IRIX Base Documentation 1998 November/IRIX 6.5.2 Base Documentation November 1998.img/usr/share/catman/u_man/cat1/perlfaq3.z/perlfaq3

Text File | 1998-10-30 | 34KB | 727 lines

PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))                                                        PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))



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     perlfaq3 - Programming Tools ($Revision: 1.22 $, $Date: 1997/04/24
     22:43:42 $)

DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
     This section of the FAQ answers questions related to programmer tools and
     programming support.

     HHHHoooowwww ddddoooo IIII ddddoooo ((((aaaannnnyyyytttthhhhiiiinnnngggg))))????

     Have you looked at CPAN (see the _p_e_r_l_f_a_q_2 manpage)?  The chances are that
     someone has already written a module that can solve your problem.  Have
     you read the appropriate man pages?  Here's a brief index:

             Objects         perlref, perlmod, perlobj, perltie
             Data Structures perlref, perllol, perldsc
             Modules         perlmod, perlmodlib, perlsub
             Regexps         perlre, perlfunc, perlop
             Moving to perl5 perltrap, perl
             Linking w/C     perlxstut, perlxs, perlcall, perlguts, perlembed
             Various         http://www.perl.com/CPAN/doc/FMTEYEWTK/index.html
                             (not a man-page but still useful)

     the _p_e_r_l_t_o_c manpage provides a crude table of contents for the perl man
     page set.

     HHHHoooowwww ccccaaaannnn IIII uuuusssseeee PPPPeeeerrrrllll iiiinnnntttteeeerrrraaaaccccttttiiiivvvveeeellllyyyy????

     The typical approach uses the Perl debugger, described in the
     _p_e_r_l_d_e_b_u_g(1) man page, on an "empty" program, like this:

         perl -de 42

     Now just type in any legal Perl code, and it will be immediately
     evaluated.  You can also examine the symbol table, get stack backtraces,
     check variable values, set breakpoints, and other operations typically
     found in symbolic debuggers

     IIIIssss tttthhhheeeerrrreeee aaaa PPPPeeeerrrrllll sssshhhheeeellllllll????

     In general, no.  The Shell.pm module (distributed with perl) makes perl
     try commands which aren't part of the Perl language as shell commands.
     perlsh from the source distribution is simplistic and uninteresting, but
     may still be what you want.

     HHHHoooowwww ddddoooo IIII ddddeeeebbbbuuuugggg mmmmyyyy PPPPeeeerrrrllll pppprrrrooooggggrrrraaaammmmssss????

     Have you used -w?

     Have you tried use strict?





                                                                        PPPPaaaaggggeeee 1111






PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))                                                        PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))



     Did you check the returns of each and every system call?

     Did you read the _p_e_r_l_t_r_a_p manpage?

     Have you tried the Perl debugger, described in the _p_e_r_l_d_e_b_u_g manpage?

     HHHHoooowwww ddddoooo IIII pppprrrrooooffffiiiilllleeee mmmmyyyy PPPPeeeerrrrllll pppprrrrooooggggrrrraaaammmmssss????

     You should get the Devel::DProf module from CPAN, and also use
     Benchmark.pm from the standard distribution.  Benchmark lets you time
     specific portions of your code, while Devel::DProf gives detailed
     breakdowns of where your code spends its time.

     HHHHoooowwww ddddoooo IIII ccccrrrroooossssssss----rrrreeeeffffeeeerrrreeeennnncccceeee mmmmyyyy PPPPeeeerrrrllll pppprrrrooooggggrrrraaaammmmssss????

     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.

         perl -MO=Xref[,OPTIONS] foo.pl


     IIIIssss tttthhhheeeerrrreeee aaaa pppprrrreeeettttttttyyyy----pppprrrriiiinnnntttteeeerrrr ((((ffffoooorrrrmmmmaaaatttttttteeeerrrr)))) ffffoooorrrr PPPPeeeerrrrllll????

     There is no program that will reformat Perl as much as _i_n_d_e_n_t(1) will do
     for C.  The complex feedback between the scanner and the parser (this
     feedback is what confuses the vgrind and emacs programs) makes it
     challenging at best to write a stand-alone Perl parser.

     Of course, if you simply follow the guidelines in the _p_e_r_l_s_t_y_l_e manpage,
     you shouldn't need to reformat.

