another try

docker/start-notebook.sh

@@ -2,4 +2,34 @@
 # Shim to emit warning and call start-notebook.py
 echo "WARNING: Use start-notebook.py instead"
 
-exec /usr/local/bin/start-notebook.py "$@"
+if id jovyan &> /dev/null; then
+        if ! usermod --home "/home/${NB_USER}" --login "${NB_USER}" jovyan 2>&1 | grep "no changes" > /dev/null; then
+            echo "Updated the jovyan user:"
+            echo "- username: jovyan       -> ${NB_USER}"
+            echo "- home dir: /home/jovyan -> /home/${NB_USER}"
+        fi
+elif ! id -u "${NB_USER}" &> /dev/null; then
+        echo "ERROR: Neither the jovyan user nor '${NB_USER}' exists. This could be the result of stopping and starting, the container with a different NB_USER environment variable."
+        exit 1
+fi
+# Ensure the desired user (NB_USER) gets its desired user id (NB_UID) and is
+# a member of the desired group (NB_GROUP, NB_GID)
+if [ "${NB_UID}" != "$(id -u "${NB_USER}")" ] || [ "${NB_GID}" != "$(id -g "${NB_USER}")" ]; then
+        echo "Update ${NB_USER}'s UID:GID to ${NB_UID}:${NB_GID}"
+        # Ensure the desired group's existence
+        if [ "${NB_GID}" != "$(id -g "${NB_USER}")" ]; then
+            groupadd --force --gid "${NB_GID}" --non-unique "${NB_GROUP:-${NB_USER}}"
+        fi
+        # Recreate the desired user as we want it
+        userdel "${NB_USER}"
+        useradd --no-log-init --home "/home/${NB_USER}" --shell /bin/bash --uid "${NB_UID}" --gid "${NB_GID}" --groups 100 "${NB_USER}"
+fi
+
+
+# if root change user to jovyan
+if [ "$EUID" -eq 0 ]; then
+    echo "WARNING: Running as root. Use start-notebook.py to run as ${NB_USER} user"
+    exec su ${NB_USER} -c "exec /usr/local/bin/start-notebook.py $@"
+else
+    exec /usr/local/bin/start-notebook.py "$@"
+fi