====== Nagios_upgrade_issue ======

Nagios would not start after upgrading from sarge to etch.

Again, the problem was that old configs were kept, rather than installing the new version. The problem was:
 server:~# /etc/init.d/nagios start
 Starting nagios monitoring daemon: nagios
 Nagios 1.4
 Copyright (c) 1999-2006 Ethan Galstad (nagios@nagios.org)
 Last Modified: 05-03-2006
 License: GPL
 Reading configuration data...
 Error: Command 'check-fast-alive' has already been defined
 Error: Could not register command (config file '/etc/nagios-plugins/config/ping.cfg', line 37)
 ***> One or more problems was encountered while processing the config files...
     Check your configuration file(s) to ensure that they contain valid
     directives and data defintions.  If you are upgrading from a previous
     version of Nagios, you should be aware that some variables/definitions
     may have been removed or modified in this version.  Make sure to read
     the HTML documentation on the main and host config files, as well as the
     'Whats New' section to find out what has changed.
 errors in config!
  failed!

Solution:
In /etc/nagios-plugins/config/ there was ping.cfg **and** ping.cfg.ucf-dist. The latter was the most recent config. The difference between the two was the extra piece on check-fast-alive. It had to be removed from ping.cfg and then nagios started fine. 

===== ping.cfg: =====
 # 'check_ping' command definition
 define command{
        command_name    check_ping
        command_line    /usr/lib/nagios/plugins/check_ping -H $HOSTADDRESS$ -w $ARG1$ -c $ARG2$
        }
 
 
 # 'check-host-alive' command definition
 define command{
        command_name    check-host-alive
        command_line    /usr/lib/nagios/plugins/check_ping -H $HOSTADDRESS$ -w 5000,100% -c 5000,100% -p 1
        }
 
 
 # 'check-printer-alive' command definition
 define command{
        command_name    check-printer-alive
        command_line    /usr/lib/nagios/plugins/check_ping -H $HOSTADDRESS$ -w 5000,100% -c 5000,100% -p 1
        }
 
 
 # 'check-switch-alive' command definition
 define command{
        command_name    check-switch-alive
        command_line    /usr/lib/nagios/plugins/check_ping $HOSTADDRESS$ -w 5000,100% -c 5000,100% -p 1
        }
 
 
 # 'check-router-alive' command definition
 define command{
        command_name    check-router-alive
        command_line    /usr/lib/nagios/plugins/check_ping -H $HOSTADDRESS$ -w 5000,100% -c 5000,100% -p 1
        }