I use $ Rev: $ in the file to have a version number, the problem is that the file does not change much, so the number is not updated automatically. Any help on how to do this?
$ Rev $ will not work as you expect.
If you use a disruptive command line operation, you are svnversion , which displays the latest version.
From tortoisesvn, http://tortoisesvn.net/docs/release/TortoiseSVN_en/tsvn-subwcrev.html
In any case, you should update your compilation script so that it automatically combines the latest revision number.
If you use this for the build / version number in a file, look in the svnrev or WCSubRev tools to create the information you need.