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Paul Erlenmeyer
Asked: 2019-12-05 03:11:13 +0800 CST

Where to find the code for the terminal commands?

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I want to be able to see the code that gets executed whenever I type 'ls' or 'cd' in my terminal. With that I would like to get into modifying existing programs and writing new ones. In what language are those programs written?

command-line source-code

1 Answers

  1. Best Answer

    Where to find the code for the terminal commands?

    Where to find it depends on the command. There are several locations.

    Regarding the two you mention:

    GNU coreutils

    ls is part of GNU Coreutils. You can get the source code for all the GNU core utilities (so not just for ls: wikipedia list of core utilities) on www.gnu.org. From the command line using git (git needs to be installed): 

    git clone git://git.sv.gnu.org/coreutils

    The source for ls can also be found online on git.savannah.gnu.org. All the other commands are accessible there too.

    • Shell builtins

    cd is a built-in in the shell so is part of bash. You can find the source code for bash on ftp.gnu.org. That will also be the source code for all builtins.

    bash defines the following built-in commands: :, ., [, alias, bg, bind, break, builtin, case, cd, command, compgen, complete, continue, declare, dirs, disown, echo, enable, eval, exec, exit, export, fc, fg, getopts, hash, help, history, if, jobs, kill, let, local, logout, popd, printf, pushd, pwd, read, readonly, return, set, shift, shopt, source, suspend, test, times, trap, type, typeset, ulimit, umask, unalias, unset, until, wait, while.

    In what language are those programs written?

    C or C++

    With that I would like to get into modifying existing programs and writing new ones

    You are better off using the existing tools and adding to them: create a script called ls2 and then add functionality to that script to mimic ls + your additions. Your additions could be extra letters as parameters that trigger functions. Biggest advantage: you can write it in the language you prefer. Safer since you do not mess with the normal commands if your intention is to code new functionality for your these tools you should join their respective mailing lists.

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