losetup — set up and control loop devices


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


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).


+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)

−D, −−detach−all

detach all associated loop devices

−f, −−find

find the first unused loop device. If a file argument is present, use this device. Otherwise, print its name

−h, −−help

print help

−j, −−associated file

show status of all loop devices associated with given file

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. See also −−output, −−noheadings and −−raw.

−n, −−noheadings

don't print headings for −−list output format

−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


use raw −−list output format

−r, −−read−only

setup read-only loop device


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

−v, −−verbose

verbose mode


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


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 status of the device.



loop block devices


loop control device


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
# mkfs -t ext2 /dev/loop0
# mount /dev/loop0 /mnt
# umount /dev/loop0
# losetup --detach /dev/loop0


Karel Zak <>, based on original version from Theodore Ts'o <>


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