 6021.Oo Ar n Oc Ns \&, 6022.Xc 6023Repeats the last 6024.Ic f , F , t , 6025or 6026.Ic T 6027command, but moves in the opposite direction. 6028.El 6029.Pp 6030Inter-line movement commands: 6031.Bl -tag -width Ds 6032.It Xo 6033.Oo Ar n Oc Ns j , 6034.Oo Ar n Oc Ns + , 6035.No and 6036.Oo Ar n Oc Ns \*(haN 6037.Xc 6038Move to the 6039.Ar n Ns th 6040next line in the history. 6041.It Xo 6042.Oo Ar n Oc Ns k , 6043.Oo Ar n Oc Ns \- , 6044.No and 6045.Oo Ar n Oc Ns \*(haP 6046.Xc 6047Move to the 6048.Ar n Ns th 6049previous line in the history. 6050.It Xo 6051.Oo Ar n Oc Ns G 6052.Xc 6053Move to line 6054.Ar n 6055in the history; if 6056.Ar n 6057is not specified, the number of the first remembered line is used. 6058.It Xo 6059.Oo Ar n Oc Ns g 6060.Xc 6061Like 6062.Ic G , 6063except if 6064.Ar n 6065is not specified, it goes to the most recent remembered line. 6066.It Xo 6067.Oo Ar n Oc Ns / Ns Ar string 6068.Xc 6069Search backward through the history for the 6070.Ar n Ns th 6071line containing 6072.Ar string ; 6073if 6074.Ar string 6075starts with 6076.Ql \*(ha , 6077the remainder of the string must appear at the start of the history line for 6078it to match. 6079.It Xo 6080.Oo Ar n Oc Ns \&? Ns Ar string 6081.Xc 6082Same as 6083.Ic / , 6084except it searches forward through the history. 6085.It Xo 6086.Oo Ar n Oc Ns n 6087.Xc 6088Search for the 6089.Ar n Ns th 6090occurrence of the last search string; 6091the direction of the search is the same as the last search. 6092.It Xo 6093.Oo Ar n Oc Ns N 6094.Xc 6095Search for the 6096.Ar n Ns th 6097occurrence of the last search string; 6098the direction of the search is the opposite of the last search. 6099.It Ar ANSI-CurUp 6100Take the characters from the beginning of the line to the current 6101cursor position as search string and do a backwards history search 6102for lines beginning with this string; keep the cursor position. 6103This works only in insert mode and keeps it enabled. 6104.El 6105.Pp 6106Edit commands 6107.Bl -tag -width Ds 6108.It Xo 6109.Oo Ar n Oc Ns a 6110.Xc 6111Append text 6112.Ar n 6113times; goes into insert mode just after the current position. 6114The append is 6115only replicated if command mode is re-entered i.e.\& 6116.Aq esc 6117is used. 6118.It Xo 6119.Oo Ar n Oc Ns A 6120.Xc 6121Same as 6122.Ic a , 6123except it appends at the end of the line. 6124.It Xo 6125.Oo Ar n Oc Ns i 6126.Xc 6127Insert text 6128.Ar n 6129times; goes into insert mode at the current position. 6130The insertion is only 6131replicated if command mode is re-entered i.e.\& 6132.Aq esc 6133is used. 6134.It Xo 6135.Oo Ar n Oc Ns I 6136.Xc 6137Same as 6138.Ic i , 6139except the insertion is done just before the first non-blank character. 6140.It Xo 6141.Oo Ar n Oc Ns s 6142.Xc 6143Substitute the next 6144.Ar n 6145characters (i.e. delete the characters and go into insert mode). 6146.It S 6147Substitute whole line. 6148All characters from the first non-blank character to the 6149end of the line are deleted and insert mode is entered. 6150.It Xo 6151.Oo Ar n Oc Ns c Ns Ar move-cmd 6152.Xc 6153Change from the current position to the position resulting from 6154.Ar n move-cmd Ns s 6155(i.e. delete the indicated region and go into insert mode); if 6156.Ar move-cmd 6157is 6158.Ic c , 6159the line starting from the first non-blank character is changed. 