.\" $OpenBSD: swapctl.8,v 1.26 2006/08/24 08:51:55 jmc Exp $ .\" $NetBSD: swapctl.8,v 1.14 1998/05/22 18:27:52 msaitoh Exp $ .\" .\" Copyright (c) 1997 Matthew R. Green .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. The name of the author may not be used to endorse or promote products .\" derived from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, .\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED .\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, .\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .Dd June 12, 1997 .Dt SWAPCTL 8 .Os .Sh NAME .Nm swapctl , .Nm swapon .Nd system swap management tool .Sh SYNOPSIS .Nm swapctl .Fl A .Op Fl p Ar priority .Op Fl t Ar blk|noblk .Nm swapctl .Fl a .Op Fl p Ar priority .Ar path .Nm swapctl .Fl c .Fl p Ar priority .Ar path .Nm swapctl .Fl d .Ar path .Nm swapctl .Fl l | Fl s .Op Fl k .Nm swapon .Fl a | Ar path .Sh DESCRIPTION The .Nm program adds, removes, lists and prioritizes swap devices and files for the system. The .Nm swapon program acts the same as .Ic swapctl -a , except if .Nm swapon itself is called with .Fl a , in which case it acts as .Ic swapctl -A . .Pp .Sy Note : The initial swap device (root disk, partition b) is handled automatically by the kernel and does .Em not need to be added to .Pa /etc/fstab or added via .Nm swapctl . It will show up as .Qq swap_device in the output displayed with the .Fl l flag. .Pp The options are as follows: .Bl -tag -width Ds .It Fl A This option causes .Nm to read the .Pa /etc/fstab file for devices and files with an .Dq sw type, and adds all these entries as swap devices. If no swap devices are configured, .Nm will exit with an error code. .It Fl a The .Fl a option requires that a .Ar path also be in the argument list. The .Ar path is added to the kernel's list of swap devices using the .Xr swapctl 2 system call. When using the .Nm swapon form of this command, the .Fl a option is treated the same as the .Fl A option, for backwards compatibility. .It Fl c The .Fl c option changes the priority of the listed swap device or file. .It Fl d Ar path The .Fl d option removes the listed .Ar path from the kernel's list of swap devices or files. .It Fl k The .Fl k option uses 1024 byte blocks instead of the default 512 byte. .It Fl l The .Fl l option lists the current swap devices and files, and their usage statistics. .It Fl p Ar priority The .Fl p option sets the priority of swap devices or files to the .Ar priority argument. This works with the .\" .Fl d , .Fl a , .Fl c and .Fl l options. .It Fl s The .Fl s option displays a single line summary of current swap statistics. .It Fl t Ar blk|noblk This flag modifies the function of the .Fl A option. The .Fl t option allows the type of device to add to be specified. An argument of .Ar blk causes all block devices in .Pa /etc/fstab to be added. An argument of .Ar noblk causes all non-block devices in .Pa /etc/fstab to be added. This option is useful in early system startup, where swapping may be needed before all file systems are available, such as during disk checks of large file systems. .El .Pp .Ex -std swapctl .Sh SWAP OPTIONS When parsing the .Pa /etc/fstab file for swap devices, lines such as the following specify additional swap devices: .Bd -literal -offset indent /dev/sd1b none swap sw 0 0 .Ed .Pp Additional flags include: .Pp .Bl -tag -width nfsmntpt=/path -compact .It priority=N Swap devices and files may be assigned different priorities, to allow faster resources to be used first. Swap devices at the same priority are used in a round-robin fashion until there is no more space available at this priority, when the next priority level will be used. The default priority is 0, the highest. This value can be any valid integer, with higher values receiving less priority. .It nfsmntpt=/path This option is useful for swapping to NFS files. It specifies the local mount point to mount an NFS filesystem. Typically, once this mount has succeeded, the file to be used for swapping on will be available under this point mount. For example: .Bd -literal server:/export/swap/client none swap sw,nfsmntpt=/swap .Ed .El .Sh SEE ALSO .Xr swapctl 2 , .Xr fstab 5 , .Xr mount_nfs 8 , .Xr vnconfig 8 .Sh HISTORY The .Nm program was originally developed in .Nx 1.3 . It was ported to .Ox 2.6 by Tobias Weingartner. The original .Nm swapon program, provided for backwards compatibility, appeared in .Bx 4.0 . .Sh AUTHORS The .Nm program was written by .An Matthew R. Green Aq mrg@eterna.com.au . .Sh BUGS Local and remote swap files cannot be configured until the file systems they reside on are mounted read/write. The system startup scripts need to .Xr fsck 8 all local file systems before this can happen. This process requires substantial amounts of memory on some systems. If one configures no local block swap devices on a machine that has local file systems to check and rely only on swap files, the machine will have no swap space at all during system .Xr fsck 8 and may run out of real memory, causing fsck to abnormally exit and startup scripts to fail.