mcookie man page

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 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 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.

Info

December 2014 util-linux User Commands