For me,

exceptRule= '$file =~ \'(/\.)|(^\.)\''

seems to work - but it doesn't do what you want.

Remember, $file contains the relative path plus the filename. So simply using ^\. will only match, if the files are on the top level directory.
Also, with exceptRule you can exclude files but not directories! So the pattern above only excludes singular files starting with a dot.


If you want to exclude directories, you have to use exceptDirs.
The wildcards (not pattern) you need to exclude, depends on the relative path in your backup directory.
Example: If your backupDir is '/', and you want to exclude all dot files in your home directories, use
exceptDirs = //.*
This will e.g. match /home/bob/.something


Btw,
I'm using:
exceptRule= '$file =~ m#/\.thumbnails/#' or
    '$file =~ m#/te?mp/#i' or
    '$file =~ m#cache/#i' or
    '&::MARK_DIR_REC($file, ".dontBackup")'
This stores the important hidden files but not the garbage in it. Also, I can tag a directory with ".dontBackup" .


Hope this helps.