1.\"	$OpenBSD: getpgrp.2,v 1.12 2003/06/02 20:18:39 millert Exp $
2.\"	$NetBSD: getpgrp.2,v 1.8 1995/02/27 12:33:09 cgd Exp $
3.\"
4.\" Copyright (c) 1983, 1991, 1993
5.\"	The Regents of the University of California.  All rights reserved.
6.\"
7.\" Redistribution and use in source and binary forms, with or without
8.\" modification, are permitted provided that the following conditions
9.\" are met:
10.\" 1. Redistributions of source code must retain the above copyright
11.\"    notice, this list of conditions and the following disclaimer.
12.\" 2. Redistributions in binary form must reproduce the above copyright
13.\"    notice, this list of conditions and the following disclaimer in the
14.\"    documentation and/or other materials provided with the distribution.
15.\" 3. Neither the name of the University nor the names of its contributors
16.\"    may be used to endorse or promote products derived from this software
17.\"    without specific prior written permission.
18.\"
19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29.\" SUCH DAMAGE.
30.\"
31.\"     @(#)getpgrp.2	8.1 (Berkeley) 6/4/93
32.\"
33.Dd June 4, 1993
34.Dt GETPGRP 2
35.Os
36.Sh NAME
37.Nm getpgrp
38.Nd get process group
39.Sh SYNOPSIS
40.Fd #include <unistd.h>
41.Ft pid_t
42.Fn getpgrp "void"
43.Ft pid_t
44.Fn getpgid "pid_t pid"
45.Sh DESCRIPTION
46The process group of the current process is returned by
47.Fn getpgrp .
48The process group of the
49.Fa pid
50process is returned by
51.Fn getpgid .
52.Pp
53Process groups are used for distribution of signals, and
54by terminals to arbitrate requests for their input: processes
55that have the same process group as the terminal are foreground
56and may read, while others will block with a signal if they attempt
57to read.
58.Pp
59This call is thus used by programs such as
60.Xr csh 1
61to create
62process groups
63in implementing job control.
64The
65.Fn tcgetpgrp
66and
67.Fn tcsetpgrp
68calls
69are used to get/set the process group of the control terminal.
70.Sh ERRORS
71.Fn getpgrp
72always succeeds, however
73.Fn getpgid
74will succeed unless:
75.Bl -tag -width Er
76.It Bq Er EPERM
77The current process and the process
78.Fa pid
79are not in the same session.
80.It Bq Er ESRCH
81There is no process with a process ID equal to
82.Fa pid .
83.El
84.Sh SEE ALSO
85.Xr setpgid 2 ,
86.Xr termios 4
87.Sh STANDARDS
88This version of
89.Fn getpgrp
90differs from past Berkeley versions by not taking a
91.Fa "pid_t pid"
92argument.
93This incompatibility is required by
94.St -p1003.1-88 .
95.Pp
96From the
97.St -p1003.1-88
98Rationale:
99.Pp
100.Bx 4.3
101provides a
102.Fn getpgrp
103function that returns the process group ID for a specified process.
104Although this function is used to support job control, all known
105job-control shells always specify the calling process with this
106function.
107Thus, the simpler System V
108.Fn getpgrp
109suffices, and the added complexity of the
110.Bx 4.3
111.Fn getpgrp
112has been omitted from POSIX.1.
113.Pp
114The
115.Fn getpgrp
116function conforms to
117.St -p1003.1-88 .
118The
119.Fn getpgid
120function call is derived from its usage in System V Release 4, and
121first appeared in
122.Nx 1.2a .
123.Sh HISTORY
124The
125.Fn getpgrp
126function call appeared in
127.Bx 4.0 .
128