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.
Show the status of all loop devices. Note that not all
information is accessible for non-root users. See also --list. The old
output format (as printed without --list) is deprecated.
-d, --detach loopdev...
Detach the file or device associated with the specified
loop device(s). Note that since Linux v3.7 kernel uses "lazy device
destruction". The detach operation does not return EBUSY error
anymore if device is actively used by system, but it is marked by autoclear
flag and destroyed later.
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.
Display the name of the assigned loop device if the
-f option and a file argument are present.
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 [-o
Show the status of all loop devices associated with the
-o, --offset offset
The data start is moved offset bytes into the
specified file or device. The offset may be followed by the
multiplicative suffixes; see above.
The data end is set to no more than size bytes
after the data start. The size may be followed by the multiplicative
suffixes; see above.
-b, --sector-size size
Set the logical sector size of the loop device in bytes
(since Linux 4.14). The option may be used when create a new loop device as
well as stand-alone command to modify sector size of the already existing loop
-c, --set-capacity loopdev
Force the loop driver to reread the size of the file
associated with the specified loop device.
Force the kernel to scan the partition table on a newly
created loop device. Note that the partition table parsing depends on sector
sizes. The default is sector size is 512 bytes, otherwise you need to use the
option --sector-size together with --partscan.
Set up a read-only loop device.
Enable or disable direct I/O for the backing file. The
optional argument can be either on or off. If the argument is
omitted, it defaults to off.
If a loop device or the -a option is specified,
print the default columns for either the specified loop device or all loop
devices; the default is to print info about all devices. See also
--output, --noheadings, --raw, and --json.
-O, --output column[,column]...
Specify the columns that are to be printed for the
--list output. Use --help to get a list of all supported
Output all available columns.
Don’t print headings for --list output
Use the raw --list output format.
Use JSON format for --list output.
Display version information and exit.
Display help text and exit.