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Section: MAINTENANCE COMMANDS (8)
Updated: Nov 24 1993
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NAMElosetup - set up and control loop devices
SYNOPSISlosetup [ -e encryption ] [ -o offset ] loop_device file
losetup [ -d ] loop_device
DESCRIPTIONlosetup 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.
- detach the file or device associated with the specified loop device.
- -e encryption
enable data encryption. The following keywords are recognized:
- use no encryption (default).
- use a simple XOR encryption.
- use DES encryption. DES encryption is only available if the optional DES package has been added to the kernel. DES encryption uses an additional start value that is used to protect passwords against dictionary attacks.
- enable data encryption. The following keywords are recognized:
- -o offset
- the data start is moved offset bytes into the specified file or device.
RETURN VALUElosetup 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.
/dev/loop0,/dev/loop1,... loop devices (major=7)
EXAMPLEIf you are using the loadable module you must have the module loaded first with the command
- # insmod loop.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
RESTRICTIONDES encryption is painfully slow. On the other hand, XOR is terribly weak.
Original version: Theodore Ts'o <[email protected]> Original DES by: Eric Young <[email protected]>
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