GnuGP

Encrypt a file with a passphrase

gpg -o file.txt.gpg -c file.txt 

Note: -c is equivalent to --symmetric

Encrypt a list of files, with passphrase from file

ls *.tar.gz | xargs -I{} gpg --passphrase-file gpg.secret --symmetric --batch --yes {}

Show encryption used in a gpg file

gpg --list-packets -vv --show-session-key file.gpg

source

Show fingerprint of private key with no import

gpg --with-colons --import-options show-only --import --fingerprint < secret.asc | awk -F: '$1 == "fpr" {print $10;}'

source

Show a gpg file in armored format

gpg --enarmor < file.gpg