When you work with at least two computers on the same project on a daily basis you might have a problem. You need to get changed files from host A to host B and vice versa. The problem getting bigger when you work in addition on different operation systems or use more than two hosts. On UNIX/Linux the preferred tool for such a task is Rsync. Unfortunately Rsync synchronize only in one direction, it doesn’t work very well when more than two hosts are involved (and it isn’t really comfortable to set up on Windows) and can’t use a secure communication channel. Another approach is to check-in changed source files into a version control system, like CVS. On host A you check it in and on host B you check it out afterwards. But this means you always need a more or less stable variant of your code, so that other developer can, at least compile, or much better use it. That is not always the case (especially when you leave the office at 11:00 p.m.) and it also doesn’t cover files which aren’t handled by a version control system. Luckily there is a solution for all the problems mentioned which is called Unison. So here comes the second post in the ToolTips series, which covers an easy and portable way for file synchronization.