Manpages - mcookie.1

mcookie - generate magic cookies for xauth

mcookie [options]

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*=(2) system call, //dev/urandom/, //dev/random/, or the =/libc pseudo-random functions/=, in this preference order. See also the option *--file*.=

-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.

-h*=, =–help*

Display help text and exit.

-V*=, =–version*

Print version and exit.

/dev/urandom

/dev/random

It is assumed that none of the randomness sources will block.

*md5sum*=(1),= *X*=(7),= *xauth*=(1),= *rand*=(3)=

For bug reports, use the issue tracker at <https://github.com/util-linux/util-linux/issues>.

The *mcookie*= command is part of the util-linux package which can be downloaded from = Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>.