Info is the standard documentation format for all GNU software. It is a very useful command-line document viewing format, fully equipped with links between the various pages and menus and search capabilities. As explained before, the best thing about it is that it is available for you the moment you need to refresh your memory on any command-line tool in the middle of your work without having to take your hands off the keyboard. This complete book is available in Info format and can be accessed from anywhere on the command-line.
To open the Info format of any installed programs or library on your system which has an Info format book, you can simply run the command below (change
executablename to the executable name of the program or library):
$ info executablename
In case you are not already familiar with it, run
$ info info.
It does a fantastic job in explaining all its capabilities itself.
It is very short and you will become sufficiently fluent in about half an hour.
Since all GNU software documentation is also provided in Info, your whole GNU/Linux life will significantly improve.
Once you’ve become an efficient navigator in Info, you can go to any part of this book or any other GNU software or library manual, no matter how long it is, in a matter of seconds. It also blends nicely with GNU Emacs (a text editor) and you can search manuals while you are writing your document or programs without taking your hands off the keyboard, this is most useful for libraries like the GNU C library. To be able to access all the Info manuals installed in your GNU/Linux within Emacs, type Ctrl-H + i.
To see this whole book from the beginning in Info, you can run
$ info gnuastro
If you run Info with the particular program executable name, for example astcrop or astnoisechisel:
$ info astprogramname
you will be taken to the section titled “Invoking ProgramName” which explains the inputs and outputs along with the command-line options for that program. Finally, if you run Info with the official program name, for example, Crop or NoiseChisel:
$ info ProgramName
you will be taken to the top section which introduces the program. Note that in all cases, Info is not case sensitive.