How to upgrade Nagios core 3.5.0 to 4.0.8 version?

  Download nagios-4.0.8.tar.gz from http://www.nagios.org/download 

  Untar the source code:

# tar zxvf nagios-4.0.8.tar.gz

# cd nagios-4.0.8

  Compile the new source code:

nagios-4.0.8]# ./configure --with-command-group=nagcmd

nagios-4.0.8]# make all

nagios-4.0.8]# make install

  

  Verify the Nagios configuration for errors:

nagios-4.0.8]# /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

Nagios Core 4.0.8

Copyright (c) 2009-present Nagios Core Development Team and Community Contributors

Copyright (c) 1999-2009 Ethan Galstad

Last Modified: 08-12-2014

License: GPL

Website: http://www.nagios.org

Reading configuration data...

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Running pre-flight check on configuration data...

Checking objects...

        Checked 1231 services.

        Checked 221 hosts.

        Checked 34 host groups.

        Checked 2 service groups.

        Checked 28 contacts.

        Checked 27 contact groups.

        Checked 127 commands.

        Checked 7 time periods.

        Checked 0 host escalations.

        Checked 0 service escalations.

Checking for circular paths...

        Checked 221 hosts

        Checked 0 service dependencies

        Checked 172 host dependencies

        Checked 7 timeperiods

Checking global event handlers...

Checking obsessive compulsive processor commands...

Checking misc settings...

Total Warnings: 0

Total Errors:   0

  Start Nagios service # service nagios restart

  Now check Nagios GUI http://<Nagios server IP>/nagios and observe the new version.