     Your editor can and should help you with source formatting.  The perl-
     mode for emacs can provide a remarkable amount of help with most (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 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.

     IIIIssss tttthhhheeeerrrreeee aaaa ccccttttaaaaggggssss ffffoooorrrr PPPPeeeerrrrllll????

     There's a simple one at
     http://www.perl.com/CPAN/authors/id/TOMC/scripts/ptags.gz which may do
     the trick.

     WWWWhhhheeeerrrreeee ccccaaaannnn IIII ggggeeeetttt PPPPeeeerrrrllll mmmmaaaaccccrrrroooossss ffffoooorrrr vvvviiii????






                                                                        PPPPaaaaggggeeee 2222






PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))                                                        PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))



     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 .

     WWWWhhhheeeerrrreeee ccccaaaannnn IIII ggggeeeetttt ppppeeeerrrrllll----mmmmooooddddeeee ffffoooorrrr eeeemmmmaaaaccccssss????

     Since Emacs version 19 patchlevel 22 or so, there have been both a perl-
     mode.el and support for the perl debugger built in.  These should come
     with the standard Emacs 19 distribution.

     In the perl source directory, you'll find a directory called "emacs",
     which contains a cperl-mode that color-codes keywords, provides context-
     sensitive help, and other nifty things.

     Note that the perl-mode of emacs will have fits with "main'foo" (single
     quote), and mess up the indentation and hilighting.  You should be using
     "main::foo", anyway.

     HHHHoooowwww ccccaaaannnn IIII uuuusssseeee ccccuuuurrrrsssseeeessss wwwwiiiitttthhhh PPPPeeeerrrrllll????

     The Curses module from CPAN provides a dynamically loadable object module
     interface to a curses library.

     HHHHoooowwww ccccaaaannnn IIII uuuusssseeee XXXX oooorrrr TTTTkkkk wwwwiiiitttthhhh PPPPeeeerrrrllll????

     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.

     HHHHoooowwww ccccaaaannnn IIII ggggeeeennnneeeerrrraaaatttteeee ssssiiiimmmmpppplllleeee mmmmeeeennnnuuuussss wwwwiiiitttthhhhoooouuuutttt uuuussssiiiinnnngggg CCCCGGGGIIII oooorrrr TTTTkkkk????

     The http://www.perl.com/CPAN/authors/id/SKUNZ/perlmenu.v4.0.tar.gz
     module, which is curses-based, can help with this.

     CCCCaaaannnn IIII ddddyyyynnnnaaaammmmiiiiccccaaaallllllllyyyy llllooooaaaadddd CCCC rrrroooouuuuttttiiiinnnneeeessss iiiinnnnttttoooo PPPPeeeerrrrllll????

     If your system architecture supports it, then the standard perl on your
     system should also provide you with this via the DynaLoader module.  Read
     the _p_e_r_l_x_s_t_u_t manpage for details.

     WWWWhhhhaaaatttt iiiissss uuuunnnndddduuuummmmpppp????

     See the next questions.

     HHHHoooowwww ccccaaaannnn IIII mmmmaaaakkkkeeee mmmmyyyy PPPPeeeerrrrllll pppprrrrooooggggrrrraaaammmm rrrruuuunnnn ffffaaaasssstttteeeerrrr????

     The best way to do this is to come up with a better algorithm.  This can
     often make a dramatic difference.  Chapter 8 in the Camel has some
     efficiency tips in it you might want to look at.




                                                                        PPPPaaaaggggeeee 3333






PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))                                                        PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))



     Other approaches include autoloading seldom-used Perl code.  See the
     AutoSplit and AutoLoader modules in the standard distribution for that.
     Or you could locate the bottleneck and think about writing just that part
     in C, the way we used to take bottlenecks in C code and write them in
     assembler.  Similar to rewriting in C is the use of modules that have
     critical sections written in C (for instance, the PDL module from CPAN).

     In some cases, it may be worth it to use the backend compiler to produce
     byte code (saving compilation time) or compile into C, which will
     certainly save compilation time and sometimes a small amount (but not
     much) execution time.  See the question about compiling your Perl
     programs.

     If you're currently linking your perl executable to a shared libc.so, you
     can often gain a 10-25% performance benefit by rebuilding it to link with
     a static libc.a instead.  This will make a bigger perl executable, but
     your Perl programs (and programmers) may thank you for it.  See the
     _I_N_S_T_A_L_L file in the source distribution for more information.

