Bash script template for options parsing

bash_option_parsing.sh

#!/bin/bash
# see http://stackoverflow.com/a/14203146 for more on this
set -e
set -u

###################
# Option Defailts #
###################
opt="option default"
flag=false
verbose=0

###################
# Version & Usage #
###################
VERSION="0.0.0"
USAGE="
$(basename $0) version $VERSION

usage:

    $(basename $0) [options] arg1 [arg2 ...]

options:
    -o, --opt val   set opt to val [$opt]
    -f, --flag      enable flag
    -v, --verbose   increase verbosity
    -h, --help      print this message and exit
    --              options terminator

    DESCRIPTION
"

#################
# Parse Options #
#################
while [[ $1 == -* ]]; do
    case $1 in
        -o|--opt)
            opt="$2"
            shift  # past value
            ;;
        -f|--flag)
            flag=true
            # do not shift again!
            ;;
        -v|--verbose)
            ((verbose+=1))
            # do not shift again!
            ;;
        -h|--help)
            echo "$USAGE"
            exit
            ;;
        --)
            shift
            break
            ;;
        *)
            >&2 echo "$(basename $0): unknown option $1" \
                "(run '$(basename $0) --help' for available options)"
            exit 1
    esac
    shift
done
# all options have been shifted out, so just arguments are left in $@

###############
# Main Script #
###############
echo "opt = $opt"
if [ "$flag" = true ]; then
    echo "flag = enabled ($flag)"
else
    echo "flag = disabled ($flag)"
fi
echo "verbose = $verbose"
i=0
for arg in "$@"; do
    echo "arg $i = $arg"
    ((i+=1))
done