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losetup(8) [centos man page]

LOSETUP(8)						       System Administration							LOSETUP(8)

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 <>, based on original version from Theodore Ts'o <> AVAILABILITY
The losetup command is part of the util-linux package and is available from util-linux July 2003 LOSETUP(8)
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