argparse-completion.bash

#/usr/bin/env bash

function _completions() {
	COMPREPLY+=("-e")
	COMPREPLY+=("--echo")
	COMPREPLY+=("--some-flag")
	COMPREPLY+=("-c")
	COMPREPLY+=("--non-interactive")
	COMPREPLY+=("--")
}

complete -F _completions argparse.sh

argparse.sh

#!/bin/bash

usage="$(basename "$0") [OPTIONS] -- example program

[OPTIONS]:
	-h|--help		Halp
	-e|--echo		Text to echo
	--some-flag 		Some flag to set, --some-flag without any parameters and you'll see
	-c			Something else to echo
	--non-interactive	Do not prompt for confirmation
	--			End of options, pass anything
"

# $# represents the number of arguments
echo "\$\# value is $#"

if [[ $# == 0 ]]; then
	echo "$usage"
	exit
fi

function proceed() {
	echo "Would you like to proceed? Yn"
	read choice

	case $choice in
	[Yy]*) echo "your choice is yes";;
	[Nn]*) echo "your choice is no"; exit;;
	esac
}

while [[ $# -gt 0 ]]; do
	key="$1"

	case $key in
	-h|--help)
		echo "$usage"
		exit
		;;
	-e|--echo)
		TEXT_TO_ECHO=$2
		# use shift to do this weird parameters dance: http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_09_07.html
		shift
		shift
		;;
	-c)
		SOMETHING_ELSE_TO_ECHO=$2
		shift
		shift
		;;
	--some-flag)
		FLAG=true
		# Use one shift for the flag
		shift
		;;
	--non-interactive)
		NON_INTERACTIVE=true
		shift
		;;
	--)
		echo "End of options"
		shift
		break
		;;
	esac
done

SCRIPT=$@

echo "Whatever comes after --: $SCRIPT"
if [ -z "$NON_INTERACTIVE" ]; then
	proceed
fi

if [ "$SCRIPT" ]; then
	echo "Running $SCRIPT"
	eval "$SCRIPT"
fi

if [ $FLAG ]; then
	echo "Flag set"
fi

if [ -z "$SOMETHING_ELSE_TO_ECHO" ]; then
	SOMETHING_ELSE_TO_ECHO=somedefaulttext
fi

echo $TEXT_TO_ECHO
echo $SOMETHING_ELSE_TO_ECHO