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.8 8.1 (Berkeley) 6/5/93 33.\" $FreeBSD$ 34.\" 35.Dd June 5, 1993 36.Dt SWAPON 8 37.Os 38.Sh NAME 39.Nm swapon , swapoff 40.Nd "specify devices for paging and swapping" 41.Sh SYNOPSIS 42.Nm swap[on|off] 43.Fl a 44.Nm swap[on|off] 45.Ar special_file ... 46.Nm swapctl 47.Fl lshk 48.Nm swapctl 49.Fl AU 50.Nm swapctl 51.Fl a 52.Ar special_file ... 53.Nm swapctl 54.Fl d 55.Ar special_file ... 56.Sh DESCRIPTION 57The 58.Nm swap[on,off,ctl] 59utilties are used to control swap devices in the system. At boot time all 60swap entries in 61.Pa /etc/fstab 62are added automatically when the system goes multi-user. 63Swap devices are interleaved and kernels are typically configured 64to handle a maximum of 4 swap devices. There is no priority mechanism. 65.Pp 66The 67.Nm swapon 68utility adds the specified swap devices to the system. If the 69.Fl a 70option is used, all swap devices in 71.Pa /etc/fstab 72will be added, unless their ``noauto'' option is also set. 73.Pp 74The 75.Nm swapoff 76utility removes the specified swap devices from the system. If the 77.Fl a 78option is used, all swap devices in 79.Pa /etc/fstab 80will be removed, unless their ``noauto'' option is also set. 81Note that 82.Nm swapoff 83will fail and refuse to remove a swap device if there is insufficient 84VM (memory + remaining swap devices) to run the system. 85.Nm Swapoff 86must move swapped pages out of the device being removed which could 87lead to high system loads for a period of time, depending on how 88much data has been swapped out to that device. 89.Pp 90The 91.Nm swapctl 92utility exists primarily for those familiar with other BSDs and may be 93used to add, remove, or list swap. Note that the 94.Fl a 95option is used diferently in 96.Nm swapctl 97and indicates that a specific list of devices should be added. 98The 99.Fl d 100option indicates that a specific list should be removed. The 101.Fl A 102and 103.Fl D 104options to 105.Nm swapctl 106operate on all swap entries in 107.Pa /etc/fstab 108which do not have their ``noauto'' option set. 109.Pp 110Swap information can be generated using the 111.Nm swapinfo 112program, 113.Nm pstat 114.Fl s , 115or 116.Nm swapctl 117.Fl lshk . 118The 119.Nm swapctl 120utility has the following options for listing swap: 121.Bl -tag -width indent 122.It Fl l 123List the devices making up system swap. 124.It Fl s 125Print a summary line for system swap. 126.It Fl h 127Output values in megabytes. 128.It Fl k 129Output values in kilobytes. 130.Pp 131The BLOCKSIZE environment variable is used if not specifically 132overridden. 512 byte blocks are used by default. 133.El 134.Sh SEE ALSO 135.Xr swapon 2 , 136.Xr fstab 5 , 137.Xr init 8 , 138.Xr mdconfig 8 , 139.Xr pstat 8 , 140.Xr rc 8 141.Sh FILES 142.Bl -tag -width "/dev/{ad,da}?s?b" -compact 143.It Pa /dev/{ad,da}?s?b 144standard paging devices 145.It Pa /dev/md? 146memory disk devices 147.It Pa /etc/fstab 148ASCII file system description table 149.El 150.Sh HISTORY 151The 152.Nm swapon 153utility appeared in 154.Bx 4.0 . 155The 156.Nm swapoff 157utility appeared in 158.Fx 5.0 . 159