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



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 swap-
       ping 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/.



Linux 1.x                                               25 September 1995                                              SWAPON(8)