mcookie(1) -- Linux man page
NAMEmcookie - generate magic cookies for xauth
SYNOPSISmcookie [-v] [-f filename ]
DESCRIPTIONmcookie 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 various piece of random information: the current time, the process id, the parent process id, the contents of an input file (if -f is specified), and several bytes of information from the first of the following devices which is present: /dev/random, /dev/urandom, files in /proc, /dev/audio.
BUGSThe entropy in the generated 128-bit is probably quite small (and, therefore, vulnerable to attack) unless a non-pseudorandom number generator is used (e.g., /dev/random under Linux).
SEE ALSOX(1), xauth(1), md5sum(1)