3 perlfaq3 - Programming Tools ($Revision: 1.38 $, $Date: 1999/05/23 16:08:30 $)
7 This section of the FAQ answers questions related to programmer tools
8 and programming support.
10 =head2 How do I do (anything)?
12 Have you looked at CPAN (see L<perlfaq2>)? The chances are that
13 someone has already written a module that can solve your problem.
14 Have you read the appropriate man pages? Here's a brief index:
16 Basics perldata, perlvar, perlsyn, perlop, perlsub
17 Execution perlrun, perldebug
19 Objects perlref, perlmod, perlobj, perltie
20 Data Structures perlref, perllol, perldsc
21 Modules perlmod, perlmodlib, perlsub
22 Regexes perlre, perlfunc, perlop, perllocale
23 Moving to perl5 perltrap, perl
24 Linking w/C perlxstut, perlxs, perlcall, perlguts, perlembed
25 Various http://www.perl.com/CPAN/doc/FMTEYEWTK/index.html
26 (not a man-page but still useful)
28 A crude table of contents for the Perl man page set is found in L<perltoc>.
30 =head2 How can I use Perl interactively?
32 The typical approach uses the Perl debugger, described in the
33 perldebug(1) man page, on an ``empty'' program, like this:
37 Now just type in any legal Perl code, and it will be immediately
38 evaluated. You can also examine the symbol table, get stack
39 backtraces, check variable values, set breakpoints, and other
40 operations typically found in symbolic debuggers.
42 =head2 Is there a Perl shell?
44 In general, no. The Shell.pm module (distributed with Perl) makes
45 Perl try commands which aren't part of the Perl language as shell
46 commands. perlsh from the source distribution is simplistic and
47 uninteresting, but may still be what you want.
49 =head2 How do I debug my Perl programs?
51 Have you tried C<use warnings> or used C<-w>? They enable warnings
52 for dubious practices.
54 Have you tried C<use strict>? It prevents you from using symbolic
55 references, makes you predeclare any subroutines that you call as bare
56 words, and (probably most importantly) forces you to predeclare your
57 variables with C<my> or C<our> or C<use vars>.
59 Did you check the returns of each and every system call? The operating
60 system (and thus Perl) tells you whether they worked or not, and if not
63 open(FH, "> /etc/cantwrite")
64 or die "Couldn't write to /etc/cantwrite: $!\n";
66 Did you read L<perltrap>? It's full of gotchas for old and new Perl
67 programmers, and even has sections for those of you who are upgrading
68 from languages like I<awk> and I<C>.
70 Have you tried the Perl debugger, described in L<perldebug>? You can
71 step through your program and see what it's doing and thus work out
72 why what it's doing isn't what it should be doing.
74 =head2 How do I profile my Perl programs?
76 You should get the Devel::DProf module from CPAN, and also use
77 Benchmark.pm from the standard distribution. Benchmark lets you time
78 specific portions of your code, while Devel::DProf gives detailed
79 breakdowns of where your code spends its time.
81 Here's a sample use of Benchmark:
85 @junk = `cat /etc/motd`;
89 'map' => sub { my @a = @junk;
93 'for' => sub { my @a = @junk;
99 This is what it prints (on one machine--your results will be dependent
100 on your hardware, operating system, and the load on your machine):
102 Benchmark: timing 10000 iterations of for, map...
103 for: 4 secs ( 3.97 usr 0.01 sys = 3.98 cpu)
104 map: 6 secs ( 4.97 usr 0.00 sys = 4.97 cpu)
106 Be aware that a good benchmark is very hard to write. It only tests the
107 data you give it, and really proves little about differing complexities
108 of contrasting algorithms.
110 =head2 How do I cross-reference my Perl programs?
112 The B::Xref module, shipped with the new, alpha-release Perl compiler
113 (not the general distribution prior to the 5.005 release), can be used
114 to generate cross-reference reports for Perl programs.
