pwcrypt is a command line interface to the crypt() function.
Here is an example for usage:
bash# pwcrypt -h
crypt v 1.2.1 - copyright 2000 A.L.Lambert
Usage: crypt [-mhVqd] [-s salt] password_to_crypt
-m = Employ MD5 encryption.
-q = Quiet mode - for use with 'cleartext | crypt'.
-h = This help message.
-V = Print version info and exit.
-s salt = Specify the salt to use
If you do not supply a password on the command line, you will be prompted for one (unless in quiet mode). All screen output is always done to stderr, allowing you to do things like
'pwcrypt > somefile',
whereby you will be prompted for the password, but all output will be redirected to somefile.
Use in shell scripts like this exmple of a proftpd-adduser script, for adding user accounts to a proftpd installation that uses a separate password file, to allow for a single system UID for ftp logins (note: this script contains little to no error-checking, but is entirely functional).