Hello Brothers,

I'm quite new to doing IPC work in Perl, and I'm having a devil of a time handling errors. For example, I do this, using IPC::Open3: 

my $pid = open3( $wtr, $rdr, $err, $httpd, '-v' );
my ($version, $builtondate) = <$rdr>;

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and that works just fine--when the binary is correctly specified in $httpd. If I move the binary out of the way for testing so that the call will fail, I get errors spewed to my terminal about undefined variables and such, which I would expect.

So I would like to trap the failure. What I understood from the cpan page for IPC::Open3 is that errors would be written to the $err filehand however if I do this: 

print readline $err;

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when I've moved the httpd binary out of the way, I get this error from my script: 
Use of uninitialized value in <HANDLE> at ./test.pl line 248.
readline() on unopened filehandle at ./test.pl line 248.

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Shouldn't the failure to execute httpd have been printed to that $err filehandle so that I can trap it? Or is that just for errors from the executed process itself?

I've tried all kinds of gymnastics using backtick shell commands, pipes, etc. but haven't found a way to trap the failure to execute.

Any input would be greatly appreciated!

In reply to Error handling in Inter Process Communication by rastoboy

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