6160.It C 6161Change from the current position to the end of the line (i.e. delete to the 6162end of the line and go into insert mode). 6163.It Xo 6164.Oo Ar n Oc Ns x 6165.Xc 6166Delete the next 6167.Ar n 6168characters. 6169.It Xo 6170.Oo Ar n Oc Ns X 6171.Xc 6172Delete the previous 6173.Ar n 6174characters. 6175.It D 6176Delete to the end of the line. 6177.It Xo 6178.Oo Ar n Oc Ns d Ns Ar move-cmd 6179.Xc 6180Delete from the current position to the position resulting from 6181.Ar n move-cmd Ns s ; 6182.Ar move-cmd 6183is a movement command (see above) or 6184.Ic d , 6185in which case the current line is deleted. 6186.It Xo 6187.Oo Ar n Oc Ns r Ns Ar c 6188.Xc 6189Replace the next 6190.Ar n 6191characters with the character 6192.Ar c . 6193.It Xo 6194.Oo Ar n Oc Ns R 6195.Xc 6196Replace. 6197Enter insert mode but overwrite existing characters instead of 6198inserting before existing characters. 6199The replacement is repeated 6200.Ar n 6201times. 6202.It Xo 6203.Oo Ar n Oc Ns \*(TI 6204.Xc 6205Change the case of the next 6206.Ar n 6207characters. 6208.It Xo 6209.Oo Ar n Oc Ns y Ns Ar move-cmd 6210.Xc 6211Yank from the current position to the position resulting from 6212.Ar n move-cmd Ns s 6213into the yank buffer; if 6214.Ar move-cmd 6215is 6216.Ic y , 6217the whole line is yanked. 6218.It Y 6219Yank from the current position to the end of the line. 6220.It Xo 6221.Oo Ar n Oc Ns p 6222.Xc 6223Paste the contents of the yank buffer just after the current position, 6224.Ar n 6225times. 6226.It Xo 6227.Oo Ar n Oc Ns P 6228.Xc 6229Same as 6230.Ic p , 6231except the buffer is pasted at the current position. 6232.El 6233.Pp 6234Miscellaneous vi commands 6235.Bl -tag -width Ds 6236.It \*(haJ and \*(haM 6237The current line is read, parsed, and executed by the shell. 6238.It \*(haL and \*(haR 6239Redraw the current line. 6240.It Xo 6241.Oo Ar n Oc Ns \&. 6242.Xc 6243Redo the last edit command 6244.Ar n 6245times. 6246.It u 6247Undo the last edit command. 6248.It U 6249Undo all changes that have been made to the current line. 6250.It Ar intr No and Ar quit 6251The interrupt and quit terminal characters cause the current line to be 6252deleted and a new prompt to be printed. 6253.El 6254.Sh FILES 6255.Bl -tag -width XetcXsuid_profile -compact 6256.It Pa \*(TI/.mkshrc 6257User mkshrc profile (non-privileged interactive shells); see 6258.Sx Startup files. 6259The location can be changed at compile time (for embedded systems); 6260AOSP Android builds use 6261.Pa /system/etc/mkshrc . 6262.It Pa \*(TI/.profile 6263User profile (non-privileged login shells); see 6264.Sx Startup files 6265near the top of this manual. 6266.It Pa /etc/profile 6267System profile (login shells); see 6268.Sx Startup files. 6269.It Pa /etc/shells 6270Shell database. 6271.It Pa /etc/suid_profile 6272Suid profile (privileged shells); see 6273.Sx Startup files. 6274.El 6275.Pp 6276Note: On Android, 6277.Pa /system/etc/ 6278contains the system and suid profile. 