95 lines
2.2 KiB
Groff
95 lines
2.2 KiB
Groff
.TH LOSETUP 8 "Nov 24 1993" "Linux" "MAINTENANCE COMMANDS"
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.SH NAME
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losetup \- set up and control loop devices
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.SH SYNOPSIS
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.ad l
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.B losetup
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[
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.B \-e
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.I encryption
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] [
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.B \-o
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.I offset
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]
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.I loop_device file
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.br
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.B losetup
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[
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.B \-d
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]
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.I loop_device
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.ad b
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.SH DESCRIPTION
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.B losetup
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is used to associate loop devices with regular files or block devices,
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to detach loop devices and to query the status of a loop device. If only the
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\fIloop_device\fP argument is given, the status of the corresponding loop
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device is shown.
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.SH OPTIONS
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.IP \fB\-d\fP
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detach the file or device associated with the specified loop device.
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.IP "\fB\-e \fIencryption\fP"
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.RS
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enable data encryption. The following keywords are recognized:
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.IP \fBNONE\fP
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use no encryption (default).
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.PD 0
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.IP \fBXOR\fP
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use a simple XOR encryption.
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.IP \fBDES\fP
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use DES encryption. DES encryption is only available if the optional
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DES package has been added to the kernel. DES encryption uses an additional
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start value that is used to protect passwords against dictionary
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attacks.
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.PD
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.RE
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.IP "\fB\-o \fIoffset\fP"
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the data start is moved \fIoffset\fP bytes into the specified file or
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device.
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.SH RETURN VALUE
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.B losetup
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returns 0 on success, nonzero on failure. When
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.B losetup
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displays the status of a loop device, it returns 1 if the device
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is not configured and 2 if an error occurred which prevented
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.B losetup
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from determining the status of the device.
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.SH FILES
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.nf
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/dev/loop0,/dev/loop1,... loop devices (major=7)
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.fi
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.SH EXAMPLE
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If you are using the loadable module you must have the module loaded
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first with the command
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.IP
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# insmod loop.o
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.LP
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The following commands can be used as an example of using the loop device.
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.nf
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.IP
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dd if=/dev/zero of=/file bs=1k count=100
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losetup -e des /dev/loop0 /file
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Password:
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Init (up to 16 hex digits):
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mkfs -t ext2 /dev/loop0 100
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mount -t ext2 /dev/loop0 /mnt
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...
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umount /dev/loop0
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losetup -d /dev/loop0
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.fi
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.LP
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If you are using the loadable module you may remove the module with
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the command
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.IP
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# rmmod loop
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.LP
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.fi
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.SH RESTRICTION
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DES encryption is painfully slow. On the other hand, XOR is terribly weak.
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.SH AUTHORS
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.nf
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Original version: Theodore Ts'o <tytso@athena.mit.edu>
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Original DES by: Eric Young <eay@psych.psy.uq.oz.au>
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.fi
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