1.\" Copyright (c) 1980, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 4. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)swapon.2 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD$ 30.\" 31.Dd October 4, 2013 32.Dt SWAPON 2 33.Os 34.Sh NAME 35.Nm swapon , swapoff 36.Nd control devices for interleaved paging/swapping 37.Sh LIBRARY 38.Lb libc 39.Sh SYNOPSIS 40.In unistd.h 41.Ft int 42.Fn swapon "const char *special" 43.Ft int 44.Fn swapoff "const char *special" 45.Sh DESCRIPTION 46The 47.Fn swapon 48system call 49makes the block device 50.Fa special 51available to the system for 52allocation for paging and swapping. 53The names of potentially 54available devices are known to the system and defined at system 55configuration time. 56The size of the swap area on 57.Fa special 58is calculated at the time the device is first made available 59for swapping. 60.Pp 61The 62.Fn swapoff 63system call disables paging and swapping on the given device. 64All associated swap metadata are deallocated, and the device 65is made available for other purposes. 66.Sh RETURN VALUES 67If an error has occurred, a value of -1 is returned and 68.Va errno 69is set to indicate the error. 70.Sh ERRORS 71Both 72.Fn swapon 73and 74.Fn swapoff 75can fail if: 76.Bl -tag -width Er 77.It Bq Er ENOTDIR 78A component of the path prefix is not a directory. 79.It Bq Er ENAMETOOLONG 80A component of a pathname exceeded 255 characters, 81or an entire path name exceeded 1023 characters. 82.It Bq Er ENOENT 83The named device does not exist. 84.It Bq Er EACCES 85Search permission is denied for a component of the path prefix. 86.It Bq Er ELOOP 87Too many symbolic links were encountered in translating the pathname. 88.It Bq Er EPERM 89The caller is not the super-user. 90.It Bq Er EFAULT 91The 92.Fa special 93argument 94points outside the process's allocated address space. 95.El 96.Pp 97Additionally, 98.Fn swapon 99can fail for the following reasons: 100.Bl -tag -width Er 101.It Bq Er ENOTBLK 102The 103.Fa special 104argument 105is not a block device. 106.It Bq Er EBUSY 107The device specified by 108.Fa special 109has already 110been made available for swapping 111.It Bq Er ENXIO 112The major device number of 113.Fa special 114is out of range (this indicates no device driver exists 115for the associated hardware). 116.It Bq Er EIO 117An I/O error occurred while opening the swap device. 118.El 119.Pp 120Lastly, 121.Fn swapoff 122can fail if: 123.Bl -tag -width Er 124.It Bq Er EINVAL 125The system is not currently swapping to 126.Fa special . 127.It Bq Er ENOMEM 128Not enough virtual memory is available to safely disable 129paging and swapping to the given device. 130.El 131.Sh SEE ALSO 132.Xr config 8 , 133.Xr swapon 8 , 134.Xr sysctl 8 135.Sh HISTORY 136The 137.Fn swapon 138system call appeared in 139.Bx 4.0 . 140The 141.Fn swapoff 142system call appeared in 143.Fx 5.0 . 144