decode/encode base64 string

• base64 program from the coreutils package:

echo QWxhZGRpbjpvcGVuIHNlc2FtZQ== | base64 --decode

• openssl

$ openssl enc -base64 <<< 'Hello, World!'
SGVsbG8sIFdvcmxkIQo=

$ openssl enc -base64 -d <<< SGVsbG8sIFdvcmxkIQo=
Hello, World!

• python base64 module

echo $1 | python -m base64 -d