View on
MetaCPAN is shutting down
For details read Perl NOC. After June 25th this page will redirect to
Tim Bunce > perl5.004_04 > perlfaq


Annotate this POD

Source   Latest Release: perl-5.14.4


perlfaq - frequently asked questions about Perl ($Date: 1997/04/24 22:46:06 $)


This document is structured into the following sections:

perlfaq: Structural overview of the FAQ.

This document.

perlfaq1: General Questions About Perl

Very general, high-level information about Perl.

perlfaq2: Obtaining and Learning about Perl

Where to find source and documentation to Perl, support and training, and related matters.

perlfaq3: Programming Tools

Programmer tools and programming support.

perlfaq4: Data Manipulation

Manipulating numbers, dates, strings, arrays, hashes, and miscellaneous data issues.

perlfaq5: Files and Formats

I/O and the "f" issues: filehandles, flushing, formats and footers.

perlfaq6: Regexps

Pattern matching and regular expressions.

perlfaq7: General Perl Language Issues

General Perl language issues that don't clearly fit into any of the other sections.

perlfaq8: System Interaction

Interprocess communication (IPC), control over the user-interface (keyboard, screen and pointing devices).

perlfaq9: Networking

Networking, the Internet, and a few on the web.

Where to get this document

This document is posted regularly to comp.lang.perl.announce and several other related newsgroups. It is available in a variety of formats from CPAN in the /CPAN/doc/FAQs/FAQ/ directory, or on the web at .

How to contribute to this document

You may mail corrections, additions, and suggestions to . Mail sent to the old perlfaq alias will merely cause the FAQ to be sent to you.

What will happen if you mail your Perl programming problems to the authors

Your questions will probably go unread, unless they're suggestions of new questions to add to the FAQ, in which case they should have gone to the instead.

You should have read section 2 of this faq. There you would have learned that comp.lang.perl.misc is the appropriate place to go for free advice. If your question is really important and you require a prompt and correct answer, you should hire a consultant.

Credits ^

When I first began the Perl FAQ in the late 80s, I never realized it would have grown to over a hundred pages, nor that Perl would ever become so popular and widespread. This document could not have been written without the tremendous help provided by Larry Wall and the rest of the Perl Porters.

Author and Copyright Information ^

Copyright (c) 1997 Tom Christiansen and Nathan Torkington. All rights reserved.

Noncommercial Reproduction

Permission is granted to distribute this document, in part or in full, via electronic means or printed copy providing that (1) that all credits and copyright notices be retained, (2) that no charges beyond reproduction be involved, and (3) that a reasonable attempt be made to use the most current version available.

Furthermore, you may include this document in any distribution of the full Perl source or binaries, in its verbatim documentation, or on a complete dump of the CPAN archive, providing that the three stipulations given above continue to be met.

Commercial Reproduction

Requests for all other distribution rights, including the incorporation in part or in full of this text or its code into commercial products such as but not limited to books, magazine articles, or CD-ROMs, must be made to Any commercial use of any portion of this document without prior written authorization by its authors will be subject to appropriate action.


This information is offered in good faith and in the hope that it may be of use, but is not guaranteed to be correct, up to date, or suitable for any particular purpose whatsoever. The authors accept no liability in respect of this information or its use.

Changes ^


Style and whitespace changes from Chip, new question on reading one character at a time from a terminal using POSIX from Tom.


Added to perlfaq2. Style fix to perlfaq3. Added floating point precision, fixed complex number arithmetic, cross-references, caveat for Text::Wrap, alternative answer for initial capitalizing, fixed incorrect regexp, added example of Tie::IxHash to perlfaq4. Added example of passing and storing filehandles, added commify to perlfaq5. Restored variable suicide, and added mass commenting to perlfaq7. Added Net::Telnet, fixed backticks, added reader/writer pair to telnet question, added FindBin, grouped module questions together in perlfaq8. Expanded caveats for the simple URL extractor, gave LWP example, added CGI security question, expanded on the email address answer in perlfaq9.


Added more info to the binary distribution section of perlfaq2. Added Net::Telnet to perlfaq6. Fixed typos in perlfaq8. Added mail sending example to perlfaq9. Added Merlyn's columns to perlfaq2.


Added the DATE to the NAME section, indicating which sections have changed.

Mentioned SIGPIPE and perlipc in the forking open answer in perlfaq8.

Fixed description of a regular expression in perlfaq4.

17/March/97 Version

Various typos fixed throughout.

Added new question on Perl BNF on perlfaq7.

Initial Release: 11/March/97

This is the initial release of version 3 of the FAQ; consequently there have been no changes since its initial release.

syntax highlighting: