Perl Cheat Sheet

#Perl Cheat Sheet 

# INSTALLING MODULES ON PERL 

perl -e -MCPAN "install 'GD'" 

ppm search module:name

#READ ALL ROWS OF A FILE TO ALIST 

open (INPUT, "<$inputfile") || print "could not open the file!\n"; 

@myfile = <INPUT>;

close INPUT;

#FOREACH LINE OF THE FILE DO SOMETHING

foreach my $line ( @lineArray  ) 

{

print "$line" ; 

} #eof foreach 

# END FOREACH LINE 

#GET A NICE TIME 

sub timestamp {

#

# Purpose: returns the time in yyyymmdd-format 

#

my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time); 

#---- change 'month'- and 'year'-values to correct format ---- 

$min = "0$min" if ($min < 10); 

$hour = "0$hour" if ($hour < 10);

$mon = $mon + 1;

$mon = "0$mon" if ($mon < 10); 

$year = $year + 1900;

$mday = "0$mday" if ($mday < 10); 

return "$year$mon$mday" . "_" . "$hour$min" . "_" . $sec; 

}

# READ ALL ROWS TO LIST

open (FILE,$file);

@rows = <FILE>;

close (FILE);

# GREP ALL ROWS CONTAINING 'MACHINE=' (TO A LIST)

@list = grep(/machine=/,@rows); 

# A NICE WAY TO CONCATENATE A STRING TO THE SAME STRING 

#--- Collect agents from yesterday ------------------------------

$sql = "select distinct(AgentName),LocationName from TransactionDetails td "; 

$sql .= "inner join Applications ap on td.ApplicationID = ap.ApplicationID ";

$sql .= "inner join Agents ag on td.AgentID = ag.AgentID ";

$sql .= "inner join Locations lo on td.LocationID = lo.LocationID ";

$sql .= "where ApplicationName like \'" . $APPLICATION . "\' and "; 

$sql .= "StartTime between \'" . $DAY2 . "\' and \'" . $DAY1 . "\' "; 

$sql .= "order by 1";

# THE EQUIVALENT OF THE SET COMMAND TROUGH THE COMMAND PROMT 

foreach $i (keys %ENV) 

{

print FH "$i : $ENV{$i} \n";

}

#accept a command line parameter 

our $CycleScriptRun_pid = $ARGV[0] ; 

#========================================================== 

#start a Windows process 

use Win32 ; 

use Win32::Process ; 

my $DayCycle_path= $varHolder->{'BASEDIR'} . " DayCycle.exe" ;

if( $varHolder->{VISIBLE_MODE} == 1)

{ Win32::Process::Create( $DayCycle_o, "$DayCycle_path", "" , 0, 

CREATE_NEW_CONSOLE ,$varHolder->{'BASEDIR'}); } 

else

{ Win32::Process::Create( $DayCycle_o, "$DayCycle_path", "" , 0,

CREATE_NO_WINDOW ,$varHolder->{'BASEDIR'}); } 

$DayCycle_pid = $DayCycle_o->GetProcessID() ; 

#========================================================== 

#==========================================================

#Purpose : to tie a file 

#============================= =============================

use Tie::File ; 

my @file_array = ();

my $file = 'C:/Temp/folder/settings.txt' ; 

tie @file_array , 'Tie::File', $file , memory => 100_000_000 or die "I cannot find the $file" ; 

foreach (@file_array) #foreach line of the file 

{ s/$setting=(\d+)/$setting=$value/; 

}

untie @file_array ; 

#==========================================================

#========================================================== 

# create a nameless hash

#========================================================== 

my $record = #one record for each cycle 

{

APP=> "$csAppName" , 

SCRIPT=> "$psCurrentScript" , 

STEP=> "$psCurrentStep" 

} ;

#========================================================== 

#========================================================== 

#simple  perl regex cheatsheet

#========================================================== 

Operators

m// 'Match' operator

s/// 'Substitute' operator 

tr/// 'Translate' operator 

# Special Characters

. Any single character escept newline n

b Between word and non-word chars, ie: /bcat/b/ matches "cat" but not "scat" 

