losetup

set up and control loop devices

Usage

Get info:

losetup [loopdev]
losetup -l [-a]
losetup -j file

Attach a loop device:

losetup -fP file

Detach a loop device:

losetup -d loopdev ...

Detach all associated loop devices:

losetup -D

Options

Option	Description
-a, --all	Show the status of all loop devices
-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 [file]	Find the first unused loop device. If a file argument is present, use the found device as loop device. Otherwise, just print its name
--show	Display the name of the assigned loop device if the -f option and a file argument are present
-L, --nooverlap	Check for conflicts between loop devices to avoid situation when the same backing file is shared between more loop devices. If the file is already used by another device then re-use the device rather than a new one. The option makes sense only with --find
-j, --associated file	Show the status of all loop devices associated with the given file
-P, --partscan	Force the kernel to scan the partition table on a newly created loop device. Note that the partition table parsing depends on sector sizes
-r, --read-only	Set up a read-only loop device
-v, --verbose	Verbose mode
-l, --list	If a loop device or the -a option is specified, print the default columns for either the specified loop device or all loop devices
-O, --output column[,column]...	Specify the columns that are to be printed for the --list output
-J, --json	Use JSON format for --list output

Output Columns

Output	Description
NAME	loop device name
AUTOCLEAR	autoclear flag set
BACK-FILE	device backing file
BACK-INO	backing file inode number
BACK-MAJ:MIN	backing file major:minor device number
MAJ:MIN	loop device major:minor number
OFFSET	offset from the beginning
PARTSCAN	partscan flag set
RO	read-only device
SIZELIMIT	size limit of the file in bytes
DIO	access backing file with direct-io
LOG-SEC	logical sector size in bytes