libencode.sh

Base64 family of binary-to-text encoding algorithms implemented in shell.

Contents

1. Libraries
2. Compatibility
3. Requirements
4. Demo
5. License

Libraries

• encode.sh is a general purpose library exposing various functionalities like conversion from decimal to binary or string padding. It exports the following functions:
  • enum
  • leftpad
  • rightpad
  • ord
  • chr
  • dectobin
  • bintodec
  • dectohex
  • swap32
• base64.sh implements the Base64, Base64 URL, Base32, Base32 Hex and Base16 encoding algorithms. The following functions are considered public:
  • base64_encode
  • base64url_encode
  • base32_encode
  • base32hex_encode
  • base16_encode
  • hex_encode

Compatibility

libencode.sh targets shells supporting the KSH “local” extension. It is therefore known to run with the following shells:

• Debian Almquist SHell - dash ;
• GNU Bourne-Again SHell - bash ;
• MirBSD Korn SHell - mksh ;
• OpenBSD Korn SHell - oksh ;
• Yet Another SHell - yash.

Additionally zsh is fully compatible with encode.sh but doesn't work well with base64.sh. In both case the option SH_WORD_SPLIT must be activated.

Requirements

The following utilities are needed by libencode:

• printf (built-in shell version is fine) ;
• bc ;
• cut ;
• grep ;
• jot or seq ;
• sed.

Demo

A simple script wrapping all of the binary-to-text functions is provided: demo.sh. It is a Korn Shell script using the autoload feature, so a directory populated with a file for every functions exported by libencode and a correct FPATH environnement variable are mandatory :

$ mkdir -p ~/sh
$ cd ~/sh
$ ln -s $LIBENCODEPATH/base64.sh base16_encode
$ ln -s $LIBENCODEPATH/base64.sh hex_encode
$ ln -s $LIBENCODEPATH/base64.sh base32_encode
$ ln -s $LIBENCODEPATH/base64.sh base32hex_encode
$ ln -s $LIBENCODEPATH/base64.sh base64_encode
$ ln -s $LIBENCODEPATH/base64.sh base64url_encode
$ grep -E '^[a-z0-9]+\(' $LIBENCODEPATH/encode.sh | while read func; do
> func="$(echo $func | cut -d'(' -f1)";
> ln -s $LIBENCODEPATH/encode.sh "$func";
> done
$ export FPATH=$FPATH:$HOME/sh

The environnement is now ready, demo.sh is usable :

$ mksh $LIBENCODEPATH/demo.sh -e base64 -s foobar
Zm9vYmFy
$ echo -n foobar | base64
Zm9vYmFy

It is also possible to use autoload in an interactive korn shell to use base64_encode directly :

$ autoload base64_encode
$ base64_encode foobar
Zm9vYmFy

Of course all of these awkward steps can be bypassed if you just this project as intended: as a library.

License

All the code is licensed under the ISC License. It's free, not GPLed !