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Mario Palumbo
Asked: 2021-03-03 03:50:26 +0800 CST

bash: compgen -c does not return me the output that I want

  • 772
compgen -c | sort -b | uniq | less

Shows also functions and keywords (luckily no aliases), I instead want all that are not keywords, functions or aliases. In few words only the commands.

If command name match with function name, keyword name or alias name; the command name must not be omitted.

command-line

2 Answers

  1. Best Answer

    For compgen (and I think for Linux in general), a command is everything that you can run including alias' and functions, etc.

    If you want to get only executable files/scripts in any of your $PATH directories, there is no good way using compgen.

    You could use comm to show all commands excluding aliases, keywords and functions:

    comm -23 \
  <(compgen -c | sort -u) \
  <(compgen -akA function | sort -u)

    However, this will also remove commands that are both alias/function and command (e.g. ls or grep have an alias per default in Ubuntu, as well as anything you added yourself).

    So, I think you're better off getting all executables from $PATH with your own script (and if you wish you can add builtins using compgen -b):

    path_filenames(){
  printf '%s' "$PATH" \
  | xargs -d: -I{} -- find -L {} -maxdepth 1 -executable -type f -printf '%P\n' 2>/dev/null
}

sort -u <(path_filenames) <(compgen -b)
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  2. To print aliases, run:

    alias

    To print functions, run:

    declare -F

    or

    declare -f

    To print commands ( excluding aliases, keywords and functions ), run:

    compgen -c | \
grep -wv "$(alias | grep -oP '\w+(?=\=)')"| \
grep -wv "$(declare -F | awk '{print $3}')" | \
grep -wFv "$(compgen -k)"
    • grep -wv "$(alias | grep -oP '\w+(?=\=)')" will exclude aliases.
    • grep -wv "$(declare -F | awk '{print $3}')" will exclude functions.
    • grep -wFv "$(compgen -k)" will exclude keywords.
    • 0