swapon

SWAPON(8)                  Linux Programmer's Manual                 SWAPON(8)



NAME
       swapon, swapoff - enable/disable devices and files for paging and swap‐
       ping

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  avail‐
       able from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.



Linux 1.x                      25 September 1995                     SWAPON(8)