CODEWITHSUNDEEP
linuxbash
ncrocfer
ncrocfer

Reputation: 2570

Bash : Add an option to an existing command

Is it possible to add an option to an existing Bash command?

For example I would like to run a shell script when I pass -foo to a specific command (cp, mkdir, rm...).

Upvotes: 3

Views: 3557

Answers (2)

Kukuster
Kukuster

Reputation: 184

Some programmer dude's code may look cool and attractive... but you should use it very carefully for most commands: https://unix.stackexchange.com/questions/41571/what-is-the-difference-between-and

About usage of $* and $@:

You shouldn't use either of these, because they can break unexpectedly as soon as you have arguments containing spaces or wildcards.

I was using this myself for at least months until I realized it was the reason why my bash code sometimes didn't work.

Consider much more reliable, but less easy and less portable option. As pointed out in comments, recompile original command with changes, that is:

Download c/c++ source code from some respected developers repositories:

Add some code in c/c++, compile with gcc/g++.

Also, I guess, you can edit bash itself to set it to check if a string passed to bash as a command matches some pattern, don't execute this and execute some different command or a bash script

If you really are into this idea of customizing and adding functionality to your shell, maybe check out some other cool fashionable shells like zsh, fish, probably they have something, I don't know.

Upvotes: 0

Some programmer dude
Some programmer dude

Reputation: 409166

You can make an alias for e.g. cp which calls a special script that checks for your special arguments, and in turn call the special script:

$ alias cp="my-command-script cp $*"

And the script can look like

#!/bin/sh

# Get the actual command to be called
command="$1"
shift

# To save the real arguments
arguments=""

# Check for "-foo"
for arg in $*
do
    case $arg in
    -foo)
        # TODO: Call your "foo" script"
        ;;
    *)
        arguments="$arguments $arg"
        ;;
esac
done

# Now call the actual command
$command $arguments

Upvotes: 6

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