116 perl -MO=Xref[,OPTIONS] scriptname.plx
118 =head2 Is there a pretty-printer (formatter) for Perl?
120 There is no program that will reformat Perl as much as indent(1) does
121 for C. The complex feedback between the scanner and the parser (this
122 feedback is what confuses the vgrind and emacs programs) makes it
123 challenging at best to write a stand-alone Perl parser.
125 Of course, if you simply follow the guidelines in L<perlstyle>, you
126 shouldn't need to reformat. The habit of formatting your code as you
127 write it will help prevent bugs. Your editor can and should help you
128 with this. The perl-mode for emacs can provide a remarkable amount of
129 help with most (but not all) code, and even less programmable editors
130 can provide significant assistance. Tom swears by the following
131 settings in vi and its clones:
136 Now put that in your F<.exrc> file (replacing the caret characters
137 with control characters) and away you go. In insert mode, ^T is
138 for indenting, ^D is for undenting, and ^O is for blockdenting --
139 as it were. If you haven't used the last one, you're missing
140 a lot. A more complete example, with comments, can be found at
141 http://www.perl.com/CPAN-local/authors/id/TOMC/scripts/toms.exrc.gz
143 If you are used to using the I<vgrind> program for printing out nice code
144 to a laser printer, you can take a stab at this using
145 http://www.perl.com/CPAN/doc/misc/tips/working.vgrind.entry, but the
146 results are not particularly satisfying for sophisticated code.
148 The a2ps at http://www.infres.enst.fr/%7Edemaille/a2ps/ does lots of things
149 related to generating nicely printed output of documents.
151 =head2 Is there a ctags for Perl?
153 There's a simple one at
154 http://www.perl.com/CPAN/authors/id/TOMC/scripts/ptags.gz which may do
155 the trick. And if not, it's easy to hack into what you want.
157 =head2 Is there an IDE or Windows Perl Editor?
159 If you're on Unix, you already have an IDE -- Unix itself. This powerful
160 IDE derives from its interoperability, flexibility, and configurability.
161 If you really want to get a feel for Unix-qua-IDE, the best thing to do
162 is to find some high-powered programmer whose native language is Unix.
163 Find someone who has been at this for many years, and just sit back
164 and watch them at work. They have created their own IDE, one that
165 suits their own tastes and aptitudes. Quietly observe them edit files,
166 move them around, compile them, debug them, test them, etc. The entire
167 development *is* integrated, like a top-of-the-line German sports car:
168 functional, powerful, and elegant. You will be absolutely astonished
169 at the speed and ease exhibited by the native speaker of Unix in his
170 home territory. The art and skill of a virtuoso can only be seen to be
171 believed. That is the path to mastery -- all these cobbled little IDEs
172 are expensive toys designed to sell a flashy demo using cheap tricks,
173 and being optimized for immediate but shallow understanding rather than
174 enduring use, are but a dim palimpsest of real tools.
176 In short, you just have to learn the toolbox. However, if you're not
177 on Unix, then your vendor probably didn't bother to provide you with
178 a proper toolbox on the so-called complete system that you forked out
179 your hard-earned cash on.
181 PerlBuilder (XXX URL to follow) is an integrated development environment
182 for Windows that supports Perl development. Perl programs are just plain
183 text, though, so you could download emacs for Windows (???) or a vi clone
184 (vim) which runs on for win32 (http://www.cs.vu.nl/%7Etmgil/vi.html).
185 If you're transferring Windows files to Unix, be sure to transfer in
186 ASCII mode so the ends of lines are appropriately mangled.
188 =head2 Where can I get Perl macros for vi?
190 For a complete version of Tom Christiansen's vi configuration file,
191 see http://www.perl.com/CPAN/authors/Tom_Christiansen/scripts/toms.exrc.gz,
192 the standard benchmark file for vi emulators. This runs best with nvi,
193 the current version of vi out of Berkeley, which incidentally can be built
194 with an embedded Perl interpreter -- see http://www.perl.com/CPAN/src/misc.
