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.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)swapon.2 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD: src/lib/libc/sys/swapon.2,v 1.6.2.6 2001/12/14 18:34:01 ru Exp $ 34.\" $DragonFly: src/lib/libc/sys/swapon.2,v 1.3 2006/02/17 19:35:06 swildner Exp $ 35.\" 36.Dd September 7, 2010 37.Dt SWAPON 2 38.Os 39.Sh NAME 40.Nm swapon , swapoff 41.Nd control devices for interleaved paging/swapping 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In unistd.h 46.Ft int 47.Fn swapon "const char *special" 48.Ft int 49.Fn swapoff "const char *special" 50.Sh DESCRIPTION 51The 52.Fn swapon 53system call 54makes the block device 55.Fa special 56available to the system for 57allocation for paging and swapping. 58The names of potentially 59available devices are known to the system and defined at system 60configuration time. 61The size of the swap area on 62.Fa special 63is calculated at the time the device is first made available 64for swapping. 65.Pp 66The 67.Fn swapoff 68system call disables paging and swapping on the given device. 69All associated swap metadata are deallocated, and the device 70is made available for other purposes. 71.Sh RETURN VALUES 72If an error has occurred, a value of -1 is returned and 73.Va errno 74is set to indicate the error. 75.Sh ERRORS 76Both 77.Fn swapon 78and 79.Fn swapoff 80can fail if: 81.Bl -tag -width Er 82.It Bq Er ENOTDIR 83A component of the path prefix is not a directory. 84.It Bq Er ENAMETOOLONG 85A component of a pathname exceeded 255 characters, 86or an entire path name exceeded 1023 characters. 87.It Bq Er ENOENT 88The named device does not exist. 89.It Bq Er EACCES 90Search permission is denied for a component of the path prefix. 91.It Bq Er ELOOP 92Too many symbolic links were encountered in translating the pathname. 93.It Bq Er EPERM 94The caller is not the super-user. 95.It Bq Er EFAULT 96The 97.Fa special 98argument 99points outside the process's allocated address space. 100.El 101.Pp 102Additionally, 103.Fn swapon 104can fail for the following reasons: 105.Bl -tag -width Er 106.It Bq Er EINVAL 107The system has reached the boot-time limit on the number of 108swap devices, 109.Va vm.nswapdev . 110.It Bq Er ENOTBLK 111The 112.Fa special 113argument 114is not a block device. 115.It Bq Er EBUSY 116The device specified by 117.Fa special 118has already 119been made available for swapping 120.It Bq Er ENXIO 121The major device number of 122.Fa special 123is out of range (this indicates no device driver exists 124for the associated hardware). 125.It Bq Er EIO 126An I/O error occurred while opening the swap device. 127.El 128.Pp 129Lastly, 130.Fn swapoff 131can fail if: 132.Bl -tag -width Er 133.It Bq Er EINVAL 134The system is not currently swapping to 135.Fa special . 136.It Bq Er ENOMEM 137Not enough virtual memory is available to safely disable 138paging and swapping to the given device. 139.El 140.Sh SEE ALSO 141.Xr config 8 , 142.Xr swapon 8 , 143.Xr sysctl 8 144.Sh HISTORY 145The 146.Fn swapon 147system call appeared in 148.Bx 4.0 . 149The 150.Fn swapoff 151system call appeared in 152.Fx 5.0 153and was later ported to 154.Dx 2.7 . 155