diff -r 2bc568573a47 -r 30ed6786d775 src/Pure/System/isabelle_system.scala
--- a/src/Pure/System/isabelle_system.scala	Thu Nov 14 11:49:54 2019 +0100
+++ b/src/Pure/System/isabelle_system.scala	Thu Nov 14 12:42:06 2019 +0100
@@ -152,10 +152,10 @@
   /* permissions */
 
   def chmod(arg: String, path: Path): Unit =
-    bash("chmod " + Bash.string(arg) + " -- " + File.bash_path(path)).check
+    bash("chmod " + Bash.string(arg) + " " + File.bash_path(path)).check
 
   def chown(arg: String, path: Path): Unit =
-    bash("chown " + Bash.string(arg) + " -- " + File.bash_path(path)).check
+    bash("chown " + Bash.string(arg) + " " + File.bash_path(path)).check
 
 
   /* directories */