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       swapon,  swapoff  -  enable/disable  devices  and  files for paging and


       Get info:
            swapon -s [-h] [-V]

            swapon [-f] [-p priority] [-v] specialfile...
            swapoff [-v] specialfile...

       Enable/disable all:
            swapon -a [-e] [-f] [-v]
            swapoff -a [-v]


       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

       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).

       If  loop=/dev/loop?   and  encryption=AES128  options  are  present  in
       /etc/fstab then swapon -a will set up loop devices using  random  keys,
       run  mkswap  on  them,  and  enable  encrypted  swap  on specified loop
       devices. Encrypted loop devices are set up with  page  size  offset  so
       that  unencrypted swap signatures on first page of swap devices are not
       touched.  swapoff -a will tear down such loop devices.

       -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

       -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.


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

       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.


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


       /dev/sd??  standard paging devices
       /etc/fstab ascii filesystem description table


       The swapon command appeared in 4.0BSD.


       The  swapon  command  is  part  of  the  util-linux-ng  package  and is
       available from