Do not create user and group if they already exist

scripts/bin/container-foreground-cmd

@@ -6,22 +6,24 @@ set -eu
 _IFS=${IFS}; IFS=,
 for gid in ${UNPRIVILEGED_USER_GROUPS?}; do
 	if ! getent group "${gid:?}" >/dev/null 2>&1; then
-		groupadd -g "${gid:?}" "g_${gid:?}"
+		groupadd --gid "${gid:?}" "g_${gid:?}"
 	fi
 done
 IFS=$_IFS
 
 # Create unprivileged user and group
-groupadd \
-	--gid "${UNPRIVILEGED_USER_GID:?}" \
-	"${UNPRIVILEGED_USER_NAME:?}"
-useradd \
-	--uid "${UNPRIVILEGED_USER_UID:?}" \
-	--gid "${UNPRIVILEGED_USER_GID:?}" \
-	--groups "${UNPRIVILEGED_USER_GROUPS?}" \
-	--shell "${UNPRIVILEGED_USER_SHELL:?}" \
-	--create-home \
-	"${UNPRIVILEGED_USER_NAME:?}"
+if ! getent group "${UNPRIVILEGED_USER_GID:?}" >/dev/null 2>&1; then
+	groupadd --gid "${UNPRIVILEGED_USER_GID:?}" "${UNPRIVILEGED_USER_NAME:?}"
+fi
+if ! getent passwd "${UNPRIVILEGED_USER_UID:?}" >/dev/null 2>&1; then
+	useradd \
+		--uid "${UNPRIVILEGED_USER_UID:?}" \
+		--gid "${UNPRIVILEGED_USER_GID:?}" \
+		--groups "${UNPRIVILEGED_USER_GROUPS?}" \
+		--shell "${UNPRIVILEGED_USER_SHELL:?}" \
+		--create-home \
+		"${UNPRIVILEGED_USER_NAME:?}"
+fi
 
 # Copy /etc/skel/ to unprivileged user home if empty
 UNPRIVILEGED_USER_HOME=$(getent passwd "${UNPRIVILEGED_USER_NAME:?}" | cut -d: -f6)