openssl rand [-out file] [-rand file(s)] [-base64] [-hex] num
The rand command outputs num pseudo-random bytes after seeding the random number generator once. As in other openssl command line tools, PRNG seeding uses the file $HOME/.rnd or .rnd in addition to the files given in the -rand option. A new $HOME/.rnd or .rnd file will be written back if enough seeding was obtained from these sources.
Write to file instead of standard output.
Use specified file or files or EGD socket (see RAND_egd(3)) for seeding the random number generator. Multiple files can be specified separated by a OS-dependent character. The separator is ; for MS-Windows, , for OpenVMS, and : for all others.
Perform base64 encoding on the output.
Show the output as a hex string.