     Unsubstantiated reports allege that Perl interpreters that use sfio
     outperform those that don't (for IO intensive applications).  To try
     this, see the _I_N_S_T_A_L_L file in the source distribution, especially the
     "Selecting File IO mechanisms" section.

     The undump program was an old attempt to speed up your Perl program by
     storing the already-compiled form to disk.  This is no longer a viable
     option, as it only worked on a few architectures, and wasn't a good
     solution anyway.

     HHHHoooowwww ccccaaaannnn IIII mmmmaaaakkkkeeee mmmmyyyy PPPPeeeerrrrllll pppprrrrooooggggrrrraaaammmm ttttaaaakkkkeeee lllleeeessssssss mmmmeeeemmmmoooorrrryyyy????

     When it comes to time-space tradeoffs, Perl nearly always prefers to
     throw memory at a problem.  Scalars in Perl use more memory than strings
     in C, arrays take more that, and hashes use even more.  While there's
     still a lot to be done, recent releases have been addressing these
     issues.  For example, as of 5.004, duplicate hash keys are shared amongst
     all hashes using them, so require no reallocation.

     In some cases, using _s_u_b_s_t_r() or _v_e_c() to simulate arrays can be highly
     beneficial.  For example, an array of a thousand booleans will take at
     least 20,000 bytes of space, but it can be turned into one 125-byte bit
     vector for a considerable memory savings.  The standard Tie::SubstrHash
     module can also help for certain types of data structure.  If you're
     working with specialist data structures (matrices, for instance) modules
     that implement these in C may use 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 builtin malloc.  Whichever one it is, try
     using the other one and see whether this makes a difference.  Information
     about malloc is in the _I_N_S_T_A_L_L file in the source distribution.  You can
     find out whether you are using perl's malloc by typing perl



                                                                        PPPPaaaaggggeeee 4444






PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))                                                        PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))



     -V:usemymalloc.

     IIIIssss iiiitttt uuuunnnnssssaaaaffffeeee ttttoooo rrrreeeettttuuuurrrrnnnn aaaa ppppooooiiiinnnntttteeeerrrr ttttoooo llllooooccccaaaallll ddddaaaattttaaaa????

     No, Perl's garbage collection system takes care of this.

         sub makeone {
             my @a = ( 1 .. 10 );
             return \@a;
         }

         for $i ( 1 .. 10 ) {
             push @many, makeone();
         }

         print $many[4][5], "\n";

         print "@many\n";


     HHHHoooowwww ccccaaaannnn IIII ffffrrrreeeeeeee aaaannnn aaaarrrrrrrraaaayyyy oooorrrr hhhhaaaasssshhhh ssssoooo mmmmyyyy pppprrrrooooggggrrrraaaammmm sssshhhhrrrriiiinnnnkkkkssss????

     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.

     However, judicious use of _m_y() on your variables will help make sure that
     they go out of scope so that Perl can free up their storage for use in
     other parts of your program.  (NB: _m_y() variables also execute about 10%
     faster than globals.)  A global variable, of course, never goes out of
     scope, so you can't get its space automatically reclaimed, although
     _u_n_d_e_f()ing and/or _d_e_l_e_t_e()ing it will achieve the same effect.  In
     general, memory allocation and de-allocation isn't something you can or
     should be worrying about much in Perl, but even this capability
     (preallocation of data types) is in the works.

     HHHHoooowwww ccccaaaannnn IIII mmmmaaaakkkkeeee mmmmyyyy CCCCGGGGIIII ssssccccrrrriiiipppptttt mmmmoooorrrreeee eeeeffffffffiiiicccciiiieeeennnntttt????

     Beyond the normal measures described to make general Perl programs faster
     or smaller, a CGI program has additional issues.  It may be run several
     times per second.  Given that each time it runs it will need to be re-
     compiled and will often allocate a megabyte or more of system memory,
     this can be a killer.  Compiling into C iiiissssnnnn''''tttt ggggooooiiiinnnngggg ttttoooo hhhheeeellllpppp yyyyoooouuuu because
     the process start-up overhead is where the bottleneck is.