196 =head2 Where can I get perl-mode for emacs?
198 Since Emacs version 19 patchlevel 22 or so, there have been both a
199 perl-mode.el and support for the Perl debugger built in. These should
200 come with the standard Emacs 19 distribution.
202 In the Perl source directory, you'll find a directory called "emacs",
203 which contains a cperl-mode that color-codes keywords, provides
204 context-sensitive help, and other nifty things.
206 Note that the perl-mode of emacs will have fits with C<"main'foo">
207 (single quote), and mess up the indentation and highlighting. You
208 are probably using C<"main::foo"> in new Perl code anyway, so this
209 shouldn't be an issue.
211 =head2 How can I use curses with Perl?
213 The Curses module from CPAN provides a dynamically loadable object
214 module interface to a curses library. A small demo can be found at the
215 directory http://www.perl.com/CPAN/authors/Tom_Christiansen/scripts/rep;
216 this program repeats a command and updates the screen as needed, rendering
217 B<rep ps axu> similar to B<top>.
219 =head2 How can I use X or Tk with Perl?
221 Tk is a completely Perl-based, object-oriented interface to the Tk toolkit
222 that doesn't force you to use Tcl just to get at Tk. Sx is an interface
223 to the Athena Widget set. Both are available from CPAN. See the
224 directory http://www.perl.com/CPAN/modules/by-category/08_User_Interfaces/
226 Invaluable for Perl/Tk programming are: the Perl/Tk FAQ at
227 http://w4.lns.cornell.edu/%7Epvhp/ptk/ptkTOC.html , the Perl/Tk Reference
229 http://www.perl.com/CPAN-local/authors/Stephen_O_Lidie/ , and the
231 http://www-users.cs.umn.edu/%7Eamundson/perl/perltk/toc.html .
233 =head2 How can I generate simple menus without using CGI or Tk?
235 The http://www.perl.com/CPAN/authors/id/SKUNZ/perlmenu.v4.0.tar.gz
236 module, which is curses-based, can help with this.
238 =head2 What is undump?
240 See the next questions.
242 =head2 How can I make my Perl program run faster?
244 The best way to do this is to come up with a better algorithm. This
245 can often make a dramatic difference. Chapter 8 in the Camel has some
246 efficiency tips in it you might want to look at. Jon Bentley's book
247 ``Programming Pearls'' (that's not a misspelling!) has some good tips
248 on optimization, too. Advice on benchmarking boils down to: benchmark
249 and profile to make sure you're optimizing the right part, look for
250 better algorithms instead of microtuning your code, and when all else
251 fails consider just buying faster hardware.
253 A different approach is to autoload seldom-used Perl code. See the
254 AutoSplit and AutoLoader modules in the standard distribution for
255 that. Or you could locate the bottleneck and think about writing just
256 that part in C, the way we used to take bottlenecks in C code and
257 write them in assembler. Similar to rewriting in C is the use of
258 modules that have critical sections written in C (for instance, the
259 PDL module from CPAN).
261 In some cases, it may be worth it to use the backend compiler to
262 produce byte code (saving compilation time) or compile into C, which
263 will certainly save compilation time and sometimes a small amount (but
264 not much) execution time. See the question about compiling your Perl
265 programs for more on the compiler--the wins aren't as obvious as you'd
268 If you're currently linking your perl executable to a shared I<libc.so>,
269 you can often gain a 10-25% performance benefit by rebuilding it to
270 link with a static libc.a instead. This will make a bigger perl
271 executable, but your Perl programs (and programmers) may thank you for
272 it. See the F<INSTALL> file in the source distribution for more
275 Unsubstantiated reports allege that Perl interpreters that use sfio
276 outperform those that don't (for I/O intensive applications). To try
277 this, see the F<INSTALL> file in the source distribution, especially
278 the ``Selecting File I/O mechanisms'' section.
