Rechercher une page de manuel
losetup
Langue: en
Version: 51672 (openSuse - 09/10/07)
Section: 8 (Commandes administrateur)
NAME
losetup - set up and control loop devicesSYNOPSIS
Get info:losetup loop_device
losetup -a
Delete loop:
losetup -d loop_device
Print name of first unused loop device:
losetup -f
Setup loop device:
losetup [{-e|-E} encryption] [-o offset] [-p pfd] [-r] {-f[-s]|loop_device} file
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 loop_device argument is given, the status of the corresponding loop device is shown.Encryption
It is possible to specify transfer functions (for encryption/decryption or other purposes) using one of the -E and -e options. There are two mechanisms to specify the desired encryption: by number and by name. If an encryption is specified by number then one has to make sure that the Linux kernel knows about the encryption with that number, probably by patching the kernel. Standard numbers that are always present are 0 (no encryption) and 1 (XOR encryption). When the cryptoloop module is loaded (or compiled in), it uses number 18. This cryptoloop module will take the name of an arbitrary encryption type and finds the module that knows how to perform that encryption.OPTIONS
- -a, --all
- show status of all loop devices
- -d, --detach
- detach the file or device associated with the specified loop device
- -e, -E, --encryption encryption_type
- enable data encryption with specified name or number
- -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
- -o, --offset offset
- The data start is moved offset bytes into the specified file or device.
- -p, --pass-fd num
- Read the passphrase from file descriptor with number num instead of from the terminal
- -r, --read-only
- setup read-only loop device
- -s, --show
- print device name if the -f option and a file argument are present
- -v, --verbose
- verbose mode
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 configured and 2 if an error occurred which prevented losetup from determining the status of the device.FILES
/dev/loop0, /dev/loop1, ... loop devices (major=7)
EXAMPLE
If you are using the loadable module you must have the module loaded first with the command- # insmod loop.o
Maybe also encryption modules are needed.
- # insmod des.o # insmod cryptoloop.o
The following commands can be used as an example of using the loop device.
- # dd if=/dev/zero of=/file bs=1k count=100 # losetup -e des /dev/loop0 /file Password: Init (up to 16 hex digits): # mkfs -t ext2 /dev/loop0 100 # mount -t ext2 /dev/loop0 /mnt ... # umount /dev/loop0 # losetup -d /dev/loop0
If you are using the loadable module you may remove the module with the command
- # rmmod loop
RESTRICTION
DES encryption is painfully slow. On the other hand, XOR is terribly weak.
Cryptoloop is deprecated in favor of dm-crypt. For more details see cryptsetup(8).
AVAILABILITY
The losetup command is part of the util-linux-ng package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.
Contenus ©2006-2023 Benjamin Poulain
Design ©2006-2023 Maxime Vantorre