LevSelector.com New York
home > Perl
* perl in large corporations
* reference
* Perl is the best
* Perl tutorials
* Perl books
* Perl people
* Larry Talks
* misc
* D.Conway in NY

* perl_examples
* perl_examples_tut


"Any machine 
that doesn't have
perl on it
is a sad machine

Perl in large corporations home - top of the page -

All big businesses use perl. You will be surprised to find out how many well known businesses run their high-traffic sites on Perl. Amazon, Adobe, Macromedia, CitySearch, ValueClick, Morgan Stanley, etc. See some examples:

Perl is a backbone of many production systems in big financial firms (Morgan Stanley, Goldman Sachs, Solomon Smith Barney, Merrill Lynch, Jefferies and Co., Lehman Brothers, Bloomberg - just to name few) and of some biggest online business (Amazon, eToys, etc.). Here are more examples:

- http://www.activestate.com/Products/PerlDirect/ - PerlDirect - Pre-validated, quality-assured Perl for corporations that rely on Perl for high-usage applications.

reference home - top of the page -

* http://www.yapc.org/America/reports.shtml- latest YAPC notes, photos, mp3

* www.perl.com/pub/doc/manual/html/pod/perlfunc/ - alphabetical list of functions
* www.perl.com/pub/doc/manual/html/pod/perlfunc.html - perl functions by category
* www.perldoc.com - perl docs
* www.perldoc.com/cpan/ - modules docs (not all, good formatting).
* www.perldoc.com/perl5.6/lib.html - list of ~ 300 modules for perl 5.6.

CPAN - Comprehensive Perl Archive Network
* http://search.cpan.org/ -
* http://search.cpan.org/Catalog/World_Wide_Web/HTML/ -
To go to a particular module - just put it as a parameter in URL, for example:
* http://search.cpan.org/search?module=HTML::Template - HTML::Template
* http://search.cpan.org/search?module=CGI::Application - CGI::Application

Links to docs for some modules:
-- CGI -- CGI::Application -- CGI::Carp -- HTML::Template -- GD --
-- Getopt::Long -- LWP::Simple -- Bundle::LWP -- NET::FTP -- NET::SMTP -- Net::LDAP -- MIME::Lite -- Socket - IO::Socket - Net::SSLeay -
-- Time::Local -- Date::Calc -- Date::Format --

-- Data::Dumper -- App::Config -- File::Copy -- File::Path -- Fcntl -- POSIX -- Carp -- English -- FindBin -- HTML::Element -- HTML::AsSubs -- Benchmark -- Test -- Test::Harness -- ExtUtils::MakeMaker -- Devel::Coverage -- Devel::DProf -  -  -  - 

 - DBI -DBD::RAM => DBD::AnyData - DBD::mysql - DBD::DB2 - DBD::Oracle - DB_File -
2 ODBC drivers on Windows:  DBD::ODBC - Win32::ODBC  -
Sybase:  DBD::Sybase
- Sybperl - Sybase::Sybperl - ( Sybase::CTlib, Sybase::DBlib, Sybase::BCP
- http://www.peppler.org/ - http://www.mbay.net/~mpeppler/ - sybperl

When docs are not there - just on go Google and type name of the file and word "perldoc", for example: perldoc  Carp.pm
Here are examples of docs found using this approach:
- Carp - Cwd - FileHandle - XML::Simple-XML::Twig - IniConf - File::Basename

LWP library - collection of eight main modules:
  File, Font, HTML, HTTP, LWP, MIME, URI, and WWW

The best way to build your web application:
* CGI::Application module - www.perldoc.com/cpan/CGI/Application.html
* HTML::Template module - www.perldoc.com/cpan/HTML/Template.html

* www.perl.com/pub/v/documentation - documentation
* www.perl.com/CPAN/doc/manual/html/pod/perl.html - main manpage

* http://www.perl.com/reference/query.cgi?tutorials - list of Perl tutorials

* www.perl.com/CPAN/ - CPAN
* www.perl.com/CPAN/doc/FMTEYEWTK/index.html - Far More Than Everything You've Ever Wanted to Know About...
* www.linguistik.uni-erlangen.de/tree/html/perl5/pod/- tutorials and references
* language.perl.com/info/documentation.html -
* www.mit.edu/perl/perl.html -

