Assume that you have a svn repository with branches, tags and trunk and you only want to run your jenkins-ci runs on the trunk repository.
In that case you want te be sure that commits to branches / tags do not trigger a testrun, so the commit hook needs to take care of that.
Below is an (yet untested) version of an commit hook that should take care of that. It will only trigger jenkins in the case of commits to a trunk subdirectory of a svn repo.
UUID=`svnlook uuid $REPOS`
svnlook dirs-changed -r $REV $REPOS | grep trunk | while read line
--post-data "`svnlook changed -r $REV $REPOS`"
[ $? -ne 0 ] && exit 1
This script does make use of authentication. To remove this, omit the –http- lines of the wget command.