Encoding and decoding with base64, hex, etc on command line

echo 'test' | base64
echo 'dGVzdAo=' | base64 -d

echo 'test' | xxd -p
echo '746573740a' | xxd -p -r

echo 'test' | tr 'A-Za-z' 'N-ZA-Mn-za-m'
echo 'grfg' | tr 'A-Za-z' 'N-ZA-Mn-za-m'