Retab is a small command line utility that allows you to reformat ASCII text files so that the tab characters represent a different number of characters. It can reformat text for new tab size, convert all tabs into spaces or it can convert spaces into tabs.
I wrote this a long time ago when I had a printer which printed out tabs as 8 spaces. This meant that I couldn’t use this printer with some files in which tabs represented a different number of spaces. Retab allowed me to print these files with that printer.
This program is free! The source code has been released to public domain (Open Source) so feel free to use it however you like. You can download it from the Retab project at SourceForge.
If you just want to see what it does, you can read the user manual.