NAME
Perl::Critic::Policy::ProhibitPipeOpen - Don't let a pipe open be the quiet way to shell out.
VERSION
version 1.000
Perl::Critic::Policy::ProhibitPipeOpen
Perl::Critic::Policy::logicLAB::ProhibitShellDispatch flags system, exec, qx and backticks, which is every obvious way to run an external command -- and not the pipe open, which does the same thing and reads the command's output besides:
open( my $fh, '-|', $bin, '--version' ); # not flagged by that policy
my $version = qx{$bin --version}; # flaggedHaving one of those be quietly acceptable turns the linter into an argument for writing the shell-out in whichever spelling it happens not to look at, rather than a decision somebody made. This policy closes that off, so that every way of starting a process needs the same explicit ## no critic and the comment that ought to go with it.
It is not that a pipe open is worse. In the list form it is the better of the two -- no shell, so no quoting to get wrong. It is that either one should be on the record.
Modelled on Perl::Critic::Policy::InputOutput::ProhibitTwoArgOpen, which has the inverse job: it exempts the fork handles this policy exists to find.
PROHIBITED
open( my $fh, '-|', 'ls', '-l' ); # three-arg, read from a command
open( my $fh, '|-', 'mail', $to ); # three-arg, write to a command
open( my $fh, '-|' ); # two-arg fork
open( FH, 'ls -l |' ); # two-arg, the old spelling
open( FH, '| mail bob' );ALLOWED
Ordinary file opens, which is every other thing open does:
open( my $fh, '<', $path );
open( my $fh, '>>', $path );
open( my $fh, '<', \$scalar );CONFIGURATION
This policy is not configurable except for the standard options.
CAVEATS
The mode has to be a literal for this to see it. A pipe open assembled at runtime, open( $fh, $mode, $cmd ) with $mode computed, goes unnoticed: the policy reads source, not intent.
METHODS
supported_parameters
None.
default_severity
SEVERITY_HIGHEST
default_themes
security, performance
applies_to
PPI::Token::Word
violates
Standard Perl::Critic::Policy interface. Returns a violation for an open whose mode says to spawn a process, and nothing for one that opens a file.
BUGS
Please report any bugs or feature requests on the bugtracker website https://github.com/teodesian/perl-critic-policy-prohibitpipeopen/issues
When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.
AUTHORS
Current Maintainers:
George S. Baugh <teodesian@gmail.com>
CONTRIBUTOR
George Baugh <andy@troglodyne.net>
COPYRIGHT AND LICENSE
Copyright (c) 2026 Troglodyne LLC
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.