The modifiable sources of the original book (in english), are available in LyX format (LyX Document Processor) or Machine-translated SGML (SGML markup language).
LyX is a completely free document processor based on LaTeX, downloadable from the LyX homepage..
See for the modifiable sources of this document. These are the official versions. We (the translators and current maintainers) plan to continue work on this document and add new chapters and enhancements. If you want to see the version we are currently working on (the "bleeding edge" version), check the GNU/Linux Command-Line Tools Summary Homepage from time to time (kindly hosted by Chris Karakas).