mcookie - generate magic cookies for xauth
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
, or libc pseudo-random
in this preference order.
- -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
- -V, --version
- Display version information and exit.
- -h, --help
- Display help text and exit.
It is assumed that none of the randomness sources will block.
The mcookie command is part of the util-linux package and is available from