Turn required arguments into optional flags

Thereby add minimal --help option.

This is a breaking change of the command-line interface.

1 files changed, 36 insertions, 10 deletions

diff --git a/temp-postgres.sh b/temp-postgres.sh
index 15e169b..6064b66 100755
--- a/temp-postgres.sh
+++ b/temp-postgres.sh
@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (c) 2019, 2020, 2022 Stefan Kreutz <mail@skreutz.com>
+# Copyright (c) 2019, 2020, 2022, 2026 Stefan Kreutz <mail@skreutz.com>
 #
 # Permission to use, copy, modify, and distribute this software for any purpose
 # with or without fee is hereby granted, provided that the above copyright
@@ -14,7 +14,7 @@
 # OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 # PERFORMANCE OF THIS SOFTWARE.
 
-set -u
+set -o nounset
 
 # Remove the temporary directory before exiting.
 trap 'quit' INT
@@ -30,14 +30,40 @@ quit() {
   exit "${code}"
 }
 
-# Parse arguments.
-[ $# -eq 2 ] || {
-  ( >&2 printf "temp-postgres: invalid arguments\\n" )
-  printf "Usage: temp-postgres <dbname> <username>\\n"
-  quit 1
-}
-dbname="$1"
-username="$2"
+dbname="$( id -un )"
+username="$( id -un )"
+
+while [ $# -gt 0 ] ; do
+  case "$1" in
+    -h|--help)
+      echo "Usage: temp-postgres [-h|--help] [-d|--dbname <dbname>] [-u|--username <username>]"
+      exit
+      ;;
+    -d|--dbname)
+      dbname="$2"
+      shift 2
+      ;;
+    -u|--username)
+      username="$2"
+      shift 2
+      ;;
+    --)
+      shift
+      break
+      ;;
+    -*)
+      ( >&2 echo "undefined option: $1" )
+      exit 2
+      ;;
+    *)
+      break
+      ;;
+  esac
+done
+if [ $# -gt 0 ] ; then
+  ( >&2 echo "too many arguments" )
+  exit 2
+fi
 
 # Create a temporary directory
 tmpdir="$( mktemp -d )" || {