=head1 NAME
-perlfaq3 - Programming Tools ($Revision: 1.19 $)
+perlfaq3 - Programming Tools ($Revision: 1.27 $, $Date: 1998/07/05 15:07:20 $)
=head1 DESCRIPTION
someone has already written a module that can solve your problem.
Have you read the appropriate man pages? Here's a brief index:
+ Basics perldata, perlvar, perlsyn, perlop, perlsub
+ Execution perlrun, perldebug
+ Functions perlfunc
Objects perlref, perlmod, perlobj, perltie
Data Structures perlref, perllol, perldsc
- Modules perlmod, perlsub
- Regexps perlre, perlfunc, perlop
+ Modules perlmod, perlmodlib, perlsub
+ Regexps perlre, perlfunc, perlop, perllocale
Moving to perl5 perltrap, perl
Linking w/C perlxstut, perlxs, perlcall, perlguts, perlembed
Various http://www.perl.com/CPAN/doc/FMTEYEWTK/index.html
=head2 How do I cross-reference my Perl programs?
The B::Xref module, shipped with the new, alpha-release Perl compiler
-(not the general distribution), can be used to generate
-cross-reference reports for Perl programs.
+(not the general distribution prior to the 5.005 release), can be used
+to generate cross-reference reports for Perl programs.
- perl -MO=Xref[,OPTIONS] foo.pl
+ perl -MO=Xref[,OPTIONS] scriptname.plx
=head2 Is there a pretty-printer (formatter) for Perl?
(but not all) code, and even less programmable editors can provide
significant assistance.
-If you are using to using vgrind program for printing out nice code to
+If you are used to using vgrind program for printing out nice code to
a laser printer, you can take a stab at this using
http://www.perl.com/CPAN/doc/misc/tips/working.vgrind.entry, but the
results are not particularly satisfying for sophisticated code.
=head2 Where can I get Perl macros for vi?
For a complete version of Tom Christiansen's vi configuration file,
-see ftp://ftp.perl.com/pub/vi/toms.exrc, the standard benchmark file
-for vi emulators. This runs best with nvi, the current version of vi
-out of Berkeley, which incidentally can be built with an embedded Perl
-interpreter -- see http://www.perl.com/CPAN/src/misc .
+see http://www.perl.com/CPAN/authors/Tom_Christiansen/scripts/toms.exrc,
+the standard benchmark file for vi emulators. This runs best with nvi,
+the current version of vi out of Berkeley, which incidentally can be built
+with an embedded Perl interpreter -- see http://www.perl.com/CPAN/src/misc.
=head2 Where can I get perl-mode for emacs?
=head2 How can I use curses with Perl?
The Curses module from CPAN provides a dynamically loadable object
-module interface to a curses library.
+module interface to a curses library. A small demo can be found at the
+directory http://www.perl.com/CPAN/authors/Tom_Christiansen/scripts/rep;
+this program repeats a command and updates the screen as needed, rendering
+B<rep ps axu> similar to B<top>.
=head2 How can I use X or Tk with Perl?
-Tk is a completely Perl-based, object-oriented interface to the Tk
-toolkit that doesn't force you to use Tcl just to get at Tk. Sx is an
-interface to the Athena Widget set. Both are available from CPAN.
+Tk is a completely Perl-based, object-oriented interface to the Tk toolkit
+that doesn't force you to use Tcl just to get at Tk. Sx is an interface
+to the Athena Widget set. Both are available from CPAN. See the
+directory http://www.perl.com/CPAN/modules/by-category/08_User_Interfaces/
=head2 How can I generate simple menus without using CGI or Tk?
The http://www.perl.com/CPAN/authors/id/SKUNZ/perlmenu.v4.0.tar.gz
module, which is curses-based, can help with this.
-=head2 Can I dynamically load C routines into Perl?
-
-If your system architecture supports it, then the standard perl
-on your system should also provide you with this via the
-DynaLoader module. Read L<perlxstut> for details.
-
=head2 What is undump?
See the next questions.
less memory than equivalent Perl modules.
Another thing to try is learning whether your Perl was compiled with
-the system malloc or with Perl's built-in malloc. Whichever one it
+the system malloc or with Perl's builtin malloc. Whichever one it
is, try using the other one and see whether this makes a difference.
Information about malloc is in the F<INSTALL> file in the source
distribution. You can find out whether you are using perl's malloc by
=head2 How can I free an array or hash so my program shrinks?
-You can't. Memory the system allocates to a program will never be
-returned to the system. That's why long-running programs sometimes
-re-exec themselves.
+You can't. On most operating systems, memory allocated to a program
+can never be returned to the system. That's why long-running programs
+sometimes re-exec themselves. Some operating systems (notably, FreeBSD)
+allegedly reclaim large chunks of memory that is no longer used, but
+it doesn't appear to happen with Perl (yet). The Mac appears to be the
+only platform that will reliably (albeit, slowly) return memory to the OS.
However, judicious use of my() on your variables will help make sure
that they go out of scope so that Perl can free up their storage for
executable compiled with sfio (see the F<INSTALL> file in the
distribution) and the mod_fastcgi module (available from
http://www.fastcgi.com/) each of your perl scripts becomes a permanent
-CGI daemon processes.
+CGI daemon process.
Both of these solutions can have far-reaching effects on your system
and on the way you write your CGI scripts, so investigate them with
care.
+See http://www.perl.com/CPAN/modules/by-category/15_World_Wide_Web_HTML_HTTP_CGI/.
+
+A non-free, commerical product, 'The Velocity Engine for Perl',
+(http://www.binevolve.com/ or http://www.binevolve.com/bine/vep) might
+also be worth looking at. It will allow you to increase the performance
+of your perl scripts, upto 25 times faster than normal cgi perl by
+running in persistent perl mode, or 4 to 5 times faster without any
+modification to your existing cgi scripts. Fully functional evaluation
+copies are available from the web site.
