diff -r 6cfec8029831 -r 3199c08e6413 src/Pure/System/linux.scala
--- a/src/Pure/System/linux.scala	Thu Nov 14 11:35:02 2019 +0100
+++ b/src/Pure/System/linux.scala	Thu Nov 14 11:36:14 2019 +0100
@@ -133,7 +133,7 @@
 
     val service_file = Path.explode("/lib/systemd/system") + Path.basic(name).ext("service")
     File.write(service_file, spec)
-    Isabelle_System.chmod("0644", service_file)
+    Isabelle_System.chmod("644", service_file)
 
     service_enable(name)
     service_restart(name)