'Write-in' is my phrase for what the FSF and FLOSS Manuals are up to. They're running a community project "to collaboratively produce a new free software textbook for GNU/Linux users." This book will be focusing on the BASH shell.
The project is well under way, but in what the FSF is calling a 'sprint,' they're planning on doing a lot of the work during this weekend's, March 21st-22nd, GNU/Linux conference LibrePlanet. FLOSS Manuals' Adam Hyde said in a statement that, "This is an exciting opportunity to work with the FSF and help build a sustainable model for the production of more textbooks for free software users. I encourage volunteers to start contributing text and ideas immediately. This new book will be available online for free download immediately after LibrePlanet finishes on Monday, March 23, and two hundred copies will be available for sale in book form from the FSF web site."
In a statement, FSF executive director Peter Brown said, "By purchasing a copy of this new book, supporters can help kick start the production cycle of additional freely licensed, community-written texts for free software. We also hope that our collaboration with FLOSS Manuals will encourage more volunteer authors to participate in the production free software documentation."
This sounds like a good idea that could go terribly wrong, but I have every expectation that they will make their deadline and the book will be great. That's because Andy Oram, an O'Reilly editor and a guy who's written more than his fair share of great Linux and open-source books, is the editor-in-chief of the project.
Needless to say, for a FSF production, the text will be available under both the GNU GPL (General Public License) and the GNU Free Documentation License.
So, if you want to learn about the differences between relative and absolute paths and why the command 'rm -rf' is usually the dumbest thing you could ever do on a Linux or Unix computer, this will be the book for you. If, however, you want to help explain, say, the differences between the '&&' and '||' constructs, visit the "Introduction to the Command Line" project page.