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.8 8.1 (Berkeley) 6/5/93 29.\" $FreeBSD$ 30.\" 31.Dd November 22, 2013 32.Dt SWAPON 8 33.Os 34.Sh NAME 35.Nm swapon , swapoff , swapctl 36.Nd "specify devices for paging and swapping" 37.Sh SYNOPSIS 38.Nm swapon 39.Oo Fl F Ar fstab 40.Oc 41.Fl aLq | Ar 42.Nm swapoff 43.Oo Fl F Ar fstab 44.Oc 45.Fl aLq | Ar 46.Nm swapctl 47.Op Fl AghklmsU 48.Oo 49.Fl a Ar 50| 51.Fl d Ar 52.Oc 53.Sh DESCRIPTION 54The 55.Nm swapon , swapoff 56and 57.Nm swapctl 58utilities are used to control swap devices in the system. 59At boot time all swap entries in 60.Pa /etc/fstab 61are added automatically when the system goes multi-user. 62Swap devices use a fixed interleave; the maximum number of devices 63is unlimited. 64There is no priority mechanism. 65.Pp 66The 67.Nm swapon 68utility adds the specified swap devices to the system. 69If the 70.Fl a 71option is used, all swap devices in 72.Pa /etc/fstab 73will be added, unless their 74.Dq noauto 75or 76.Dq late 77option is also set. 78If the 79.Fl L 80option is specified, 81swap devices with the 82.Dq late 83option will be added as well as ones with no option. 84If the 85.Fl q 86option is used, 87informational messages will not be 88written to standard output when a swap device is added. 89.Pp 90The 91.Nm swapoff 92utility removes the specified swap devices from the system. 93If the 94.Fl a 95option is used, all swap devices in 96.Pa /etc/fstab 97will be removed, unless their 98.Dq noauto 99or 100.Dq late 101option is also set. 102If the 103.Fl L 104option is specified, 105swap devices with the 106.Dq late 107option will be removed as well as ones with no option. 108If the 109.Fl q 110option is used, 111informational messages will not be 112written to standard output when a swap device is removed. 113Note that 114.Nm swapoff 115will fail and refuse to remove a swap device if there is insufficient 116VM (memory + remaining swap devices) to run the system. 117The 118.Nm swapoff 119utility 120must move swapped pages out of the device being removed which could 121lead to high system loads for a period of time, depending on how 122much data has been swapped out to that device. 123.Pp 124Other options supported by both 125.Nm swapon 126and 127.Nm swapoff 128are as follows: 129.Bl -tag -width indent 130.It Fl F Ar fstab 131Specify the 132.Pa fstab 133file to use. 134.El 135.Pp 136The 137.Nm swapctl 138utility exists primarily for those familiar with other 139.Bx Ns s 140and may be 141used to add, remove, or list swap devices. 142Note that the 143.Fl a 144option is used differently in 145.Nm swapctl 146and indicates that a specific list of devices should be added. 147The 148.Fl d 149option indicates that a specific list should be removed. 150The 151.Fl A 152and 153.Fl U 154options to 155.Nm swapctl 156operate on all swap entries in 157.Pa /etc/fstab 158which do not have their 159.Dq noauto 160option set. 161.Pp 162Swap information can be generated using the 163.Xr swapinfo 8 164utility, 165.Nm pstat 166.Fl s , 167or 168.Nm swapctl 169.Fl l . 170The 171.Nm swapctl 172utility has the following options for listing swap: 173.Bl -tag -width indent 174.It Fl h 175Output values in human-readable form. 176.It Fl g 177Output values in gigabytes. 178.It Fl k 179Output values in kilobytes. 180.It Fl m 181Output values in megabytes. 182.It Fl l 183List the devices making up system swap. 184.It Fl s 185Print a summary line for system swap. 186.Pp 187The 188.Ev BLOCKSIZE 189environment variable is used if not specifically 190overridden. 191512 byte blocks are used by default. 192.El 193.Sh FILES 194.Bl -tag -width ".Pa /dev/{ada,da}?s?b" -compact 195.It Pa /dev/{ada,da}?s?b 196standard paging devices 197.It Pa /dev/md? 198memory disk devices 199.It Pa /etc/fstab 200.Tn ASCII 201file system description table 202.El 203.Sh DIAGNOSTICS 204These utilities may fail for the reasons described in 205.Xr swapon 2 . 206.Sh SEE ALSO 207.Xr swapon 2 , 208.Xr fstab 5 , 209.Xr init 8 , 210.Xr mdconfig 8 , 211.Xr pstat 8 , 212.Xr rc 8 213.Sh HISTORY 214The 215.Nm swapon 216utility appeared in 217.Bx 4.0 . 218The 219.Nm swapoff 220and 221.Nm swapctl 222utilities appeared in 223.Fx 5.1 . 224