Documentation on the prompt (both unix or DOS):
  perldoc -
  perldoc -h -
  perldoc perldoc -
  perldoc perlfunc - built-in funcitons
  perldoc -f die - built-in functions by name
  perldoc perlvar -  $_, $@, $|, etc.
  perldoc perlre - regular expressions
  perldoc perl -
  perldoc CGI - CGI.pm by name
  perldoc -q CGI -

Using man command:
   to read documentation: pod2man name.pm | nroff -man | less
   to convert man pages to text: man comname | col -b > out.txt

Some Main Sites home - top of the page -

Why camel?  It's a horse designed by committee.  It's not graceful, it's not pretty, looks like its cobbled together from bits of other animals and if you mistreat it it'll spit in your eye. But camels are surprisingly fast, can carry a heavy load and will happily keep going long after your horse has died. 

The dromedary (Arabian camel, Camelus dromedarius, one hump) and the bactrian (Camelus Bactrianus, native to the cold 
deserts of the Central Asian plateau (Bactria), two humps) are both varieties of camels. I suspect O'Reilly went with the Arabian camel as its the one we're used to seeing and, possibly more important where Larry is concerned, is also the one spoken of in the Bible.- Michael G. Schwern (www.pobox.com/~schwern/)

* www.perl.com - main perl site
* http://dev.perl.org/perl6/ - Perl6 development
* www.perl.org -
* http://use.perl.org - perl news (posings running slash 2 software
* http://www.yetanother.org - Yet Another Society
* http://dbi.symbolstone.org/- subscribe to DBI users mailing list
* http://lists.perl.org/ - The Perl Mailing List Database
* www.tpj.com - http://www.sysadminmag.com/tpj/
* http://perl-foundation.org -
* http://donate.yetanother.org/ -
* http://bio.perl.org/ -

* perl.oreilly.com -
* www.activestate.com - Perl for MS Windows platform
* WAIT - The Great CPAN Search Engine -
* www.perl.com/CPAN-local/modules/INSTALL.html - how to install modules

* www.cs.tu-bs.de/softech/ddd/- debugger

Perl is the Best home - top of the page -
 - Why I Am Not A Java Programmer - by Michael Schwern 
How people like perl:
* www.Lehigh.EDU/~sol0/rules.html

A score below 1.0 means the language sucks.
A score above 1.0 means the language rules.
Darker colors mean a higher number of hits, and therefore a higher degree of certainty about suckiness. - text ofthe script
* srom.zgp.org
* www.jbum.com/jbum/public_opinion.html
* www.tarunz.org/~vassilii/srom/
* www.tarunz.org/~vassilii/srom/srom - text of one version of the script

Perl is taking market share:
Perl is "the glue-language", 
"the duct tape",
"the class of its own".

Tutorials home - top of the page -
* perl_examples -
* tutorial -
* mcse.pair.com/perl_nt.html- Perl for Windows
* CGI Programming 101 by Jacqueline D. Hamilton - Good book to learn Perl and CGI at the same time.
All examples for this book are here:
      * www.cgi101.com/class/ -
      * www.cgi101.com/class/indices.html -

* http://wdvl.internet.com/Authoring/Languages/Perl/PerlfortheWeb/toc.html - tutorial on perl and mod_perl ("The Perl You Need to Know ")

Books home - top of the page -

* Perl 5 by Example by David Medinets. Paperback (October 1996) 
* Programming Perl (3rd Edition) by Larry Wall, et al. Paperback (July 2000) 
* Learning Perl (2nd Edition) by Randal L. Schwartz, et al. Paperback (July 1997) 
* Perl Cookbook by Tom Christiansen, et al. Paperback (August 1998) 
* Effective Perl Programming: Writing Better Programs With Perl by Joseph N. Hall. Paperback (January 1998) 
* Mastering Regular Expressions ... by Jeffrey E. Friedl(Editor), Andy Oram(Editor). Paperback (January 1997) 
   ( read also this online book about regular expressions - by Jeff Pinyan
* Advanced Perl Programming (Nutshell Handbook) by Sriram Srinivasan. Paperback (August 1997)
* CGI Programming 101 by Jacqueline D. Hamilton. Paperback (February 1, 2000) 
* CGI Programming with Perl (2nd Edition) by Scott Guelich, et al. Paperback (July 2000) 
Web Client Programming With Perl 
* Programming the Perl DBI by Alligator Descartes, Tim Bunce. Paperback (February 2000) 
* Perl for System Administration by David N. Blank-Edelman. Paperback (January 15, 2000) 
* Object Oriented Perl by Damian Conway, Randal L. Schwartz(Foreword). Paperback (August 1999) 

