knowledge/technology/applications/cli/system/losetup.md
2024-01-17 09:00:45 +01:00

5.6 KiB

obj repo
application git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git

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