280 The undump program was an old attempt to speed up your Perl program
281 by storing the already-compiled form to disk. This is no longer
282 a viable option, as it only worked on a few architectures, and
283 wasn't a good solution anyway.
285 =head2 How can I make my Perl program take less memory?
287 When it comes to time-space tradeoffs, Perl nearly always prefers to
288 throw memory at a problem. Scalars in Perl use more memory than
289 strings in C, arrays take more than that, and hashes use even more. While
290 there's still a lot to be done, recent releases have been addressing
291 these issues. For example, as of 5.004, duplicate hash keys are
292 shared amongst all hashes using them, so require no reallocation.
294 In some cases, using substr() or vec() to simulate arrays can be
295 highly beneficial. For example, an array of a thousand booleans will
296 take at least 20,000 bytes of space, but it can be turned into one
297 125-byte bit vector for a considerable memory savings. The standard
298 Tie::SubstrHash module can also help for certain types of data
299 structure. If you're working with specialist data structures
300 (matrices, for instance) modules that implement these in C may use
301 less memory than equivalent Perl modules.
303 Another thing to try is learning whether your Perl was compiled with
304 the system malloc or with Perl's builtin malloc. Whichever one it
305 is, try using the other one and see whether this makes a difference.
306 Information about malloc is in the F<INSTALL> file in the source
307 distribution. You can find out whether you are using perl's malloc by
308 typing C<perl -V:usemymalloc>.
310 =head2 Is it unsafe to return a pointer to local data?
312 No, Perl's garbage collection system takes care of this.
320 push @many, makeone();
323 print $many[4][5], "\n";
327 =head2 How can I free an array or hash so my program shrinks?
329 You can't. On most operating systems, memory allocated to a program
330 can never be returned to the system. That's why long-running programs
331 sometimes re-exec themselves. Some operating systems (notably,
332 FreeBSD and Linux) allegedly reclaim large chunks of memory that is no
333 longer used, but it doesn't appear to happen with Perl (yet). The Mac
334 appears to be the only platform that will reliably (albeit, slowly)
335 return memory to the OS.
337 We've had reports that on Linux (Redhat 5.1) on Intel, C<undef
338 $scalar> will return memory to the system, while on Solaris 2.6 it
339 won't. In general, try it yourself and see.
341 However, judicious use of my() on your variables will help make sure
342 that they go out of scope so that Perl can free up their storage for
343 use in other parts of your program. A global variable, of course, never
344 goes out of scope, so you can't get its space automatically reclaimed,
345 although undef()ing and/or delete()ing it will achieve the same effect.
346 In general, memory allocation and de-allocation isn't something you can
347 or should be worrying about much in Perl, but even this capability
348 (preallocation of data types) is in the works.
350 =head2 How can I make my CGI script more efficient?
352 Beyond the normal measures described to make general Perl programs
353 faster or smaller, a CGI program has additional issues. It may be run
354 several times per second. Given that each time it runs it will need
355 to be re-compiled and will often allocate a megabyte or more of system
356 memory, this can be a killer. Compiling into C B<isn't going to help
357 you> because the process start-up overhead is where the bottleneck is.
359 There are two popular ways to avoid this overhead. One solution
360 involves running the Apache HTTP server (available from
361 http://www.apache.org/) with either of the mod_perl or mod_fastcgi
364 With mod_perl and the Apache::Registry module (distributed with
365 mod_perl), httpd will run with an embedded Perl interpreter which
366 pre-compiles your script and then executes it within the same address
367 space without forking. The Apache extension also gives Perl access to
368 the internal server API, so modules written in Perl can do just about
369 anything a module written in C can. For more on mod_perl, see
370 http://perl.apache.org/
372 With the FCGI module (from CPAN) and the mod_fastcgi
373 module (available from http://www.fastcgi.com/) each of your Perl
374 programs becomes a permanent CGI daemon process.
