Capturing output of perl script called through pipe from another perl script

Question

Here is the code snippet of main script. The main script is calling populate_details script through pipe. Sending 2 arrays inv1 and inv2 as input.

 *my $fh = FileHandle->new('| ./populate_details') 
 print $fh Data::Dumper->Dump([\@inv1], [qw(inv1)]);
 print $fh Data::Dumper->Dump([\@inv2], [qw(inv2)]);*

The question is , how to capture the return code and return value from populate_details script ? For example, the populate_details script is sending as hash of return values.

Could you Please help ?

Tip: No point in using FileHandle. You can use open(my $fh, '| ./populate_details') — ikegami
– ikegami, Commented Oct 3, 2019 at 19:18
For sending hashes between processes you could use JSON, see for example JSON::XS — Håkon Hægland
– Håkon Hægland, Commented Oct 3, 2019 at 20:29
Thanks ! Could you please give me an example plz , on how to get the hash from the child script ? — vamsi krishna
– vamsi krishna, Commented Oct 3, 2019 at 22:24
Scripts do not return things. Check out perldoc perlmod for how to set up Perl code so it can be called from other Perl code. — Grinnz
– Grinnz, Commented Oct 4, 2019 at 17:26

mob · Accepted Answer · 2019-10-03 19:08:24Z

1

To retrieve the exit status, close the filehandle and check $?

If the filehandle came from a piped open, close returns false if one of the other syscalls involved fails or if its program exits with non-zero status. If the only problem was that the program exited non-zero, $! will be set to 0. Closing a pipe also waits for the process executing on the pipe to exit--in case you wish to look at the output of the pipe afterwards--and implicitly puts the exit status value of that command into $? and ${^CHILD_ERROR_NATIVE}.

answered Oct 3, 2019 at 19:08

mob

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2 Comments

vamsi krishna Over a year ago

Thanks !! If i need to capture the return hash sent by the child script, how to capture it ?

mob Over a year ago

Check out IPC::Open2

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