     There are at least two popular ways to avoid this overhead.  One solution
     involves running the Apache HTTP server (available from
     http://www.apache.org/) with either of the mod_perl or mod_fastcgi plugin
     modules.  With mod_perl and the Apache::* modules (from CPAN), httpd will
     run with an embedded Perl interpreter which pre-compiles your script and
     then executes it within the same address space without forking.  The
     Apache extension also gives Perl access to the internal server API, so



                                                                        PPPPaaaaggggeeee 5555






PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))                                                        PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))



     modules written in Perl can do just about anything a module written in C
     can.  With the FCGI module (from CPAN), a Perl executable compiled with
     sfio (see the _I_N_S_T_A_L_L 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.

     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.

     HHHHoooowwww ccccaaaannnn IIII hhhhiiiiddddeeee tttthhhheeee ssssoooouuuurrrrcccceeee ffffoooorrrr mmmmyyyy PPPPeeeerrrrllll pppprrrrooooggggrrrraaaammmm????

     Delete it. :-) Seriously, there are a number of (mostly unsatisfactory)
     solutions with varying levels of "security".

     First of all, however, you _c_a_n'_t take away read permission, because the
     source code has to be readable in order to be compiled and interpreted.
     (That doesn't mean that a CGI script's source is readable by people on
     the web, though.)  So you have to leave the permissions at the socially
     friendly 0755 level.

     Some people regard this as a security problem.  If your program does
     insecure things, and relies on people not knowing how to exploit those
     insecurities, it is not secure.  It is often possible for someone to
     determine the insecure things and exploit them without viewing the
     source.  Security through obscurity, the name for hiding your bugs
     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 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 language, not just Perl).

     If you're concerned about people profiting from your code, then the
     bottom line is that nothing but a restrictive licence will give you legal
     security.  License your software and pepper it with threatening
     statements like "This is unpublished proprietary software of XYZ Corp.
     Your access to it does not give you permission to use it blah blah 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.

     HHHHoooowwww ccccaaaannnn IIII ccccoooommmmppppiiiilllleeee mmmmyyyy PPPPeeeerrrrllll pppprrrrooooggggrrrraaaammmm iiiinnnnttttoooo bbbbyyyytttteeee ccccooooddddeeee oooorrrr CCCC????

     Malcolm Beattie has written a multifunction backend compiler, available
     from CPAN, that can do both these things.  It is as of Feb-1997 in late
     alpha release, which means it's fun to play with if you're a programmer
     but not really for people looking for turn-key solutions.






                                                                        PPPPaaaaggggeeee 6666






PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))                                                        PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))



     _P_l_e_a_s_e understand that merely compiling into C does not in and of itself
     guarantee that your code will run very much faster.  That's because
     except for lucky cases where a lot of native type inferencing is
     possible, the normal Perl run time system is still present and thus will
     still take just as long to run and be just as big.  Most programs save
     little more than compilation time, leaving execution no more than 10-30%
     faster.  A few rare programs actually benefit significantly (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.

     You'll probably be astonished to learn that the current version of the
     compiler generates a compiled form of your script whose executable is
     just as big as the original perl executable, and then some.  That's
     because as currently written, all programs are prepared for a full _e_v_a_l()
     statement.  You can tremendously reduce this cost by building a shared
     libperl.so library and linking against that.  See the _I_N_S_T_A_L_L podfile in
     the perl source distribution for details.  If you link your main perl
     binary with this, it will make it miniscule.  For example, on one
     author's system, /usr/bin/perl is only 11k in size!

     HHHHoooowwww ccccaaaannnn IIII ggggeeeetttt ''''####!!!!ppppeeeerrrrllll'''' ttttoooo wwwwoooorrrrkkkk oooonnnn [[[[MMMMSSSS----DDDDOOOOSSSS,,,,NNNNTTTT,,,,............]]]]????

     For OS/2 just use

         extproc perl -S -your_switches

     as the first line in *.cmd file (-S due to a bug in cmd.exe's `extproc'
     handling).  For DOS one should first invent a corresponding batch file,
     and codify it in ALTERNATIVE_SHEBANG (see the _I_N_S_T_A_L_L file in the source
     distribution for more information).

     The Win95/NT installation, when using the Activeware port of Perl, will
     modify the Registry to associate the .pl extension with the perl
     interpreter.  If you install another port, or (eventually) build your own
     Win95/NT Perl using WinGCC, then you'll have to modify the Registry
     yourself.

