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 priprity
-
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/.