improve script. Allow pass either branch or tag on commandline,

defaulting to branch of tree from which called.  Add usage().  set -u
-e and deal with [ -n "$1" ] being an error in that case.

xwords4/android/scripts/arelease_clone.sh

@@ -1,19 +1,55 @@
 #!/bin/sh
 
-BUILDIR=/tmp/$(basename $0)_build_$$
-CURDIR=$(pwd)
-SRCDIR=${CURDIR}/../../../
+set -e -u
 
-echo $BUILDIR
-echo $SRCDIR
-ls $SRCDIR
+usage () {
+    echo "usage: $(basename $0) [--tag tagname | --branch branchname]"
+    echo "   # (uses current branch as default)"
+    exit 0
+}
+
+TAG=""
+BRANCH=""
+
+while [ 0 -lt $# ] ; do
+    case $1 in
+        --tag)
+            TAG=$2
+            shift
+            ;;
+        --branch)
+            BRANCH=$2
+            shift
+            ;;
+        *)
+            usage
+            ;;
+    esac
+    shift
+done
+
+if [ -n "$TAG" ]; then
+    if ! git tag | grep -w "$TAG"; then
+        echo "tag $TAG not found"
+        usage
+    fi
+elif [ -z $BRANCH ]; then
+    BRANCH=$(git branch | grep '^*' | sed 's,^.* ,,')
+fi
+
+echo "building with ${TAG}${BRANCH}"
+
+BUILDIR=/tmp/$(basename $0)_build_$$
+SRCDIR=$(pwd)/$(dirname $0)/../../../
+
+CURDIR=$(pwd)
 
 mkdir -p $BUILDIR
 cd $BUILDIR
 git clone $SRCDIR BUILD
 cd BUILD
-git checkout android_branch 
-./xwords4/android/scripts/arelease.sh $*
+git checkout ${TAG}${BRANCH}
+./xwords4/android/scripts/arelease.sh
 cp *.apk /tmp
 
 cd $CURDIR