Created
May 11, 2024 08:06
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Bash argument parsing example
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#!/bin/bash | |
set -o errexit # Fail and exit the script immediately if any command fails | |
set -o nounset # Throw an error if there are unset variables | |
# Parse arguments (based on https://stackoverflow.com/questions/192249/how-do-i-parse-command-line-arguments-in-bash) | |
HARD="false" | |
VERBOSE="false" | |
usage_error () { echo >&2 "$(basename ${0}): ${1}"; exit 2; } | |
assert_argument () { test "${1}" != "${EOL}" || usage_error "${2} requires an argument"; } # TODO: Force boolean | |
if [ "${#}" != 0 ]; then | |
EOL=$(printf '\1\3\3\7') | |
set -- "${@}" "${EOL}" | |
while [ "${1}" != "${EOL}" ]; do | |
OPT="${1}"; shift | |
case "${OPT}" in | |
-h|--help) | |
echo | |
echo "Usage: ${0} (options)" | |
echo | |
echo "Options:" | |
echo " -a, --hard Hard reset, wiping all persisted user data" | |
echo " -v, --verbose Provide extra output to aid debugging" | |
echo | |
exit 1 | |
;; | |
# Variables | |
-a|--hard ) HARD="true";; | |
-v|--verbose ) VERBOSE="true";; | |
# Arguments processing. You may remove any unneeded line after the 1st. | |
-|''|[!-]*) set -- "${@}" "${OPT}";; # positional argument, rotate to the end | |
--*=*) set -- "${OPT%%=*}" "${OPT#*=}" "$@";; # convert '--name=arg' to '--name' 'arg' | |
-[!-]?*) set -- $(echo "${OPT#-}" | sed 's/\(.\)/ -\1/g') "$@";; # convert '-abc' to '-a' '-b' '-c' | |
--) while [ "${1}" != "${EOL}" ]; do set -- "$@" "${1}"; shift; done;; # process remaining arguments as positional | |
-*) usage_error "unknown option: '${OPT}'";; # catch misspelled options | |
*) usage_error "this should NEVER happen (${OPT})";; # sanity test for previous patterns | |
esac | |
done | |
shift | |
fi | |
# Preflight checks | |
if [ ! -z "$@" ]; then # Abort if bad argument given | |
echo "Unexpected arguments '${@}'" >&2 | |
exit 1 | |
fi |
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