Update Dockerfile

Author: madalinignisca

Dockerfile

@@ -21,8 +21,10 @@ ADD unminimize /tmp/unminimize
 RUN chmod 700 /tmp/unminimize \
     && /tmp/unminimize
 
-RUN [ -n CREATE_USER ] && groupadd --gid ${USER_GID} ${USERNAME} \
+RUN if [ -n CREATE_USER ]; then \
+    groupadd --gid ${USER_GID} ${USERNAME} \
     && useradd --create-home --shell /bin/bash --uid ${USER_UID} --gid ${USER_GID} ${USERNAME}
+    fi
 
 RUN apt-get update \
     && apt-get upgrade -y \