376 Both of these solutions can have far-reaching effects on your system
377 and on the way you write your CGI programs, so investigate them with
380 See http://www.perl.com/CPAN/modules/by-category/15_World_Wide_Web_HTML_HTTP_CGI/ .
382 A non-free, commercial product, ``The Velocity Engine for Perl'',
383 (http://www.binevolve.com/ or http://www.binevolve.com/velocigen/) might
384 also be worth looking at. It will allow you to increase the performance
385 of your Perl programs, up to 25 times faster than normal CGI Perl by
386 running in persistent Perl mode, or 4 to 5 times faster without any
387 modification to your existing CGI programs. Fully functional evaluation
388 copies are available from the web site.
390 =head2 How can I hide the source for my Perl program?
392 Delete it. :-) Seriously, there are a number of (mostly
393 unsatisfactory) solutions with varying levels of ``security''.
395 First of all, however, you I<can't> take away read permission, because
396 the source code has to be readable in order to be compiled and
397 interpreted. (That doesn't mean that a CGI script's source is
398 readable by people on the web, though, only by people with access to
399 the filesystem) So you have to leave the permissions at the socially
402 Some people regard this as a security problem. If your program does
403 insecure things, and relies on people not knowing how to exploit those
404 insecurities, it is not secure. It is often possible for someone to
405 determine the insecure things and exploit them without viewing the
406 source. Security through obscurity, the name for hiding your bugs
407 instead of fixing them, is little security indeed.
409 You can try using encryption via source filters (Filter::* from CPAN),
410 but any decent programmer will be able to decrypt it. You can try using
411 the byte code compiler and interpreter described below, but the curious
412 might still be able to de-compile it. You can try using the native-code
413 compiler described below, but crackers might be able to disassemble it.
414 These pose varying degrees of difficulty to people wanting to get at
415 your code, but none can definitively conceal it (this is true of every
416 language, not just Perl).
418 If you're concerned about people profiting from your code, then the
419 bottom line is that nothing but a restrictive license will give you
420 legal security. License your software and pepper it with threatening
421 statements like ``This is unpublished proprietary software of XYZ Corp.
422 Your access to it does not give you permission to use it blah blah
423 blah.'' We are not lawyers, of course, so you should see a lawyer if
424 you want to be sure your license's wording will stand up in court.
426 =head2 How can I compile my Perl program into byte code or C?
428 Malcolm Beattie has written a multifunction backend compiler,
429 available from CPAN, that can do both these things. It is included
430 in the perl5.005 release, but is still considered experimental.
431 This means it's fun to play with if you're a programmer but not
432 really for people looking for turn-key solutions.
434 Merely compiling into C does not in and of itself guarantee that your
435 code will run very much faster. That's because except for lucky cases
436 where a lot of native type inferencing is possible, the normal Perl
437 run time system is still present and so your program will take just as
438 long to run and be just as big. Most programs save little more than
439 compilation time, leaving execution no more than 10-30% faster. A few
440 rare programs actually benefit significantly (like several times
441 faster), but this takes some tweaking of your code.
443 You'll probably be astonished to learn that the current version of the
444 compiler generates a compiled form of your script whose executable is
445 just as big as the original perl executable, and then some. That's
446 because as currently written, all programs are prepared for a full
447 eval() statement. You can tremendously reduce this cost by building a
448 shared I<libperl.so> library and linking against that. See the
449 F<INSTALL> podfile in the Perl source distribution for details. If
450 you link your main perl binary with this, it will make it minuscule.
