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MCOOKIE

Section: User Commands (1)
Updated: 202-1-15
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NAME

mcookie - generate magic cookies for xauth

SYNOPSIS

mcookie [options]

DESCRIPTION

mcookie generates a 128-bit random hexadecimal number for use with the X authority system. Typical usage:

: xauth add :0 . mcookie

The "random" number generated is actually the MD5 message digest of random information coming from one of the sources getrandom(2) system call, /dev/urandom, /dev/random, or the libc pseudo-random functions, in this preference order. See also the option --file.

OPTIONS

-f, --file file

: Use this file as an additional source of randomness (for example /dev/urandom). When file is '-', characters are read from standard input.

-m, --max-size number

: Read from file only this number of bytes. This option is meant to be used when reading additional randomness from a file or device.
The number argument may be followed by the multiplicative suffixes KiB=1024, MiB=1024*1024, and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, e.g., "K" has the same meaning as "KiB") or the suffixes KB=1000, MB=1000*1000, and so on for GB, TB, PB, EB, ZB and YB.

-v, --verbose

: Inform where randomness originated, with amount of entropy read from each source.

-h, --help

: Display help text and exit.

-V, --version

: Display version and exit.

FILES

/dev/urandom

/dev/random

BUGS

It is assumed that none of the randomness sources will block.

REPORTING BUGS

For bug reports, use the https://github.com/uti-linux/uti-linux/issues <L>issue tracker

AVAILABILITY

The mcookie command is part of the util-linux package which can be downloaded from https://www.kernel.org/pub/linux/utils/uti-linux/ <L>Linux Kernel Archive