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The Perl Presentation - also talks about writing simple TWiki Plugin
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Perl Presentation
- 1. Perl Sopan Shewale, [email_address]
- 2. Hello World – First Program $ cat HelloWorld.pl #!/usr/bin/perl print "Welcome to the world of Perl Programming !"; $ chmod +x HelloWorld.pl $ ./HelloWorld.pl Welcome to the world of Perl Programming ! $ perl HelloWorld.pl Welcome to the world of Perl Programming ! Make it executable Execute it Another Way to Execute
- 3. Another Simple Example – Taking input from user [sopan@ps3724 tutorial]$ cat InteractiveHello.pl #!/usr/bin/perl my $user; print "Please write your name:"; $user = <STDIN>; print "Welcome to the world of perl, You are : $user";
- 4. Simple example – way to execute external command [sopan@ps3724 tutorial]$ cat df.pl #!/usr/bin/perl print "Method1:"; my $out1 = system("df -k"); print "The output of df -k command is : $out1"; Method1: Filesystem 1K-blocks Used Available Use% Mounted on /dev/hda8 19346964 10931664 7432528 60% / /dev/hda1 101089 14826 81044 16% /boot /dev/hda3 15116868 12328832 2020132 86% /home none 252056 0 252056 0% /dev/shm /dev/hda5 8064272 5384612 2270008 71% /usr /dev/hda6 3020140 307088 2559636 11% /var /dev/hda2 30233928 8830792 19867324 31% /usr/local The output of df -k command is : 0
- 5. Simple example – way to execute external command print "Method2:"; my $out2 = `df -k`; print "The output of df -k command is : $out2"; Method2: The output of df -k command is : Filesystem 1K-blocks Used Available Use% Mounted on /dev/hda8 19346964 10931664 7432528 60% / /dev/hda1 101089 14826 81044 16% /boot /dev/hda3 15116868 12328832 2020132 86% /home none 252056 0 252056 0% /dev/shm /dev/hda5 8064272 5384612 2270008 71% /usr /dev/hda6 3020140 307088 2559636 11% /var /dev/hda2 30233928 8830792 19867324 31% /usr/local [sopan@ps3724 tutorial]$
- 14. Regular expression (Cont…) Let us look at the example if ("Hello World " =~ /World/) { print "It matches"; } else { print "It doesn't match"; } The sense of =~ is reversed by !~ operator.
- 15. Regular Expression (Cont…) The literal string in the regexp can be replaced by a variable: $greeting = "World"; if ("Hello World" =~ /$greeting/) { print "It matches"; } else { print "It doesn't match"; } Regexp’s are case sensitive
- 23. [1]. Start with the first letter in the string 'a'. [2]. Try the first alternative in the first group 'abd'. [3]. Match 'a' followed by 'b'. So far so good. [4]. 'd' in the regexp doesn't match 'c' in the string – a dead end. So backtrack two characters and pick the second alternative in the first group 'abc'. [5]. Match 'a' followed by 'b' followed by 'c'. We are on a roll and have satisfied the first group. Set $1 to 'abc'. [6]. Move on to the second group and pick the first alternative 'df'. [7]. Match the 'd'. [8]. 'f' in the regexp doesn't match 'e' in the string, so a dead end. Backtrack one character and pick the second alternative in the second group 'd'. [9]. 'd' matches. The second grouping is satisfied, so set $2 to 'd'. [10]. We are at the end of the regexp, so we are done! We have matched 'abcd' out of the string "abcde". Regular Expression (Cont…)
- 33. References # Create some variables $a = "mama mia"; @array = (10, 20); %hash = ("laurel" => "hardy", "nick" => "nora"); # Now create references to them $ra = a; # $ra now "refers" to (points to) $a $rarray = array; $rhash = hash; #You can create references to constant scalars in a similar fashion: $ra = 0; $rs = amp;quot;hello world";
- 45. Example: Count Click Script #!/usr/bin/perl ######################### ## Author: Sopan Shewale ## Company: Persistent Systems Pvt Ltd ## This script is created for giving demo on click count. ## The Script is support to display increse/decrease ##click's, handles back button of browser, does not ##handle reload stuff. ## also it's based on sessions. ######################## use strict; use warnings; use CGI; use CGI::Session; use CGI::Cookie; my $q = new CGI(); my $sessionid = $q->cookie("CGISESSID") || undef; my $session = new CGI::Session(undef, $sessionid, {Directory=>'/tmp'}); $sessionid = $session->id(); my $cookie = new CGI::Cookie(-name=>'CGISESSID', -value=>$sessionid, -path=>"/"); print $q->header('text/html', -cookie=>$cookie); print $q->start_html("Welcome to Click Count Demo"); print "<h1>Welcome to Click Count Demo</h1>"; my $count = $session->param('count'); ## count-is click count variable if(!defined($count)) { $session->param('count', 0); $count=0;} ### if session is first time created, set count=0 $session->param('count', $count); $count = $session->param('count'); #print "<h1>The Click Count is: $count "; ## Form stuff print $q->startform(-method=>'POST'); print $q->submit( -name=>"Increase", -value=>'Increase1'); print $q->submit( -name=>"Decrease", -value=>'Decrease1'); print $q->endform();
- 46. Example: Count Click Script (Cont…) ## Which button is being pressed my $which_button = $q->param('Increase'); if(defined ($which_button)) { print "Increase pressed"; $count = increase_count($count); ## Increase the count since increase button is clicked $session->param('count', $count); }else { $which_button=$q->param('Decrease'); if(defined($which_button)){ print "Decrease pressed"; $count = decrease_count($count); ## Decrease the count since decrease button is clicked $session->param('count', $count); } else {print "You have not pressed any button, seems you are typing/re-typing the same URL"; } } $count = $session->param('count'); print "<h1>The Click Count is: $count "; print $q->end_html(); ## increases the count by 1 sub increase_count { my $number = shift; $number = $number +1; return $number; } ## decreases the count by 1 sub decrease_count { my $number = shift; $number = $number -1; return $number; }
- 48. Data::Dumper
- 49. TWiki
- 50. bin: view, edit, search etc tools: mailnotify template: Templates (view.tmpl), also has skin related data lib: modules and required libraries, plugin code data: webs directories (e.g. Main,TWiki) and each directory inside contains the topics from that web. The topics are companied by there version history pub: Attachments of the topics and commonly shared data