* Perl and CGI for the World Wide Web: Visual QuickStart Guide by Elizabeth Castro. Paperback (November 1998) 
* Writing Apache Modules with Perl and C: The Apache API and mod_perl (O'Reilly Nutshell) by Lincoln Stein, et al. Paperback (March 1999) 
* The Perl Cd Bookshelf : 6 Bestselling Books on Cd-Rom by O'Reilly, Inc. Associates(Editor). Software (August 1999)
* Mastering Algorithms With Perl by Jon Orwant, et al. Paperback (August 1999) 
* Official Guide to Programming With Cgi.Pm by Lincoln Stein. Paperback (April 3, 1998) 
* Elements of Programming With Perl by Andrew L. Johnson. Paperback (October 1999) 
* Sams Teach Yourself Perl in 21 Days by Laura Lemay. Paperback (April 1999) 
* Learning Perl on Win32 Systems by Randal L. Schwartz, et al. Paperback (August 1997) 
* Perl 5 Interactive Course with CDROM by Jon Orwant. Paperback (November 1, 1997) 
* Win32 Perl Programming: The Standard Extensions by Dave Roth. Textbook Binding (January 1999)
* Debugging Perl: Troubleshooting for Programmers by Martin C. Brown. Paperback (October 2, 2000) 

Perl people home - top of the page -


Tom Christiansen
Perl Cookbook, 
Learning Perl,
Programming Perl

Randal Shwartz
Programming Perl,
Learning Perl,
Effective Perl Programming,

Gurusamy Sarathy

Jeffrey Friedl
Regular Expressions

Lincoln Stein
CGI.pm, Genome, mod_perl

Jon Orwant
The Perl Journal

Chip Salzenberg
perlsupport.com - Perl 6 (Topaz) in C++

Nathan Torkington,
Perl cookbook

Graham Barr
Net::FTP, IO::Socket. 

Dave Beazley
Swig (Perl/C intergration)

Tim Bunce
DynaLoader, MakeMaker, 
Exporter, DBI, DBD::Oracle,
Oraperl, The Perl Module List. 

Doug MacEachern, 
mod_perl Apache module

Mark-J. Dominus
columnist for tpj.
Sriram Srinivasan
Advanced Perl Programming
Enterprise JavaBeans
Joseph N. Hall

Damian Conway

Dan Sugalski

Simon Cozens

More pictures:
* http://www.oreillynet.com/pub/a/network/2000/06/06/geekcruise.html -
* http://www.supersnail.com/opensource/2index.html -
* http://photo.tomat.dk/tpc4/ -
* http://training.perl.com/instructors.html - TCPC Instructors
* http://www.acedb.org/winfo/Conferences/acedb2000/images/ace03.jpg - Lincoln Stein

* http://conference.oreilly.com/perl3/bios.html
* http://conference.perl.com/cfp.html

Larry Talks home - top of the page -

Larry Wall
Larry Wall introduced Perl (Practical Extraction & Report Language) in 1987.
* kiev.wall.org/~larry/
* www.wall.org
* www.perlmongers.org/press/history.html
* Interview with Larry Wall and Tom Christiansen
* some pictures

List of Larry Walls's talks:
* www.perl.com/pub/au/Wall_Larry

Below are the direct links to these talks:
* www.perl.com/pub/conference/1997/wall/keynote.html -
* www.perl.com/pub/1998/08/show/onion.html -
* www.perl.com/pub/1999/03/pm.html (or http://www.wall.org/~larry/pm.html) -
* www.perl.com/pub/1999/08/onion/talk1.html -
* www.technetcast.com/tnc_program.html?program_id=38 - audio streaming (50 min)
* http://www.perl.com/pub/2000/10/23/soto2000.html?wwwrrr_20001108.txt - State of the Onion 2000
* http://dev.perl.org/~ask/als/larry-als.txt (October 2000) - very goog read (local version)

misc. home - top of the page -

* Perl Shell -
* poe.perl.org - POE
* freshmeat.net/projects/twiki/ -
* TWiki.org/ -
* jobs.perl.org/ - perl jobs
* Joe Johnston

