MCOOKIE(1) User Commands MCOOKIE(1)
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 /dev/urandom, /dev/random, or the libc pseudo-random func‐
tions, in this preference order.
OPTIONS
-f, --file file
Use this file as an additional source of randomness. 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.
-V, --version
Display version information and exit.
-h, --help
Display help text and exit.
BUGS
It is assumed that none of the randomness sources will block.
FILES
/dev/urandom
/dev/random
SEE ALSO
X(1), xauth(1), md5sum(1), rand(3)
AVAILABILITY
The mcookie command is part of the util-linux package and is available from Linux Kernel
Archive ⟨ftp://ftp.kernel.org/pub/linux/utils/util-linux/⟩.
util-linux December 2014 MCOOKIE(1)
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