bash script parameters

Question

I need to write a bash script, and would like it to parse unordered parameters of the format:

scriptname --param1 <string> --param2 <string> --param3 <date>

Is there a simple way to accomplish this, or am I pretty much stuck with $1, $2, $3?

Answer 1

You want getopts.

Answer 2

Bash has a getops function, as mentioned here before, that might solve your problems.

If you need anything more sophisticated, bash also supports positional parameters (ordered $1 ... $9, and then ${10} .... ${n}), you'll have to come up with your own logic to handle this input. One easy way to go is to put a switch/case inside of a for loop, iterating over the parameters. You can use either one of the two special bash vars that handle the input: $* or $@.

Answer 3

while [[ $1 = -* ]]; do
    arg=$1; shift           # shift the found arg away.

    case $arg in
        --foo)
            do_foo "$2"
            shift           # foo takes an arg, needs an extra shift
            ;;
        --bar)
            do_bar          # bar takes no arg, doesn't need an extra shift
            ;;
    esac
done

Answer 4

A nice example of how to implement short & long switches side by side is mcurl:

http://www.goforlinux.de/scripts/mcurl/

Cheers,

jon