diff -r 1222c010bff7 -r 9ed87c82cbe7 src/Pure/Admin/build_cygwin.scala
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Pure/Admin/build_cygwin.scala	Tue Feb 28 19:50:08 2017 +0100
@@ -0,0 +1,89 @@
+/*  Title:      Pure/Admin/build_cygwin.scala
+    Author:     Makarius
+
+Produce pre-canned Cygwin distribution for Isabelle.
+*/
+
+package isabelle
+
+
+object Build_Cygwin
+{
+  val default_mirror: String = "http://isabelle.in.tum.de/cygwin_2016-1"
+
+  val packages: List[String] =
+    List("curl", "nano", "perl", "perl-libwww-perl", "rlwrap", "unzip")
+
+  def build_cygwin(progress: Progress,
+    mirror: String = default_mirror,
+    more_packages: List[String] = Nil)
+  {
+    require(Platform.is_windows)
+
+    Isabelle_System.with_tmp_dir("cygwin")(tmp_dir =>
+      {
+        val cygwin = tmp_dir + Path.explode("cygwin")
+        val cygwin_etc = cygwin + Path.explode("etc")
+        val cygwin_isabelle = cygwin + Path.explode("isabelle")
+        Isabelle_System.mkdirs(cygwin_isabelle)
+
+        val cygwin_exe_name = mirror + "/setup-x86.exe"
+        val cygwin_exe = cygwin_isabelle + Path.explode("cygwin.exe")
+        Bytes.write(cygwin_exe,
+          try { Bytes.read(Url(cygwin_exe_name)) }
+          catch { case ERROR(_) => error("Failed to download " + quote(cygwin_exe_name)) })
+
+        Isabelle_System.bash(
+          "chmod +x " + File.bash_path(cygwin_exe) + " && " +
+          File.bash_path(cygwin_exe) + " -h </dev/null >/dev/null").check
+
+        val res =
+          progress.bash(
+            File.bash_path(cygwin_exe) + " --site " + Bash.string(mirror) + " --no-verify" +
+              " --local-package-dir 'C:\\temp'" +
+              " --root " + Bash.string(File.platform_path(cygwin)) +
+              " --packages " + quote((packages ::: more_packages).mkString(",")) +
+              " --no-shortcuts --no-startmenu --no-desktop --quiet-mode",
+            echo = true)
+        if (!res.ok || !cygwin_etc.is_dir) error("Failed")
+
+        for (name <- List("hosts", "protocols", "services", "networks", "passwd", "group"))
+          (cygwin_etc + Path.explode(name)).file.delete
+
+        (cygwin + Path.explode("Cygwin.bat")).file.delete
+
+        val archive = "cygwin-" + Date.Format("uuuuMMdd")(Date.now()) + ".tar.gz"
+        Isabelle_System.gnutar("-C " + File.bash_path(tmp_dir) +
+          " -czf " + Bash.string(archive) + " cygwin").check
+      })
+  }
+
+
+  /* Isabelle tool wrapper */
+
+  val isabelle_tool =
+    Isabelle_Tool("build_cygwin", "produce pre-canned Cygwin distribution for Isabelle", args =>
+    {
+      var mirror = default_mirror
+      var more_packages: List[String] = Nil
+
+      val getopts =
+        Getopts("""
+Usage: isabelle build_cygwin [OPTIONS]
+
+  Options are:
+    -R MIRROR    Cygwin mirror site (default """ + quote(default_mirror) + """)
+    -p NAME      additional Cygwin package
+
+  Produce pre-canned Cygwin distribution for Isabelle: this requires
+  Windows administrator mode.
+""",
+          "R:" -> (arg => mirror = arg),
+          "p:" -> (arg => more_packages ::= arg))
+
+      val more_args = getopts(args)
+      if (more_args.nonEmpty) getopts.usage()
+
+      build_cygwin(new Console_Progress(), mirror = mirror, more_packages = more_packages)
+    }, admin = true)
+}