GnuPG (gpg)
Table of Contents
1. Symmetric encryption
Encrypt FILE with a passphrase (use --no-symkey-cache to not cache the passphrase)
gpg --no-symkey-cache [-c,--symmetric] FILE
Decrypt FILE (specify OUTPUT file otherwise the command print FILE content to stdout)
gpg --no-symkey-cache [-o,--output] OUTPUT [-d,--decrypt] FILE