Sometimes when testing a Nagios Plugin on the command line, it’s useful to know the exit code.
You can always use echo $?, but that becomes tedious if you have to type it often.
Additionally you have to remember what the exit codes mean.
The following snippet adds a prompt that changes colour according to the exit code; 0 is green, 1 is yellow, 2 is red and 3 is grey. This makes it easy to see at a glance what the exit code was.
Add the following to a file e.g. debug.sh
export colormap=([0]=32 [1]=33 [2]=31 [3]=37)
export PS1='\[\e[${colormap[$?]}m\]\u@\h:\w\$\[\e[30m\] '
Then source it in .bashrc or on the command line with
source debug.sh
and enjoy.
nagios@localhost:~$ ./check_plugin 192.168.0.1
OK - 1824 bytes in 0.002 seconds
nagios@localhost:~$ ./check_plugin 192.168.0.2
Unable to open TCP socket
nagios@localhost:~$
And again users of the zsh are in advantage. In the same situation they do what? Correct: They do nothing!
Zsh by default prints the return code of each command – if not zero – in front of the next prompt.
And only at the *next* prompt, not on every following…