Add a system user

Use below command if you need to add a system user account (for example to run svnserve as daemon)

 sudo adduser --system --no-create-home --home /nonexistent --shell /usr/sbin/nologin --disabled-password --disabled-login svnowner  

and run it as

 sudo -u svnowner svnserve -d -r /opt/svn/repos/