+
=head2 How can I hide the source for my Perl program?
Delete it. :-) Seriously, there are a number of (mostly
instead of fixing them, is little security indeed.
You can try using encryption via source filters (Filter::* from CPAN).
-But crackers might be able to decrypt it. You can try using the
-byte-code compiler and interpreter described below, but crackers might
-be able to de-compile it. You can try using the native-code compiler
+But crackers might be able to decrypt it. You can try using the byte
+code compiler and interpreter described below, but crackers might be
+able to de-compile it. You can try using the native-code compiler
described below, but crackers might be able to disassemble it. These
pose varying degrees of difficulty to people wanting to get at your
code, but none can definitively conceal it (this is true of every
blah." We are not lawyers, of course, so you should see a lawyer if
you want to be sure your licence's wording will stand up in court.
-=head2 How can I compile my Perl program into byte-code or C?
+=head2 How can I compile my Perl program into byte code or C?
Malcolm Beattie has written a multifunction backend compiler,
available from CPAN, that can do both these things. It is as of
(like several times faster), but this takes some tweaking of your
code.
-Malcolm will be in charge of the 5.005 release of Perl itself
-to try to unify and merge his compiler and multithreading work into
-the main release.
+The 5.005 release of Perl itself, whose main goal is merging the various
+non-Unix ports back into the one Perl source, will also have preliminary
+(strictly beta) support for Malcolm's compiler and his light-weight
+processes (sometimes called "threads").
You'll probably be astonished to learn that the current version of the
compiler generates a compiled form of your script whose executable is
For example, on one author's system, /usr/bin/perl is only 11k in
size!
-=head2 How can I get '#!perl' to work on [MSDOS,NT,...]?
+In general, the compiler will do nothing to make a Perl program smaller,
+faster, more portable, or more secure. In fact, it will usually hurt
+all of those. The executable will be bigger, your VM system may take
+longer to load the whole thing, the binary is fragile and hard to fix,
+and compilation never stopped software piracy in the form of crackers,
+viruses, or bootleggers. The real advantage of the compiler is merely
+packaging, and once you see the size of what it makes (well, unless
+you use a shared I<libperl.so>), you'll probably want a complete
+Perl install anywayt.
+
+=head2 How can I get '#!perl' to work on [MS-DOS,NT,...]?
For OS/2 just use
(These assume standard Unix shell quoting rules.)
# sum first and last fields
- perl -lane 'print $F[0] + $F[-1]'
+ perl -lane 'print $F[0] + $F[-1]' *
# identify text files
perl -le 'for(@ARGV) {print if -f && -T _}' *
- # remove comments from C program
+ # remove (most) comments from C program
perl -0777 -pe 's{/\*.*?\*/}{}gs' foo.c
# make file a month younger than today, defeating reaper daemons
do I get 500 Errors" or "Why doesn't it run from the browser right
when it runs fine on the command line", see these sources:
- The Idiot's Guide to Solving Perl/CGI Problems, by Tom Christiansen
- http://www.perl.com/perl/faq/idiots-guide.html
+ WWW Security FAQ
+ http://www.w3.org/Security/Faq/
- Frequently Asked Questions about CGI Programming, by Nick Kew
- ftp://rtfm.mit.edu/pub/usenet/news.answers/www/cgi-faq
- http://www3.pair.com/webthing/docs/cgi/faqs/cgifaq.shtml
+ Web FAQ
+ http://www.boutell.com/faq/
- Perl/CGI programming FAQ, by Shishir Gundavaram and Tom Christiansen
- http://www.perl.com/perl/faq/perl-cgi-faq.html
+ CGI FAQ
+ http://www.webthing.com/page.cgi/cgifaq
- The WWW Security FAQ, by Lincoln Stein
- http://www-genome.wi.mit.edu/WWW/faqs/www-security-faq.html
+ HTTP Spec
+ http://www.w3.org/pub/WWW/Protocols/HTTP/
+
+ HTML Spec
+ http://www.w3.org/TR/REC-html40/
+ http://www.w3.org/pub/WWW/MarkUp/
+
+ CGI Spec
+ http://www.w3.org/CGI/
+
+ CGI Security FAQ
+ http://www.go2net.com/people/paulp/cgi-security/safe-cgi.txt
- World Wide Web FAQ, by Thomas Boutell
- http://www.boutell.com/faq/
=head2 Where can I learn about object-oriented Perl programming?
Download the ExtUtils::Embed kit from CPAN and run `make test'. If
the tests pass, read the pods again and again and again. If they
-fail, see L<perlbug> and send a bugreport with the output of
+fail, see L<perlbug> and send a bugreport with the output of
C<make test TEST_VERBOSE=1> along with C<perl -V>.
=head2 When I tried to run my script, I got this message. What does it
=head1 AUTHOR AND COPYRIGHT
-Copyright (c) 1997 Tom Christiansen and Nathan Torkington.
-All rights reserved. See L<perlfaq> for distribution information.
+Copyright (c) 1997, 1998 Tom Christiansen and Nathan Torkington.
+All rights reserved.
+
+When included as an integrated part of the Standard Distribution
+of Perl or of its documentation (printed or otherwise), this works is
+covered under Perl's Artistic Licence. For separate distributions of
+all or part of this FAQ outside of that, see L<perlfaq>.
+
+Irrespective of its distribution, all code examples here are public
+domain. You are permitted and encouraged to use this code and any
+derivatives thereof in your own programs for fun or for profit as you
+see fit. A simple comment in the code giving credit to the FAQ would
+be courteous but is not required.
https://perl5.git.perl.org / perl5.git / blobdiff