poor man's time machine. Works with in cygwin as well as any unix based environment that provides rsync.

timemachine.sh

#!/bin/bash

semaphore() {
  if [ -e $0.pid ]; then
    PID=$(cat $0.pid)
  fi

  if [ $PID ]; then
    echo $PID on file
    PIDr=$( ps -ef | awk '{print $2}' | grep ^$PID$ )
  fi

  if [[ $PIDr && $PID ]]; then
    echo $PIDr in memory
    echo "$0 is running with PID $PID"
    exit 1
  fi

  if [[ !$PIDr || $PID != $$ ]]; then
    echo $$ > $0.pid
  fi
}

semaphore

date=`date "+%Y%m%dT%H%M%S"`
rsync -aH --filter='- *~' --delete --filter='- Backups' --link-dest=$HOME/Backups/current $HOME $HOME/Backups/back-$date
rm $HOME/Backups/current
ln -s back-$date $HOME/Backups/current