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.
It is possible to specify transfer functions (for encryption/decryption
or other purposes) using one of the
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 wil take the name of an arbitrary encryption type
and finds the module that knows how to perform that encryption.
(Thus, either one uses a number different from 18 with the
option, or one uses a name with the
Show status of all loop devices.
Detach the file or device associated with the specified loop device.
Enable data encryption with specified number.
Enable data encryption with specified name.
Find the first unused loop device. If a
argument is present, use this device. Otherwise, print its name.
The data start is moved offset bytes into the specified file or
Read the passphrase from file descriptor with number
instead of from the terminal.
Setup read-only loop device.
returns 0 on success, nonzero on failure. When
displays the status of a loop device, it returns 1 if the device
is not configured and 2 if an error occurred which prevented
from determining the status of the device.