shell-base64:POSIX Shell的Base64实现

shell-base64 如何使用： $ printf 'Man' | ./encode_base64.sh TWFu $ printf 'TWFu' | ./decode_base64.sh Man $ printf 'Man is distinguished, not only by his reason, but by this singular passion from other animals, which is a lust of the mind, that by a perseverance of delight in the continued and indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure.' | ./encode_base64