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() 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.

       -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

       md5sum(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/⟩.