     Macintosh perl scripts will have the the appropriate Creator and Type, so
     that double-clicking them will invoke the perl application.

     _I_M_P_O_R_T_A_N_T!: Whatever you do, PLEASE don't get frustrated, and just throw
     the perl interpreter into your cgi-bin directory, in order to get your
     scripts working for a web server.  This is an EXTREMELY big security
     risk.  Take the time to figure out how to do it correctly.

     CCCCaaaannnn IIII wwwwrrrriiiitttteeee uuuusssseeeeffffuuuullll ppppeeeerrrrllll pppprrrrooooggggrrrraaaammmmssss oooonnnn tttthhhheeee ccccoooommmmmmmmaaaannnndddd lllliiiinnnneeee????






                                                                        PPPPaaaaggggeeee 7777






PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))                                                        PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))



     Yes.  Read the _p_e_r_l_r_u_n manpage for more information.  Some examples
     follow.  (These assume standard Unix shell quoting rules.)

         # sum first and last fields
         perl -lane 'print $F[0] + $F[-1]'

         # identify text files
         perl -le 'for(@ARGV) {print if -f && -T _}' *

         # remove comments from C program
         perl -0777 -pe 's{/\*.*?\*/}{}gs' foo.c

         # make file a month younger than today, defeating reaper daemons
         perl -e '$X=24*60*60; utime(time(),time() + 30 * $X,@ARGV)' *

         # find first unused uid
         perl -le '$i++ while getpwuid($i); print $i'

         # display reasonable manpath
         echo $PATH | perl -nl -072 -e '
             s![^/+]*$!man!&&-d&&!$s{$_}++&&push@m,$_;END{print"@m"}'

     Ok, the last one was actually an obfuscated perl entry. :-)

     WWWWhhhhyyyy ddddoooonnnn''''tttt ppppeeeerrrrllll oooonnnneeee----lllliiiinnnneeeerrrrssss wwwwoooorrrrkkkk oooonnnn mmmmyyyy DDDDOOOOSSSS////MMMMaaaacccc////VVVVMMMMSSSS ssssyyyysssstttteeeemmmm????

     The problem is usually that the command interpreters on those systems
     have rather different ideas about quoting than the Unix shells under
     which the one-liners were created.  On some systems, you may have to
     change single-quotes to double ones, which you must _N_O_T do on Unix or
     Plan9 systems.  You might also have to change a single % to a %%.

     For example:

         # Unix
         perl -e 'print "Hello world\n"'

         # DOS, etc.
         perl -e "print \"Hello world\n\""

         # Mac
         print "Hello world\n"
          (then Run "Myscript" or Shift-Command-R)

         # VMS
         perl -e "print ""Hello world\n"""

     The problem is that none of this is reliable: it depends on the command
     interpreter.  Under Unix, the first two often work. Under DOS, it's
     entirely possible neither works.  If 4DOS was the command shell, I'd
     probably have better luck like this:




                                                                        PPPPaaaaggggeeee 8888






PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))                                                        PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))



       perl -e "print <Ctrl-x>"Hello world\n<Ctrl-x>""

     Under the Mac, it depends which environment you are using.  The MacPerl
     shell, or MPW, is much like Unix shells in its support for several
     quoting variants, except that it makes free use of the Mac's non-ASCII
     characters as control characters.

     I'm afraid that there is no general solution to all of this.  It is a
     mess, pure and simple.

     [Some of this answer was contributed by Kenneth Albanowski.]

     WWWWhhhheeeerrrreeee ccccaaaannnn IIII lllleeeeaaaarrrrnnnn aaaabbbboooouuuutttt CCCCGGGGIIII oooorrrr WWWWeeeebbbb pppprrrrooooggggrrrraaaammmmmmmmiiiinnnngggg iiiinnnn PPPPeeeerrrrllll????

