set -e
# parameter: $1: git tag to build
-git clone https://github.com/wagner-tech/kivitendo-erp
-cd kivitendo-erp
-git checkout $1
+# options: -g <alternative repository>
+
+repos="https://github.com/wagner-tech"
+if getopts "g:" opt; then
+ repos=$OPTARG
+ shift 2
+fi
+
+if [ -d kivitendo-erp ]
+then
+ pushd kivitendo-erp >/dev/null
+ branch=$(git rev-parse --abbrev-ref HEAD)
+ git pull origin $branch
+else
+ git clone $repos/kivitendo-erp
+ pushd kivitendo-erp >/dev/null
+fi
+ git checkout $1
+popd >/dev/null