Add git-ref script to print current git reference

This script determines the current git reference type and prints the branch or tag name based on the repository state.

description from copilot

Author: jonpugh

src/git-ref

@@ -0,0 +1,47 @@
+#!/usr/bin/env bash
+usage() {
+  echo -n "git-ref [OPTION]... [FILE]...
+
+Prints the branch or tag of the current git repository.
+
+  -t, --type    Print the git reference type ('branch' or 'tag').
+
+If PWD is tracking a branch, print "branch".
+If PWD is in a DETACHED HEAD state, and there is a tag for the SHA, print "tag".
+If the PWD is in a DETACHED HEAD state, and there is no tag, exit with an error.
+"
+}
+
+BRANCH=`git symbolic-ref --quiet --short HEAD 2> /dev/null`
+TAG=`git describe --tags --exact-match 2> /dev/null`
+
+# Set up options for --type and --help.
+while [ $# -gt 0 ]; do
+  case "$1" in
+    -t|--type)
+        if [[ -n $BRANCH ]]; then
+          echo "branch"
+        elif [[ -n $TAG ]]; then
+          echo "tag"
+        else
+          exit 1
+        fi
+
+        exit 0
+      ;;
+    -h|--help) usage >&2; exit 0;;
+    *)
+      echo "Invalid option: $1"
+      exit 1
+  esac
+  shift
+done
+
+# Print the branch or tag name
+if [[ -n $BRANCH ]]; then
+  echo $BRANCH
+elif [[ -n $TAG ]]; then
+  echo $TAG
+else
+  exit 1
+fi