Man page - rpi-loop-device-namer(8)

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Package: rpi-loop-utils
apt-get install rpi-loop-utils

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rpi-loop-utils

Manual

RPI-LOOP-DEVICE-NAMER

NAME
SYNOPSIS
DESCRIPTION
ARGUMENTS
OUTPUT
EXAMPLES
Loop device with backing file /var/swap:
Loop device with backing file /home/pi/disk.img:
Unbound loop device:
FILES
SEE ALSO
NOTES

NAME

rpi-loop-device-namer - generate stable names for loop device symlinks

SYNOPSIS

rpi-loop-device-namer MINOR_NUMBER

DESCRIPTION

rpi-loop-device-namer is a utility script that generates stable symbolic link names for loop devices based on their backing files. It is primarily intended to be called by udev rules to create persistent device names.

The script takes a loop device minor number as input and outputs a systemd-escaped path suitable for use in /dev/disk/by-backingfile/ symlinks.

ARGUMENTS

MINOR_NUMBER

The minor device number of the loop device (e.g., "0" for /dev/loop0, "1" for /dev/loop1).

OUTPUT

If the specified loop device has an associated backing file, the script outputs:
disk/by-backingfile/ ESCAPED_PATH

Where ESCAPED_PATH is the systemd-escaped version of the backing file path.

If the loop device has no backing file, no output is produced.

EXAMPLES

Loop device with backing file /var/swap:

$ rpi-loop-device-namer 0
disk/by-backingfile/var-swap

Loop device with backing file /home/pi/disk.img:

$ rpi-loop-device-namer 1
disk/by-backingfile/home-pi-disk.img

Unbound loop device:

$ rpi-loop-device-namer 2
(no output)

FILES

/usr/lib/rpi-loop-utils/bin/rpi-loop-device-namer

The script itself.

/sys/block/loopN/loop/backing_file

Kernel sysfs file containing the backing file path for loop device N.

NOTES

This utility is typically called automatically by udev rules and is not intended for direct interactive use. The output format is specifically designed for use with udev’s SYMLINK+= directive.