swapon
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Name

swapon, swapoff — enable/disable devices and files for paging and swapping

Synopsis

/sbin/swapon [ −h −V ]

/sbin/swapon −a [−v] [−e]

/sbin/swapon [−v] [ −p priority ] specialfile...

/sbin/swapon [−s]

/sbin/swapoff [ −h −V ]

/sbin/swapoff −a

/sbin/swapoff specialfile...

DESCRIPTION

Swapon is used to specify devices on which paging and swapping are to take place.

The device or file used is given by the specialfile parameter. It may be of the form −L label or −U uuid to indicate a device by label or uuid.

Calls to swapon normally occur in the system multi-user initialization file /etc/rc making all swap devices available, so that the paging and swapping activity is interleaved across several devices and files.

Normally, the first form is used:

−a

All devices marked as ``swap'' swap devices in /etc/fstab are made available, except for those with the ``noauto'' option. Devices that are already running as swap are silently skipped.

−e

When −a is used with swapon, −e makes swapon silently skip devices that do not exist.

−h

Provide help

−L label

Use the partition that has the specified label. (For this, access to /proc/partitions is needed.)

−p priority

Specify priority for swapon. This option is only available if swapon was compiled under and is used under a 1.3.2 or later kernel. priority is a value between 0 and 32767. Higher numbers indicate higher priority. See swapon(2) for a full description of swap priorities. Add pri=value to the option field of /etc/fstab for use with swapon -a.

−s

Display swap usage summary by device. Equivalent to "cat /proc/swaps". Not available before Linux 2.1.25.

−U uuid

Use the partition that has the specified uuid. (For this, access to /proc/partitions is needed.)

−v

Be verbose.

−V

Display version

Swapoff disables swapping on the specified devices and files. When the −a flag is given, swapping is disabled on all known swap devices and files (as found in /proc/swaps or /etc/fstab).

NOTE

You should not use swapon on a file with holes. Swap over NFS may not work.

SEE ALSO

swapon(2), swapoff(2), fstab(5), init(8), mkswap(8), rc(8), mount(8)

FILES

/dev/hd?? standard paging devices

/dev/sd?? standard (SCSI) paging devices

/etc/fstab ascii filesystem description table

HISTORY

The swapon command appeared in 4.0BSD.


  Copyright (c) 1980, 1991 Regents of the University of California.
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
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   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. All advertising materials mentioning features or use of this software
   must display the following acknowledgement:
This product includes software developed by the University of
California, Berkeley and its contributors.
4. Neither the name of the University nor the names of its contributors
   may be used to endorse or promote products derived from this software
   without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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
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SUCH DAMAGE.

    (#)swapon.8 6.3 (Berkeley) 3/16/91

Sun Dec 27 12:31:30 1992: Modified by faithcs.unc.edu
Sat Mar  6 20:46:02 1993: Modified by faithcs.unc.edu
Sat Oct  9 09:35:30 1993: Converted to man format by faithcs.unc.edu
Sat Nov 27 20:22:42 1993: Updated authorship information, faithcs.unc.edu
Mon Sep 25 14:12:38 1995: Added -v and -p information
Tue Apr 30 03:32:07 1996: Added some text from A. Koppenhoefer
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