diff --git a/images/build_images.sh b/images/build_images.sh
index c60c149..7ef26f7 100755
--- a/images/build_images.sh
+++ b/images/build_images.sh
@@ -1,29 +1,45 @@
 #!/usr/bin/env bash
 
 builddate=$(date +%Y%m%d)
 buildtime=$(date +%H%M%S)
 builddatetime="${builddate}-${buildtime}"
 
 username=$(docker info | grep Username | awk '{print $2}')
+options=$(getopt -l "write-env-file:" -o "" -- "$@") || exit 1
 
 for img in base web replayer test; do
     docker build \
            --build-arg SWH_VER=${builddatetime} \
            --build-arg debianversion=buster \
            --tag softwareheritage/${img}:${builddatetime} \
            --target swh-${img} \
            .
     docker tag softwareheritage/${img}:${builddatetime} softwareheritage/${img}:${builddate}
     docker tag softwareheritage/${img}:${builddate} softwareheritage/${img}:latest
   if [[ -n "${username}" ]] && [[ "${PUBLISH:=no}" = "yes" ]]; then
       echo "Publishing image softwareheritage:${img}-${builddate} on docker hub"
       docker push softwareheritage/${img}:${builddatetime}
       docker push softwareheritage/${img}:${builddate}
       docker push softwareheritage/${img}:latest
   fi
 done
 
 #docker tag softwareheritage:base-${builddate} softwareheritage:latest
 
+eval set -- "$options"
+while true; do
+    case "$1" in
+        --write-env-file)
+            shift
+            echo "SWH_IMAGE_TAG=${builddatetime}" > "$1"
+            ;;
+        --)
+            shift
+            break
+            ;;
+    esac
+    shift
+done
+
 echo "Done creating images. You may want to use"
 echo "export SWH_IMAGE_TAG=${builddatetime}"