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Perl::Critic::Policy::InputOutput::ProhibitBacktickOperaUser(Contributed Perl DocPerl::Critic::Policy::InputOutput::ProhibitBacktickOperators(3pm)

NAME
Perl::Critic::Policy::InputOutput::ProhibitBacktickOperators - Discourage stuff like "@files = `ls $directory`". AFFILIATION
This Policy is part of the core Perl::Critic distribution. DESCRIPTION
Backticks are super-convenient, especially for CGI programs, but I find that they make a lot of noise by filling up STDERR with messages when they fail. I think its better to use IPC::Open3 to trap all the output and let the application decide what to do with it. use IPC::Open3 'open3'; $SIG{CHLD} = 'IGNORE'; @output = `some_command`; #not ok my ($writer, $reader, $err); open3($writer, $reader, $err, 'some_command'); #ok; @output = <$reader>; #Output here @errors = <$err>; #Errors here, instead of the console CONFIGURATION
Alternatively, if you do want to use backticks, you can restrict checks to void contexts by adding the following to your .perlcriticrc file: [InputOutput::ProhibitBacktickOperators] only_in_void_context = 1 The purpose of backticks is to capture the output of an external command. Use of them in a void context is likely a bug. If the output isn't actually required, "system()" should be used. Otherwise assign the result to a variable. `some_command`; #not ok $output = `some_command`; #ok @output = `some_command`; #ok NOTES
This policy also prohibits the generalized form of backticks seen as "qx{}". See perlipc for more discussion on using "wait()" instead of "$SIG{CHLD} = 'IGNORE'". You might consider using the "capture()" function from the IPC::System::Simple module for a safer way of doing what backticks do, especially on Windows. The module also has a safe wrapper around "system()". AUTHOR
Jeffrey Ryan Thalhammer <jeff@imaginative-software.com> COPYRIGHT
Copyright (c) 2005-2011 Imaginative Software Systems. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The full text of this license can be found in the LICENSE file included with this module. perl v5.14.2 2012-06-07 Perl::Critic::Policy::InputOutput::ProhibitBacktickOperators(3pm)

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