Hi, first thanks for reply.
Second, I wrote the code wrong here, putted the if statement in wrong place(it's not original code, as the original has bit more stuff, but it's not relevant for this problem).
I have fixed the code in the first post, but in case of that you have seen it would print nothing...
I do think that the problem is some way related to the linux machine, but I don't understand how, as the script running on windows machine and just return the output to linux via nrpe...