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RedHat 9 (Linux i386) - man page for losetup (redhat section 8)

LOSETUP(8)			       MAINTENANCE COMMANDS			       LOSETUP(8)

NAME
       losetup - set up and control loop devices

SYNOPSIS
       losetup [ -e encryption ] [ -o offset ] loop_device file
       losetup [ -d ] loop_device

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.

OPTIONS
       -d     detach the file or device associated with the specified loop device.

       -e encryption
	      enable data encryption. The following keywords are recognized:

	      NONE   use no encryption (default).
	      XOR    use a simple XOR encryption.
	      DES    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.

       -o offset
	      the data start is moved offset bytes into the specified file or device.

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 com-
       mand

	      # 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

RESTRICTION
       DES encryption is painfully slow. On the other hand, XOR is terribly weak.

AUTHORS
       Original version: Theodore Ts'o <tytso@athena.mit.edu>
       Original DES by: Eric Young <eay@psych.psy.uq.oz.au>

Linux					   Nov 24 1993				       LOSETUP(8)


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