6279.Sh SEE ALSO 6280.Xr awk 1 , 6281.Xr cat 1 , 6282.Xr ed 1 , 6283.Xr getopt 1 , 6284.Xr sed 1 , 6285.Xr sh 1 , 6286.Xr stty 1 , 6287.Xr dup 2 , 6288.Xr execve 2 , 6289.Xr getgid 2 , 6290.Xr getuid 2 , 6291.Xr mknod 2 , 6292.Xr mkfifo 2 , 6293.Xr open 2 , 6294.Xr pipe 2 , 6295.Xr rename 2 , 6296.Xr wait 2 , 6297.Xr getopt 3 , 6298.Xr nl_langinfo 3 , 6299.Xr setlocale 3 , 6300.Xr signal 3 , 6301.Xr system 3 , 6302.Xr tty 4 , 6303.Xr shells 5 , 6304.Xr environ 7 , 6305.Xr script 7 , 6306.Xr utf\-8 7 , 6307.Xr mknod 8 6308.Pp 6309.Pa http://docsrv.sco.com:507/en/man/html.C/sh.C.html 6310.Pp 6311.Pa https://www.mirbsd.org/ksh\-chan.htm 6312.Rs 6313.%A Morris Bolsky 6314.%B "The KornShell Command and Programming Language" 6315.%D 1989 6316.%I "Prentice Hall PTR" 6317.%P "xvi\ +\ 356 pages" 6318.%O "ISBN 978\-0\-13\-516972\-8 (0\-13\-516972\-0)" 6319.Re 6320.Rs 6321.%A Morris I. Bolsky 6322.%A David G. Korn 6323.%B "The New KornShell Command and Programming Language (2nd Edition)" 6324.%D 1995 6325.%I "Prentice Hall PTR" 6326.%P "xvi\ +\ 400 pages" 6327.%O "ISBN 978\-0\-13\-182700\-4 (0\-13\-182700\-6)" 6328.Re 6329.Rs 6330.%A Stephen G. Kochan 6331.%A Patrick H. Wood 6332.%B "\\*(tNUNIX\\*(sP Shell Programming" 6333.%V "3rd Edition" 6334.%D 2003 6335.%I "Sams" 6336.%P "xiii\ +\ 437 pages" 6337.%O "ISBN 978\-0\-672\-32490\-1 (0\-672\-32490\-3)" 6338.Re 6339.Rs 6340.%A "IEEE Inc." 6341.%T "\\*(tNIEEE\\*(sP Standard for Information Technology \*(en Portable Operating System Interface (POSIX)" 6342.%V "Part 2: Shell and Utilities" 6343.%D 1993 6344.%I "IEEE Press" 6345.%P "xvii\ +\ 1195 pages" 6346.%O "ISBN 978\-1\-55937\-255\-8 (1\-55937\-255\-9)" 6347.Re 6348.Rs 6349.%A Bill Rosenblatt 6350.%B "Learning the Korn Shell" 6351.%D 1993 6352.%I "O'Reilly" 6353.%P "360 pages" 6354.%O "ISBN 978\-1\-56592\-054\-5 (1\-56592\-054\-6)" 6355.Re 6356.Rs 6357.%A Bill Rosenblatt 6358.%A Arnold Robbins 6359.%B "Learning the Korn Shell, Second Edition" 6360.%D 2002 6361.%I "O'Reilly" 6362.%P "432 pages" 6363.%O "ISBN 978\-0\-596\-00195\-7 (0\-596\-00195\-9)" 6364.Re 6365.Rs 6366.%A Barry Rosenberg 6367.%B "KornShell Programming Tutorial" 6368.%D 1991 6369.%I "Addison-Wesley Professional" 6370.%P "xxi\ +\ 324 pages" 6371.%O "ISBN 978\-0\-201\-56324\-5 (0\-201\-56324\-X)" 6372.Re 6373.Sh AUTHORS 6374.An -nosplit 6375.Nm "The MirBSD Korn Shell" 6376is developed by 6377.An Thorsten Glaser Aq tg@mirbsd.org 6378and currently maintained as part of The MirOS Project. 6379This shell is based on the public domain 7th edition Bourne shell clone by 6380.An Charles Forsyth , 6381who kindly agreed to, in countries where the Public Domain status of the work 6382may not be valid, grant a copyright licence to the general public to deal in 6383the work without restriction and permission to sublicence derivates under the 6384terms of any (OSI approved) Open Source licence, 6385and parts of the BRL shell by 6386.An Doug A. Gwyn , 6387.An Doug Kingston , 6388.An Ron Natalie , 6389.An Arnold Robbins , 6390.An Lou Salkind , 6391and others. 6392The first release of 6393.Nm pdksh 6394was created by 6395.An Eric Gisin , 6396and it was subsequently maintained by 6397.An John R. MacMillan Aq Mt change!john@sq.sq.com , 6398.An Simon J. Gerraty Aq Mt sjg@zen.void.oz.au , 6399and 6400.An Michael Rendell Aq Mt michael@cs.mun.ca . 