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SWAPON


Section: Linux Programmer’s Manual (8)
Updated: 25 September 1995
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NAME

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

SYNOPSIS

Get info:

swapon -s

[-h]

[-V]

Enable/disable:

swapon

[-f]

[-p

priority]

[-v]

specialfile


swapoff

[-v]

specialfile

Enable/disable all:

swapon -a

[-e]

[-f]

[-v]


swapoff -a

[-v]

 

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 boot scripts making all swap devices available, so
that the paging and swapping activity is interleaved across several devices and
files.


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).



-a, –all


All devices marked as “swap” in
/etc/fstab

are made available, except for those with the “noauto” option.
Devices that are already being used as swap are silently skipped.

-e, –ifexists


Silently skip devices that do not exist.
-f, –fixpgsz


Reinitialize (exec /sbin/mkswap) the swap space if its page size does not
match that of the the current running kernel.
mkswap(2)

initializes the whole device and does not check for bad blocks.

-h, –help


Provide help.
-L label


Use the partition that has the specified
label.

(For this, access to
/proc/partitions

is needed.)

-p, –priority priority


Specify the priority of the swap device.
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, –summary


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.

-v, –verbose


Be verbose.
-V, –version


Display version.

 

NOTES

You should not use
swapon

on a file with holes.
Swap over NFS may not work.

swapon

automatically detects and rewrites swap space signature with old software
suspend data (e.g S1SUSPEND, S2SUSPEND, …). The problem is that if we don’t
do it, then we get data corruption the next time an attempt at unsuspending is
made.
 

SEE ALSO

swapon(2),

swapoff(2),

fstab(5),

init(8),

mkswap(8),

rc(8),

mount(8)

 

FILES


/dev/sd??

standard paging devices

/etc/fstab

ascii filesystem description table
 

HISTORY

The
swapon

command appeared in 4.0BSD.
 

AVAILABILITY

The swapon command is part of the util-linux-ng package and is available from
ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.



 

Index



NAME

SYNOPSIS

DESCRIPTION

NOTES

SEE ALSO

FILES

HISTORY

AVAILABILITY



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