451 For example, on one author's system, F</usr/bin/perl> is only 11k in
454 In general, the compiler will do nothing to make a Perl program smaller,
455 faster, more portable, or more secure. In fact, it will usually hurt
456 all of those. The executable will be bigger, your VM system may take
457 longer to load the whole thing, the binary is fragile and hard to fix,
458 and compilation never stopped software piracy in the form of crackers,
459 viruses, or bootleggers. The real advantage of the compiler is merely
460 packaging, and once you see the size of what it makes (well, unless
461 you use a shared I<libperl.so>), you'll probably want a complete
464 =head2 How can I compile Perl into Java?
466 You can't. Not yet, anyway. You can integrate Java and Perl with the
467 Perl Resource Kit from O'Reilly and Associates. See
468 http://www.oreilly.com/catalog/prkunix/ for more information.
469 The Java interface will be supported in the core 5.6 release
472 =head2 How can I get C<#!perl> to work on [MS-DOS,NT,...]?
476 extproc perl -S -your_switches
478 as the first line in C<*.cmd> file (C<-S> due to a bug in cmd.exe's
479 `extproc' handling). For DOS one should first invent a corresponding
480 batch file, and codify it in C<ALTERNATIVE_SHEBANG> (see the
481 F<INSTALL> file in the source distribution for more information).
483 The Win95/NT installation, when using the ActiveState port of Perl,
484 will modify the Registry to associate the C<.pl> extension with the
485 perl interpreter. If you install another port, perhaps even building
486 your own Win95/NT Perl from the standard sources by using a Windows port
487 of gcc (e.g., with cygwin or mingw32), then you'll have to modify
488 the Registry yourself. In addition to associating C<.pl> with the
489 interpreter, NT people can use: C<SET PATHEXT=%PATHEXT%;.PL> to let them
490 run the program C<install-linux.pl> merely by typing C<install-linux>.
492 Macintosh Perl programs will have the appropriate Creator and
493 Type, so that double-clicking them will invoke the Perl application.
495 I<IMPORTANT!>: Whatever you do, PLEASE don't get frustrated, and just
496 throw the perl interpreter into your cgi-bin directory, in order to
497 get your programs working for a web server. This is an EXTREMELY big
498 security risk. Take the time to figure out how to do it correctly.
500 =head2 Can I write useful Perl programs on the command line?
502 Yes. Read L<perlrun> for more information. Some examples follow.
503 (These assume standard Unix shell quoting rules.)
505 # sum first and last fields
506 perl -lane 'print $F[0] + $F[-1]' *
508 # identify text files
509 perl -le 'for(@ARGV) {print if -f && -T _}' *
511 # remove (most) comments from C program
512 perl -0777 -pe 's{/\*.*?\*/}{}gs' foo.c
514 # make file a month younger than today, defeating reaper daemons
515 perl -e '$X=24*60*60; utime(time(),time() + 30 * $X,@ARGV)' *
517 # find first unused uid
518 perl -le '$i++ while getpwuid($i); print $i'
520 # display reasonable manpath
521 echo $PATH | perl -nl -072 -e '
522 s![^/+]*$!man!&&-d&&!$s{$_}++&&push@m,$_;END{print"@m"}'
524 OK, the last one was actually an Obfuscated Perl Contest entry. :-)
526 =head2 Why don't Perl one-liners work on my DOS/Mac/VMS system?
528 The problem is usually that the command interpreters on those systems
529 have rather different ideas about quoting than the Unix shells under
530 which the one-liners were created. On some systems, you may have to
531 change single-quotes to double ones, which you must I<NOT> do on Unix
532 or Plan9 systems. You might also have to change a single % to a %%.
537 perl -e 'print "Hello world\n"'
540 perl -e "print \"Hello world\n\""
543 print "Hello world\n"
544 (then Run "Myscript" or Shift-Command-R)
547 perl -e "print ""Hello world\n"""
549 The problem is that none of this is reliable: it depends on the
550 command interpreter. Under Unix, the first two often work. Under DOS,
551 it's entirely possible neither works. If 4DOS was the command shell,
552 you'd probably have better luck like this:
554 perl -e "print <Ctrl-x>"Hello world\n<Ctrl-x>""
556 Under the Mac, it depends which environment you are using. The MacPerl
557 shell, or MPW, is much like Unix shells in its support for several
558 quoting variants, except that it makes free use of the Mac's non-ASCII
559 characters as control characters.