     For modules, get the CGI or LWP modules from CPAN.  For textbooks, see
     the two especially dedicated to web stuff in the question on books.  For
     problems and questions related to the web, like "Why 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

         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

         Perl/CGI programming FAQ, by Shishir Gundavaram and Tom Christiansen
             http://www.perl.com/perl/faq/perl-cgi-faq.html

         The WWW Security FAQ, by Lincoln Stein
             http://www-genome.wi.mit.edu/WWW/faqs/www-security-faq.html

         World Wide Web FAQ, by Thomas Boutell
             http://www.boutell.com/faq/


     WWWWhhhheeeerrrreeee ccccaaaannnn IIII lllleeeeaaaarrrrnnnn aaaabbbboooouuuutttt oooobbbbjjjjeeeecccctttt----oooorrrriiiieeeennnntttteeeedddd PPPPeeeerrrrllll pppprrrrooooggggrrrraaaammmmmmmmiiiinnnngggg????

     the _p_e_r_l_t_o_o_t manpage is a good place to start, and you can use the
     _p_e_r_l_o_b_j manpage and the _p_e_r_l_b_o_t manpage for reference.  Perltoot didn't
     come out until the 5.004 release, but you can get a copy (in pod, html,
     or postscript) from http://www.perl.com/CPAN/doc/FMTEYEWTK/ .

     WWWWhhhheeeerrrreeee ccccaaaannnn IIII lllleeeeaaaarrrrnnnn aaaabbbboooouuuutttt lllliiiinnnnkkkkiiiinnnngggg CCCC wwwwiiiitttthhhh PPPPeeeerrrrllll???? [[[[hhhh2222xxxxssss,,,, xxxxssssuuuubbbbpppppppp]]]]

     If you want to call C from Perl, start with the _p_e_r_l_x_s_t_u_t manpage, moving
     on to the _p_e_r_l_x_s manpage, the _x_s_u_b_p_p manpage, and the _p_e_r_l_g_u_t_s manpage.
     If you want to call Perl from C, then read the _p_e_r_l_e_m_b_e_d manpage, the
     _p_e_r_l_c_a_l_l manpage, and the _p_e_r_l_g_u_t_s manpage.  Don't forget that you can
     learn a lot from looking at how the authors of existing extension modules
     wrote their code and solved their problems.



                                                                        PPPPaaaaggggeeee 9999






PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))                                                        PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))



     IIII''''vvvveeee rrrreeeeaaaadddd ppppeeeerrrrlllleeeemmmmbbbbeeeedddd,,,, ppppeeeerrrrllllgggguuuuttttssss,,,, eeeettttcccc....,,,, bbbbuuuutttt IIII ccccaaaannnn''''tttt eeeemmmmbbbbeeeedddd ppppeeeerrrrllll iiiinnnn mmmmyyyy CCCC
     pppprrrrooooggggrrrraaaammmm,,,, wwwwhhhhaaaatttt aaaammmm IIII ddddooooiiiinnnngggg wwwwrrrroooonnnngggg????

     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
     the _p_e_r_l_b_u_g manpage and send a bugreport with the output of make test
     TEST_VERBOSE=1 along with perl -V.

     WWWWhhhheeeennnn IIII ttttrrrriiiieeeedddd ttttoooo rrrruuuunnnn mmmmyyyy ssssccccrrrriiiipppptttt,,,, IIII ggggooootttt tttthhhhiiiissss mmmmeeeessssssssaaaaggggeeee.... WWWWhhhhaaaatttt ddddooooeeeessss iiiitttt mmmmeeeeaaaannnn????

     the _p_e_r_l_d_i_a_g manpage has a complete list of perl's error messages and
     warnings, with explanatory text.  You can also use the splain program
     (distributed with perl) to explain the error messages:

         perl program 2>diag.out
         splain [-v] [-p] diag.out

     or change your program to explain the messages for you:

         use diagnostics;

     or

         use diagnostics -verbose;


     WWWWhhhhaaaatttt''''ssss MMMMaaaakkkkeeeeMMMMaaaakkkkeeeerrrr????

     This module (part of the standard perl distribution) is designed to write
     a Makefile for an extension module from a Makefile.PL.  For more
     information, see the _E_x_t_U_t_i_l_s::_M_a_k_e_M_a_k_e_r manpage.

AAAAUUUUTTTTHHHHOOOORRRR AAAANNNNDDDD CCCCOOOOPPPPYYYYRRRRIIIIGGGGHHHHTTTT
     Copyright (c) 1997 Tom Christiansen and Nathan Torkington.  All rights
     reserved.  See the _p_e_r_l_f_a_q manpage for distribution information.




















                                                                       PPPPaaaaggggeeee 11110000






PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))                                                        PPPPEEEERRRRLLLLFFFFAAAAQQQQ3333((((1111))))























































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