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 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
Print version and exit.
FILES
/dev/urandom
/dev/random
BUGS
It is assumed that none of the randomness sources will block.
SEE ALSO
md5sum(1), X(7), xauth(1), rand(3)
REPORTING BUGS
For bug reports, use the issue tracker at [34mhttps://github.com/util-linux/util-linux/issues.
AVAILABILITY
The mcookie command is part of the util-linux package which can be downloaded from [34mLinux Kernel Archive
<https://www.kernel.org/pub/linux/utils/util-linux/>.
util-linux 2.39 2022-05-11 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 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
Print version and exit.
FILES
/dev/urandom
/dev/random
BUGS
It is assumed that none of the randomness sources will block.
SEE ALSO
md5sum(1), X(7), xauth(1), rand(3)
REPORTING BUGS
For bug reports, use the issue tracker at [34mhttps://github.com/util-linux/util-linux/issues.
AVAILABILITY
The mcookie command is part of the util-linux package which can be downloaded from [34mLinux Kernel Archive
<https://www.kernel.org/pub/linux/utils/util-linux/>.
util-linux 2.39 2022-05-11 MCOOKIE(1)