I am new to Nagios configuration. We have Nagios installed. I need to make the output length bigger. I modified MAX_PLUGINOUTPUT_LENGTH in objects.h header file. I know I have to recompile nagios. How do I recompile it without impact existing configuration? Thanks a lot!
make a copy of your config files, follow instructions for configure, make all, stop nagios, make install, start nagios.
your config shouldn’t have changed.
Well, guess no easier ways. I hoped just one command line to recompile. 
Thanks a lot! Do you mean to restart the service. Yes, I did that. It didn’t pick up the changes.
you could probably try to make only the single file… but if you don’t know why did you change a source file?
Are you sure about the implications of your change?
Are there other places where the variable is used?
Are there checks for the data consistency or are you risking some sort of overflow somewhere else in the program? 
I know if you want to show more output in nagios, it is the place to modify the size. I can’t make single file. not sure who are using this header file. Thank you for all the headsup!