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LOSETUP(8)                                      System Administration                                      LOSETUP(8)



NAME
       losetup - set up and control loop devices

SYNOPSIS
       Get info:

            losetup loopdev

            losetup -l [-a]

            losetup -j file [-o offset]

       Delete loop:

            losetup -d loopdev...

       Delete all used loop devices:

            losetup -D

       Print name of first unused loop device:

            losetup -f

       Setup loop device:

            losetup [-o offset] [--sizelimit size]
                    [-p pfd] [-rP] {-f[--show]|loopdev} file

       Resize loop device:

            losetup -c loopdev

DESCRIPTION
       losetup  is  used to associate loop devices with regular files or block devices, to detach loop devices and to
       query the status of a loop device. If only the loopdev argument is given, the status of the corresponding loop
       device is shown.

       Note  that the old output format (e.g. losetup -a) with comma delimited strings is deprecated in favour of the
       --list output format (e.g. losetup -a -l).

OPTIONS
       +The size and offset arguments may be followed by the multiplicative +suffixes KiB=1024, MiB=1024*1024, and so
       on  for GiB, TiB, PiB, EiB, ZiB and YiB +(the "iB" is optional, e.g. "K" has the same meaning as "KiB") or the
       suffixes +KB=1000, MB=1000*1000, and so on for GB, TB, PB, EB, ZB and YB.


       -a, --all
              show status of all loop devices. Note that not all information are accessible for non-root  users.  See
              also --list. The old output format (as printed without --list) is deprecated.

       -c, --set-capacity loopdev
              force loop driver to reread size of the file associated with the specified loop device

       -d, --detach loopdev...
              detach the file or device associated with the specified loop device(s)
              show status of all loop devices associated with given file

       -l, --list
              if a loop device or the -a option is specified, print default columns for  either  the  specified  loop
              device or all loop devices, default is to print info about all devices.

       -o, --offset offset
              the data start is moved offset bytes into the specified file or device

       -O, --output columns
              specify which columns are to be printed for the --list output

       --sizelimit size
              the data end is set to no more than size bytes after the data start

       -P, --partscan
              force kernel to scan partition table on newly created loop device

       -r, --read-only
              setup read-only loop device

       --show print device name if the -f option and a file argument are present.

       -v, --verbose
              verbose mode


ENCRYPTION
       Cryptoloop is no longer supported in favor of dm-crypt. For more details see cryptsetup(8).


RETURN VALUE
       losetup  returns  0  on  success,  nonzero  on  failure. When losetup displays the status of a loop device, it
       returns 1 if the device is not configured and 2 if an error occurred which prevented from determining the sta‐
       tus of the device.


FILES
       /dev/loop[0..N]
              loop block devices

       /dev/loop-cotrol
              loop control device


EXAMPLE
       The following commands can be used as an example of using the loop device.

              # dd if=/dev/zero of=~/file.img bs=1MiB count=10
              # losetup --find --show ~/file.img
              /dev/loop0
              # mkfs -t ext2 /dev/loop0
              # mount /dev/loop0 /mnt
               ...

util-linux                                            July 2003                                            LOSETUP(8)