6401The effort of several projects, such as Debian and OpenBSD, and other 6402contributors including our users, to improve the shell is appreciated. 6403See the documentation, CVS, and web site for details. 6404.Pp 6405The BSD daemon is Copyright \(co Marshall Kirk McKusick. 6406The complete legalese is at: 6407.Pa https://www.mirbsd.org/TaC\-mksh.txt 6408.\" 6409.\" This boils down to: feel free to use mksh.ico as application icon 6410.\" or shortcut for mksh or mksh/Win32; distro patches are ok (but we 6411.\" request they amend $KSH_VERSION when modifying mksh). Authors are 6412.\" Marshall Kirk McKusick (UCB), Rick Collette (ekkoBSD), Thorsten 6413.\" Glaser, Benny Siegert (MirBSD), Michael Langguth (mksh/Win32). 6414.\" 6415.\" As far as MirBSD is concerned, the files themselves are free 6416.\" to modification and distribution under BSD/MirOS Licence, the 6417.\" restriction on use stems only from trademark law's requirement 6418.\" to protect it or lose it, which McKusick almost did. 6419.\" 6420.Sh CAVEATS 6421.Nm 6422only supports the Unicode BMP (Basic Multilingual Plane). 6423.Pp 6424.Nm 6425has a different scope model from 6426.At 6427.Nm ksh , 6428which leads to subtile differences in semantics for identical builtins. 6429This can cause issues with a 6430.Ic nameref 6431to suddenly point to a local variable by accident; fixing this is hard. 6432.Pp 6433The parts of a pipeline, like below, are executed in subshells. 6434Thus, variable assignments inside them are not visible in the 6435surrounding execution environment. 6436Use co-processes instead. 6437.Bd -literal -offset indent 6438foo \*(Ba bar \*(Ba read baz # will not change $baz 6439foo \*(Ba bar \*(Ba& read \-p baz # will, however, do so 6440.Ed 6441.Pp 6442.Nm mksh 6443provides a consistent set of 32-bit integer arithmetics, both signed 6444and unsigned, with defined wraparound and sign of the result of a 6445remainder operation, even (defying POSIX) on 64-bit systems. 6446If you require 64-bit integer arithmetics, use 6447.Nm lksh Pq legacy mksh 6448instead, but be aware that, in POSIX, it's legal for the OS to make 6449.Li print $((2147483647 + 1)) 6450delete all files on your system, as it's Undefined Behaviour. 6451.Sh BUGS 6452Suspending (using \*(haZ) pipelines like the one below will only suspend 6453the currently running part of the pipeline; in this example, 6454.Dq fubar 6455is immediately printed on suspension (but not later after an 6456.Ic fg ) . 6457.Bd -literal -offset indent 6458$ /bin/sleep 666 && echo fubar 6459.Ed 6460.Pp 6461This document attempts to describe 6462.Nm mksh\ R50 6463and up, 6464compiled without any options impacting functionality, such as 6465.Dv MKSH_SMALL , 6466when not called as 6467.Pa /bin/sh 6468which, on some systems only, enables 6469.Ic set \-o sh 6470automatically (whose behaviour differs across targets), 6471for an operating environment supporting all of its advanced needs. 6472Please report bugs in 6473.Nm 6474to the 6475.Mx 6476mailing list at 6477.Aq miros\-mksh@mirbsd.org 6478or in the 6479.Li \&#\&!/bin/mksh 6480.Pq or Li \&#ksh 6481IRC channel at 6482.Pa irc.freenode.net 6483.Pq Port 6697 SSL, 6667 unencrypted , 6484or at: 6485.Pa https://launchpad.net/mksh 6486