First download and extract the latest version of the static FreeBSD binaries provided by the GIMPS project.
mkdir ~/mersenne/ cd ~/mersenne/ ftp ftp://mersenne.org/gimps/sprime235-freebsd.tar.gz tar xzf sprime235-freebsd.tar.gz
Now configure the GIMPS client software. As this is a FreeBSD-binary, you will need to enable FreeBSD kernel emulation with sysctl(8) :
sudo sysctl kern.emul.freebsd=1 ./mprime -m
This will ask you several questions regarding your setup. Answering them here is beyond the scope of this document, please read the accompanying documentation for more information or visit the GIMPS website. Also, please note that this software does not require any special privileges. I usually run it under my own userid, but you could choose to start it as a special, un-priviledged, user.
After configuring the software you're ready to run it. You can either start it by hand, each time you boot your system :
sudo sysctl kern.emul.freebsd=1 ~/mersenne/mprime &
Or you can configure the system to automagically start mprime when it boots by adding a line to rc.local(8) and sysctl.conf(5). As root do :
echo 'sudo -u USERNAME ~/mersenne/mprime &' >> /etc/rc.local echo 'kern.emul.freebsd=1 # enable running FreeBSD binaries' >> /etc/sysctl.conf
Note that this software has some shortcomings :
Despite these shortcoming, I still run it on as many systems as I can. You can see my 'GIMPS ranking' here.