Re: Reading return value from C program

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 $?

Comment on Re: Reading return value from C program Select or Download Code

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Re^2: Reading return value from C program by ikegami (Patriarch) on Mar 15, 2007 at 18:00 UTC
`fork` sets `$!`, not `$?`.	[reply] [d/l] [select]
Re^3: Reading return value from C program by Anno (Deacon) on Mar 15, 2007 at 18:20 UTC
agianni's code wouldn't make sense after a `fork()`, that's true. It would make sense after a `waitpid`. Maybe that was the tacit assumption. It would have been better made explicit. Anno	[reply] [d/l] [select]
Re^4: Reading return value from C program by ikegami (Patriarch) on Mar 15, 2007 at 19:08 UTC
Even after `waitpid`, `$?` doesn't indicate whether the child was launched successfully or not. `$?` indicates whether the child ended successfully.	[reply] [d/l] [select]
Re^5: Reading return value from C program by agianni (Hermit) on Mar 15, 2007 at 20:40 UTC