Add 'Parse command line options.sh'

Parse command line options.sh

@@ -0,0 +1,24 @@
+# Parse command line options
+# =========================================================================== #
+# This is an example script for using both long and short flags without using getopt (which is nonstandard)
+# Copy paste from 
+#   https://stackoverflow.com/questions/402377/using-getopts-to-process-long-and-short-command-line-options
+
+die() { echo "$*" >&2; exit 2; }  # complain to STDERR and exit with error
+needs_arg() { if [ -z "$OPTARG" ]; then die "No arg for --$OPT option"; fi; }
+
+while getopts ab:c-: OPT; do
+  if [ "$OPT" = "-" ]; then   # long option: reformulate OPT and OPTARG
+    OPT="${OPTARG%%=*}"       # extract long option name
+    OPTARG="${OPTARG#$OPT}"   # extract long option argument (may be empty)
+    OPTARG="${OPTARG#=}"      # if long option argument, remove assigning `=`
+  fi
+  case "$OPT" in
+    a | alpha )    ALPHA=true ;;
+    b | bravo )    needs_arg; BRAVO="$OPTARG" ;;
+    c | charlie )  CHARLIE=true ;;
+    ??* )          die "Illegal option --$OPT" ;;  # bad long option
+    \? )           exit 2 ;;  # bad short option (error reported via getopts)
+  esac
+done
+shift $((OPTIND-1)) # remove parsed options and args from $@ list