Yolinux.com

losetup manpage

Search topic Section


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 corre-
       sponding 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. los-
       etup -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 out-
	      put 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 config-
       ured 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)