Perhaps also of interest:
* www.unigroup.org - Unigroup is the oldest and largest Unix User's Group in NY City
* www.nysa.org/ -
* groups.yahoo.com/group/perlsemny- Perl Seminars in NY
* ny.pm.org - New York Perl M((o|u)ngers|aniacs)*  (also http://www.netmonger.net/~chris/nypm/ - David Adler et al)
* pw1.netcom.com/~casandra/linux/lugdetails.html - GNU/Linux/OpenSource User Groups in NY

* perl.plover.com/ -
* www.perl.org/phbs/training.html -
* training.perl.com/ TCPC  - (Tom Christiansen Perl Consultancy)
* training.perl.com/courselist.html -
* training.perl.com/instructors.html - (includes MJD)
* www.consultix-inc.com/  - Damian Conway
* www.perltraining.com/  - Joseph N. Hall
* www.stonehenge.com/perltraining/  - Randal L. Schwartz

* www.boutell.com - some interesting stuff

* www.sysarch.com/perl/sort_paper.html - A Fresh Look at Efficient Perl Sorting (Uri Guttman and Larry Rosler)

How to run syntax check on many files at once (Unix):
  \ls  -1  *.pl  |  xargs  -L1  perl  -wc
  find . -name  '*.pl'  -exec perl -wc {} \;

> > perl -e "use Date::Manip;print &UnixDate('today','%Y%m%d%H%M%S');"
> 20030114140958

In perl (as it is in unix) there are references (hard links) and symbolic references (soft links).
In java there are 4 reference types (String (normal), Soft, Weak, Phantom) which differ by the way the can be garbage collected.

 - http://www.perl.com/lpt/a/2001/10/17/etoys.html - success story - architecture of a high-traffic site

Domian Conway in NY home - top of the page -

Lecture July 17, 2001 - here are comments by Jeff "japhy" Pinyan:

His code was called SelfGOL, and did one of four things:
  1. played the game of life:  selfgol -g -x=width -y=height
  2. printed itself as output:  selfgol -s
  3. print a scrolling marquee:  selfgol -d="banner"
  4. modify a program to print itself as output: selfgol progname

It did this in under 1000 bytes of code:
#!/usr/local/bin/perl -sw
if($j){{$^W=$|;*_=sub{$=+s=#([A-z])(.*)#=#$+$1#=g}}     #_The_Perl_Journal_#
q<#!/usr/local/bin/perl -sw
if(!$s){>.($_=<>).q<}else{@s=(q[printf+pop@s,@s],q[#!/usr/local/bin/perl -sw

The code continained no regular control structures (like while, if, unless, until, for) -- it had some goto()s, some recursion, and some beautiful eval-crafted loops:

  $g = '$i=0;
        $i? $b : $c = $b;
        substr +$c, $i, 1, g $i;
        $g =~ s?\d+? ($&+1)%$y ?e;
        $i - $y + 1 ? eval $g
                    : do{ $b=$c; p; i }';

The best part was the self-replicating code, which used the standard quine code:
    q[printf pop@s, @s],
  printf pop @s, @s;

There were some gems of quotes from Damian.  One of them was centered around the $g code above:

"The only thing better than self-modifying code is code that modifies itself before it does so." 

more misc. home - top of the page -

- http://cgi.resourceindex.com/Programs_and_Scripts/Perl/ - collections of perl CGI scripts

About downloading files from web pages.

Depending on the task your program may be very simple.
Here are 2 basic examples:
use LWP::Simple;
$text = get('http://www.someaddress.com');
use LWP::UserAgent;
$ua = LWP::UserAgent->new;
$ua->proxy(['http', 'ftp'] => ‘http://proxy.somedomain.net:8080’);
my $url = 'http://www.somedomain.no/somedir/somefile.tar.gz';
# $url = 'http://www.somedomain.no/somedir/somescript.cgi?par1=val1’;
my $req = HTTP::Request->new(GET => $url);
$res = $ua->request($req, "somefile.tar.gz");

if (! $res->is_success) {
   print "ok\n";
} else {
   print $res->status_line, "\n";
You probably will have to go in 2 steps.
Step 1 – get the page (LWP::UserAgent or LWP::Simple)
Step 2 - parse its HTML to get a list of files (HTML::Parser, HTML::TreeBuilder)
Read this good article - http://www.perl.com/pub/2006/01/19/analyzing_html.html
Step 3 – get the files (LWP::UserAgent)

