Add shell flags and set long options

templates/skeleton.sh

@@ -7,12 +7,29 @@
 #
 # !!DATE!!
 # }}}
+# Flags {{{
+## Exit on error {{{
+set -o errexit
+## }}}
+## Exit on unset var {{{
+### Use "${VARNAME-}" to test a var that may not have been set
+set -o nounset
+## }}}
+## Pipeline command is treated as failed {{{
+### Not available in POSIX sh − https://github.com/koalaman/shellcheck/wiki/SC3040
+#set -o pipefail
+## }}}
+## Help with debugging {{{
+### Call the script by prefixing it with "TRACE=1 ./script.sh"
+if [ "${TRACE-0}" -eq 1 ]; then set -o xtrace; fi
+## }}}
+# }}}
 # Vars {{{
 PROGNAME=$(basename "${0}"); readonly PROGNAME
-PROGDIR=$(readlink -m $(dirname "${0}")); readonly PROGDIR
+PROGDIR=$(readlink --canonicalize-missing $(dirname "${0}")); readonly PROGDIR
 ARGS="${*}"; readonly ARGS
 readonly NBARGS="${#}"
-[ -z "${DEBUG}" ] && DEBUG=1
+[ -z "${DEBUG-}" ] && DEBUG=1
 ## Export DEBUG for sub-script
 export DEBUG
 
@@ -43,7 +60,6 @@ OPTIONS :
     -h,--help
         Print this help message.
 HELP
-
 }
 # }}}
 debug_message() {                                               # {{{
@@ -64,7 +80,9 @@ error_message() {                                               # {{{
 	local_error_code="${2}"
 
 	## Print message
-	printf '%b\n' "ERROR − ${PROGNAME} : ${RED}${local_error_message}${RESET}"
+	printf '%b\n' "ERROR − ${PROGNAME} : ${RED}${local_error_message}${RESET}" >&2
+
+	unset local_error_message
 
 	exit "${local_error_code:=66}"
 }
@@ -72,13 +90,12 @@ error_message() {                                               # {{{
 define_vars() {                                                 # {{{
 
 	## If my_var_xy wasn't defined (argument) {{{
-	#if [ -z "${my_var_xy}" ]; then
+	#if [ -z "${my_var_xy-}" ]; then
 		### Use default value
 		#readonly my_var_xy="${MY_VAR_XY_DEFAULT}"
 	#fi
 	## }}}
 
-
 	true; ## Remove me
 }
 # }}}
@@ -108,8 +125,15 @@ if [ ! "${NBARGS}" -eq "0" ]; then
 
 	manage_arg="0"
 
+	## If the first argument ask for help (h|help|-h|-help|-*h|-*help) {{{
+	if printf -- '%s' "${1-}" | grep --quiet --extended-regexp -- "^-*h(elp)?$"; then
+		usage
+		exit 0
+	fi
+	## }}}
+
 	## If the first argument is not an option
-	if ! printf -- '%s' "${1}" | grep -q -E -- "^-+";
+	if ! printf -- '%s' "${1}" | grep --quiet --extended-regexp -- "^-+";
 	then
 		## Print help message and exit
 		printf '%b\n' "${RED}Invalid option: ${1}${RESET}"
@@ -120,18 +144,13 @@ if [ ! "${NBARGS}" -eq "0" ]; then
 	fi
 
 	# Parse all options (start with a "-") one by one
-	while printf -- '%s' "${1}" | grep -q -E -- "^-+"; do
+	while printf -- '%s' "${1-}" | grep --quiet --extended-regexp -- "^-+"; do
 
 	case "${1}" in
 		-d|--debug )                          ## debug
 			DEBUG=0
 			debug_message "--- Manage argument BEGIN"
 			;;
-		-h|--help )                           ## help
-			usage
-			## Exit after help informations
-			exit 0
-			;;
 		#-v|--var )                            ## Define var with given arg
 			### Move to the next argument
 			#shift