You might find this thread insightful.

As for !$?, $? is a Perl special variable for child error. So if your script forks a child process and there is an error, this will contain that error. ! is the not operator. I'm guessing you're seeing something like: 

if ( !$? ){
   # do the stuff you do after a forked process completes sucessfully
}

[download]

But that would be much easier to read as: 

use English qw(no_match_vars);

if ( not $CHILD_ERROR ){
   # do the stuff you do after a forked process completes sucessfully
}

[download]

Updated comments to reflect meaning of $?

In reply to Re: Reading return value from C program by agianni
in thread Reading return value from C program by Anonymous Monk

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