So beginning of your perl script will probably have:
use LWP::UserAgent;
use HTTP::Request;
use HTTP::Response;
use HTTP::Request::Common;
use Regexp::Common qw(URI);
I recommend you to buy these 2 books (I have both of them). You can buy them “used” on amazon very cheaply.
   Spidering Hacks – by Kevin Hemenway, Tara Calishain (O’Reilly, 2003)
   Perl & LWP – by Sean M. Burke (O’Reilly, 2002)
Also, look at this cook-book page:
It will give you basic examples, including how to download files – and which modules to use.

Main work horse module:
LWP::UserAgent - http://search.cpan.org/~gaas/libwww-perl-5.837/lib/LWP/UserAgent.pm - this is the main work horse

But there are many-many modules which can be used
depending on the task, for example:

LWP::Simple - http://search.cpan.org/~gaas/libwww-perl-5.837/lib/LWP/Simple.pm
LWP::UserAgent - http://search.cpan.org/~gaas/libwww-perl-5.837/lib/LWP/UserAgent.pm - this is the main work horse
WWW::Mechanize - http://search.cpan.org/dist/WWW-Mechanize/lib/WWW/Mechanize.pm

Note – to find modules on cpan, google them with the word ‘cpan’ and substituting ‘::’ by a dash, for example:
cpan http-response
cpan lwp-useragent

Perl one-liners

# substitue one word with another in all files in a directory:
perl -pi -e 's/word/another/g' *

# dos-2-unix as a one-liner:
perl -pi -e 's/\r\n/\n/' myscript.cgi

# stripping the font tags:
perl -0777 -pi -e 's/<\/?FONT[^>]*>//gi' filename

# list CLASSPATH entries on separate lines (originally they are ":"-separated):
echo $CLASSPATH | perl -e '$_=<>;s/:/\n/g;print;'

# make a nice listing of files (use ls, find, grep to lacate files):
ls *.java | perl -nle '$n=$_;$h="-"x60 . "\n";print "$h$n\n$h"; open(in,$n); map {chomp;print}<in>;' > ~/java.txt
ls *.xsl | perl -ne '$n=$_;$h="-"x60 . "\n";print "$h$n$h"; open(in,$n); map {print}<in>;' > ~/xsl.txt
ls *.java | perl -nle '$n=$_;$h="-"x60 . "\n";{local $/=undef;open(in,$n);$s=<in>;}print "$h$n\n$h$s\n";' > ~/java.txt
perl -e '$h="-"x60 . "\n";for $n (<*.java>){{local $/=undef;open(in,$n);$s=<in>;}print "$h$n\n$h$s\n";}' > ~/ttt.txt


#! /usr/local/bin/perl
map{open(IN,$_);print "-"x60 ."\n$_\n"."-"x60 ."\n";map{print}<IN>;close(IN);}glob("*.java");

#! /usr/local/bin/perl
$h="-"x60 . "\n";for $n (<*.java>){local $/=undef;open(IN,$n);$s=<IN>;print "$h$n\n$h$s\n";}

#! /usr/local/bin/perl
# getall.pl
# usage: ls -1 * | xargs getall.pl > out.txt
map{open(IN,$_);print "-"x60 ."\n$_\n"."-"x60 ."\n";map{print}<IN>;close(IN);} @ARGV;

# rename many files simultaneously (here it renames *.tar into *.tar7):
ls -1 *.tar | perl -nle '$old=$_;s/(\.+)tar/$1tar7/;rename($old, $_);' -

# print help for all commands of perforce (p4) source control system:
p4 help commands | perl -nle 'm/^\s+(\w+)\s/; print "$1\n";' - | xargs p4 help

# sum first and last fields (using -a option to split input into @F):
perl -lane 'print $F[0] + $F[-1]' *

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

# remove (most) 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 (072 is code of ":"):
echo $PATH | perl -nl -072 -e 's![^/+]*$!man!&&-d&&!$s{$_}++&&push@m,$_;END{print"@m"}'

# Print a message if a daylight savings time change occurs within the next 5 days:
print "\aTIME CHANGE COMING!\n" if (localtime(time))[8] ne (localtime(time+5*24*60*60))[8];

perl -e 'print "$_\n" for @INC'