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 output of the MD5 message  digest  fed  with
       random  information from one of the sources /dev/urandom, /dev/random, or libc pseudo-ran‐
       dom 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

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                                  March 2014                                 MCOOKIE(1)