#!/usr/bin/env bash

 #

 # mirror script for Isabelle distribution or website

 ## diagnostics

 PRG=`basename "$0"`

 usage()

 {

   echo

   echo "Usage: $PRG [OPTIONS] DEST"

   echo

   echo "  Options are:"

   echo "    -h    print help message"

   echo "    -n    dry run, don't do anything, just report what would happen"

   echo "    -w    (ignored for backward compatibility)"

   echo "    -d    delete files that are not on the server (BEWARE!)"

   echo

   exit 1

 }

 fail()

 {

   echo "$1" >&2

   exit 2

 }

 ## process command line

 # options

 HELP=""

 ARGS=""

 SRC="isabelle-website"

 while getopts "hnwd" OPT

 do

   case "$OPT" in

     h)

       HELP=true

       ;;

     n)

       ARGS="$ARGS -n"

       ;;

     w)

       echo "option -w ignored"

       ;;

     d)

       ARGS="$ARGS --delete"

       ;;

     \?)

       usage

       ;;

   esac

 done

 shift `expr $OPTIND - 1`

 # help

 if [ -n "$HELP" ]; then

   cat <<EOF

 Mirroring the Isabelle distribution or website

 ==============================================

 The Munich site maintains an rsync server for the Isabelle

 distribution or website.

 The rsync tool is very smart and efficient in mirroring large

 directory hierarchies.  See http://rsync.samba.org/ for more

 information.  The $PRG script provides a simple front-end

 for easy access to the Isabelle distribution.

 The script can be either run in conservative or clean-sweep mode.

 1) Basic mirroring works like this:

   $PRG /foo/bar

 where /foo/bar refers to your local copy of the Isabelle distribution

 (the base directory has to exist already).  This operation is

 conservative in the sense that files are never deleted, thus garbage

 may accumulate over time as our master copy is changed.

 Avoiding garbage in your local copy requires some care.  Rsync

 provides a way to delete all additional local files that are absent in

 the master copy.  This provides an efficient way to purge large

 directory hierarchies, even unwillingly in case that a wrong

 destination is given!

 2a) This will invoke a safe dry-run of clean-sweep mirroring:

   $PRG -dn /foo/bar

 where additions and deletions will be printed without any actual

 changes performed so far.

 2b) Exact mirroring with actual deletion of garbage may be performed

 like this:

   $PRG -d /foo/bar

 After gaining some confidence in the workings of $PRG one

 would usually set up some automatic mirror scheme, e.g. a daily cron

 job run by the 'nobody' user.

 Add -w to the option list in order to mirror the whole Isabelle website

 EOF

   exit 0

 fi

 # arguments

 [ $# -ne 1 ] && { echo "Bad arguments: $*"; usage; }

 DEST="$1"; shift;

 ## main

 exec rsync -va $ARGS "rsync://isabelle.in.tum.de/$SRC" "$DEST/"