centos man page for losetup

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)

       -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

       -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 con-
       figured and 2 if an error occurred which prevented from determining the status 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
	       ...
	      # umount /dev/loop0
	      # losetup --detach /dev/loop0

AUTHORS
       Karel Zak <kzak@redhat.com>, based on original version from Theodore Ts'o <tytso@athena.mit.edu>

AVAILABILITY
       The losetup command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.

util-linux							     July 2003								LOSETUP(8)