561 Using qq(), q(), and qx(), instead of "double quotes", 'single
562 quotes', and `backticks`, may make one-liners easier to write.
564 There is no general solution to all of this. It is a mess, pure and
565 simple. Sucks to be away from Unix, huh? :-)
567 [Some of this answer was contributed by Kenneth Albanowski.]
569 =head2 Where can I learn about CGI or Web programming in Perl?
571 For modules, get the CGI or LWP modules from CPAN. For textbooks,
572 see the two especially dedicated to web stuff in the question on
573 books. For problems and questions related to the web, like ``Why
574 do I get 500 Errors'' or ``Why doesn't it run from the browser right
575 when it runs fine on the command line'', see these sources:
578 http://www.w3.org/Security/Faq/
581 http://www.boutell.com/faq/
584 http://www.webthing.com/tutorials/cgifaq.html
587 http://www.w3.org/pub/WWW/Protocols/HTTP/
590 http://www.w3.org/TR/REC-html40/
591 http://www.w3.org/pub/WWW/MarkUp/
594 http://www.w3.org/CGI/
597 http://www.go2net.com/people/paulp/cgi-security/safe-cgi.txt
600 =head2 Where can I learn about object-oriented Perl programming?
602 A good place to start is L<perltoot>, and you can use L<perlobj> and
603 L<perlbot> for reference. Perltoot didn't come out until the 5.004
604 release, but you can get a copy (in pod, html, or postscript) from
605 http://www.perl.com/CPAN/doc/FMTEYEWTK/ .
607 =head2 Where can I learn about linking C with Perl? [h2xs, xsubpp]
609 If you want to call C from Perl, start with L<perlxstut>,
610 moving on to L<perlxs>, L<xsubpp>, and L<perlguts>. If you want to
611 call Perl from C, then read L<perlembed>, L<perlcall>, and
612 L<perlguts>. Don't forget that you can learn a lot from looking at
613 how the authors of existing extension modules wrote their code and
614 solved their problems.
616 =head2 I've read perlembed, perlguts, etc., but I can't embed perl in
617 my C program, what am I doing wrong?
619 Download the ExtUtils::Embed kit from CPAN and run `make test'. If
620 the tests pass, read the pods again and again and again. If they
621 fail, see L<perlbug> and send a bug report with the output of
622 C<make test TEST_VERBOSE=1> along with C<perl -V>.
624 =head2 When I tried to run my script, I got this message. What does it
627 A complete list of Perl's error messages and warnings with explanatory
628 text can be found in L<perldiag>. You can also use the splain program
629 (distributed with Perl) to explain the error messages:
631 perl program 2>diag.out
632 splain [-v] [-p] diag.out
634 or change your program to explain the messages for you:
640 use diagnostics -verbose;
642 =head2 What's MakeMaker?
644 This module (part of the standard Perl distribution) is designed to
645 write a Makefile for an extension module from a Makefile.PL. For more
646 information, see L<ExtUtils::MakeMaker>.
648 =head1 AUTHOR AND COPYRIGHT
650 Copyright (c) 1997-1999 Tom Christiansen and Nathan Torkington.
653 When included as an integrated part of the Standard Distribution
654 of Perl or of its documentation (printed or otherwise), this works is
655 covered under Perl's Artistic License. For separate distributions of
656 all or part of this FAQ outside of that, see L<perlfaq>.
658 Irrespective of its distribution, all code examples here are in the public
659 domain. You are permitted and encouraged to use this code and any
660 derivatives thereof in your own programs for fun or for profit as you
661 see fit. A simple comment in the code giving credit to the FAQ would
662 be courteous but is not required.