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Devel::Autoflush(3pm) User Contributed Perl Documentation Devel::Autoflush(3pm)


Devel::Autoflush - Set autoflush from the command line


version 0.06


 perl -MDevel::Autoflush Makefile.PL


This module is a hack to set autoflush for STDOUT and STDERR from the command line or from "PERL5OPT" for code that needs it but doesn't have it.

This often happens when prompting:

  print "Guess a number: ";
  my $n = <STDIN>;

As long as the output is going to a terminal, the prompt is flushed when STDIN is read. However, if the output is being piped, the print statement will not automatically be flushed, no prompt will be seen and the program will silently appear to hang while waiting for input. This might happen with 'tee':

  $ perl | tee capture.out

Use Devel::Autoflush to work around this:

  $ perl -MDevel::Autoflush | tee capture.out

Or set it in "PERL5OPT":

  $ export PERL5OPT=-MDevel::Autoflush
  $ perl | tee capture.out


CPANPLUS::Internals::Utils::Autoflush -- same idea but STDOUT only and

only available as part of the full CPANPLUS distribution


Bugs / Feature Requests

Please report any bugs or feature requests through the issue tracker at <>. You will be notified automatically of any progress on your issue.

Source Code

This is open source software. The code repository is available for public review and contribution under the terms of the license.


  git clone


David Golden <>


This software is Copyright (c) 2014 by David Golden.

This is free software, licensed under:

  The Apache License, Version 2.0, January 2004
2021-01-05 perl v5.32.0