MCOOKIE

Section: User Commands (1)
Updated: March 2014
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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 output of the MD5 message digest fed with random information from one of the sources /dev/urandom, /dev/random, or libc pseudo-random functions in this preference order.

OPTIONS

-f, --file=FILE: Use additional file as a macig cookie random seed. When file is defined as '-' character input is read from stdin.
-m, --max-size=number: Read form FILE only number of bytes. This option is meant to be used when reading additional randomness from a 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

AVAILABILITY

The mcookie command is part of the util-linux package and is available from Linux Kernel Archive