src/Pure/Admin/build_release.scala

             Isabelle_System.rm_tree(linux_app)
 
             val archive_name = isabelle_name + "_linux.tar.xz"
             progress.echo("Packaging " + archive_name + " ...")
             execute_tar(tmp_dir,
-              "-cf- " + Bash.string(isabelle_name) +
-              " | xz > " + File.bash_path(release.dist_dir + Path.explode(archive_name)))
+              "-cJf " + File.bash_path(release.dist_dir + Path.explode(archive_name)) + " " +
+              Bash.string(isabelle_name))
 
 
           case Platform.Family.macos =>
             File.write(isabelle_target + jedit_props,
               File.read(isabelle_target + jedit_props)

             // application archive
 
             val archive_name = isabelle_name + "_macos.tar.xz"
             progress.echo("Packaging " + archive_name + " ...")
             execute_tar(tmp_dir,
-              "-cf- " + File.bash_path(isabelle_app) +
-              " | xz > " + File.bash_path(release.dist_dir + Path.explode(archive_name)))
+              "-cJf " + File.bash_path(release.dist_dir + Path.explode(archive_name)) + " " +
+              File.bash_path(isabelle_app))
 
 
           case Platform.Family.windows =>
             File.write(isabelle_target + jedit_props,
               File.read(isabelle_target + jedit_props)