Tools

Base64 encoding / decoding

Encoding / decoding files

base64 inputfile.txt > encodedfile # encode a file
base64 -d encodedfile > outputfile.txt # decode a file

Encoding / decoding strings

echo 'some-string' | base64 # encode a string
echo 'base64-string' | base64 -d # decode a string

Substrings in Bash

Extracting a Substring in Bash describes both index-based and pattern-based substring extractions.