The first release candidate for Nagios Core 4.1.0 has been released

Maybe you want to upgrade version 4.0.8 to 4.1.0rc1
Firstly;

su -l nagios

Removed the following old HTML files that were used by the web frontend. They have been replaced by PHP equivalents.

rm /usr/local/nagios/share/{main,side,index}.html

Download the source code tarball of the latest version of Nagios (visit http://www.nagios.org/download/ for the link to the latest version).

wget http://osdn.dl.sourceforge.net/sourceforge/nagios/nagios-x.y.z.tar.gz

Extract the Nagios source code tarball.

tar xzf nagios-x.y.z.tar.gz

cd nagios

Run the Nagios configure script, passing the name of the group used to control external command file permissions like so:

./configure --with-command-group=nagcmd

Compile the Nagios source code.

make all

Install updated binaries, documentation, and web web interface. Your existing configuration files will not be overwritten by this step.

make install

Verify your configuration files. Correct any errors shown here before proceeding with the next step.

/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

Restart Nagios. Debian/Ubuntu users should use /etc/init.d/nagios restart.

/sbin/service nagios restart

That’s it – you’re done!