MCOOKIE(1) User Commands MCOOKIE(1)NAMEmcookie - generate magic cookies for xauth
SYNOPSISmcookie [options]
DESCRIPTIONmcookie 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 functions, 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 suf‐
fixes 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 mean‐
ing 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 ALSOmd5sum(1), X(1), xauth(1), rand(3)AVAILABILITY
The mcookie command is part of the util-linux package and is available
from Linux Kernel Archive ⟨https://www.kernel.org/pub/linux/utils/util-
linux/⟩.
util-linux December 2014 MCOOKIE(1)
