Bash Argument Parsing
After working with great libraries like NodeJS's minimist, I sometimes find it hard to go back to other languages where things take a very "reimplement it every time you need it" or a "this works, but not in case XYZ" approach.
I was faced with this problem yet again when developing some wrapper scripts for docker swarm: I can do simple argument-matching in bash, but that's order-dependent, and only supports opt-in flags.
Introducing bash-minimist
So, under the inspiration of NodeJS minimist, I developed bash-minimist: A simple and opinionated script that will export flags, values, and positional arguments through variables, and let your script handle the rest. It's not documentation (Doesn't implement --help for you), nor is it error-checking (it will happily let most values through).
Example
#!/bin/bash
# This is all you have to do to use it
# Once used, all flags will be removed from $@ (Not in $1 $2, etc..)
# And all arguments and values will be declared under ARG_ (by default)
source minimist.sh
if [[ $ARG_n == 'y' ]]; then
echo "-y" was set
fi
if [[ $ARG_k == 'y' ]]; then
echo "-k was set"
fi
echo "Positionals $1 $2 $3"
echo "Flags: ABC=$ARG_ABC"
Alright, the above is a nieve example, but now you can do this:
$ ./example -y -k --abc=123 pos1 pos2 pos3
# OR THIS
$ ./example pos1 pos2 -yk --abc=123 pos3
# OR THIS
$ ./example -yk --abc=123 -- pos1 pos2 --pos3
Help-text
My pattern providing help looks like this:
#!/bin/bash
function abortHelp() {
echo "Usage:"
echo " $0 <positional1> [flags]"
echo " -h --help Show this help"
echo " -t --tun Create tunnel"
exit 1
}
source minimist.sh
if [[ $ARG_h == 'y' || $ARG_HELP == 'y' ]]; then
abortHelp
fi
if [[ -z $1 ]]; then
echo "Required pos arg 1"
abortHelp
fi
if [[ $ARG_t == 'y' || $ARG_TUN == 'y' ]]; then
echo "You want a tunnel"
fi
echo "Tunneling to $1"
Getting started
Simply head over to bash-minimist, download minimist.sh, and source it in your script today!
wget -O minimist.sh https://raw.githubusercontent.com/zix99/bash-minimist/master/minimist.sh