Perl::...rators(3pm)

💅 Perl::...rators(3pm) 💅

✨ User Contributed Perl Documentation, but make it group-chat ✨

🌸 NAME 🌸

bestie, this policy is named Perl::Critic::Policy::InputOutput::ProhibitBacktickOperators, and it's here to discourage stuff like this little menace:

@files = `ls $directory`

periodt 💅

🫶 AFFILIATION 🫶

This Policy is part of the core Perl::Critic distribution. slay.

✨ DESCRIPTION ✨

okay so backticks are super-convenient, especially for CGI programs, but they lowkey make a lot of noise 😭 — when they fail, they fill up STDERR with messages. The author thinks it's 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 actually 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.

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bye bestie 🫶 this page was brought to you by perl v5.42.0, dated 2024-10-23 ✨💖