B NOT between word and non-word chars 

w Word character 

W Non-word character

d Digit

D Non-digit

s White-space

S Non-white-space

# Assertions (Position Definers)

^ Start of the string

$ End of the string

# Quantifiers (Numbers Of Characters) 

n* Zero or more of 'n'

n+ One or more of 'n'

n? A possible 'n'

n{2} Exactly 2 of 'n'

n{2, } At least 2 (or more) of 'n' 

n{2,4} From 2 to 4 of 'n'

# Groupings

() Parenthesis to group expressions

(n/sitebuilder/regex/images/1/a) Either 'n' or 'a'

Character Classes

[1-6] A number between 1 and 6 

[c-h] A lower case character between c and h 

[D-M] An upper case character between D and M

[^a-z] Absence of lower case character between a and z

[_a-zA-Z] An underscore or any letter of the alphabet

Useful  Perl  Snippets

$mystring =~ s/^s*(.*?)s*$/$1/; Trim leading and trailing whitespace from $mystring 

$mystring =~ tr/A-Z/a-z/; Convert $mystring to all lower case

$mystring =~ tr/a-z/A-Z/; Convert $mystring to all upper case 

tr/a-zA-Z//s; Compress character runs, eg: bookkeeper -> bokeper

tr/a-zA-Z/ /cs; Convert non-alpha characters to a single space 

#=============================================================

#Install a perl module from behind a firewalll using ppm

#=============================================================

Example with Compress-Bzip2 

1. Download tar package from the nearest cpan mirror to C:\Temp\TEMP folder (could be other also ; ) 

2. Create Compress-Bzip2.ppd type of file , containging the following: 

<?xml version="1.0" encoding="UTF-8"?> 

<SOFTPKG NAME="Compress-Bzip2" VERSION="2,2,09"> 

<TITLE>Compress-Bzip2</TITLE>

<ABSTRACT>Blah</ABSTRACT>

<AUTHOR>Somebody</AUTHOR>

<IMPLEMENTATION> 

<CODEBASE HREF="file:///C|/Temp/TEMP/Compress-Bzip2-2.09.tar.gz "></CODEBASE>

<INSTALL></INSTALL>

<UNINSTALL></UNINSTALL>

</IMPLEMENTATION>

</SOFTPKG> 

Attention: . Name and codebase NOT C:\ BUT file:///C|

3. Open Dos prompt into the C:\Temp\TEMP (or whichever you prevered in the beginning) 

4. Run the command : 

ppm rep add downloadedTars C:\Temp\A_DOWNLOADS\downloaded _perlmodules 

In order to add the folder to the list of your current ppm repositories 

5. ppm install Compress-Bzip2

In order to install the module from the local folder 

6. ppm rep delete myNewRepository 

In order to remove the repository from the ppm 

#Add Nokia's servers to thte local ppm's repository 

ppm rep add linox1 http://linox.nokia.com/mirror/cpan/

ppm rep add linox2  ftp://linux.nokia.com/mirror/cpan/

#sleep for less than second in Windows 

use Win32 ; 

Win32::sleep ($time_in_milliseconds);

#=================================================================== 

#throw proper errro messages while checking the file size 

use File::stat qw(:FIELDS);

#create the obj wrapper for getting the file attributes 

my $st =stat($file) or croak ( "No $stdout : $!"); #die will shut down the program !!!! 

# get the file size 

my $size = $st->size();

$stat_obj =stat($stdout) or die "No $stdout: $!";

#throw proper errro messages ^^^^

($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,

$atime,$mtime,$ctime,$blksize,$blocks) 

= stat($filename);

#===================================================================

#================================================================

#get the computername of a computer 

$computername = $ENV{COMPUTERNAME} ; 

#get the username of the a Windows computer

$userName = $ENV{USERNAME} ; 

#get the name of the currrent executing script and ints pid 

print $0 , $$ ; 

#=========================================================== ======== 

#The textpad settings for jump to error for perl scripts File 1 Register 2

^.+at (.+) line ([0-9]+)[.,]?

exec *.pl *.pm *.cgi /s /b do  perl -wc 

#=========================================================== ===== 

#===================================================================

#======== Exctract only the name of a file witout the long path 

#=================================================================== 

my ($keijo) = "c:\\homo\\urpo\\neste\\kekvo.exe";

@homo = split(/\\/,$keijo);

$jee = pop(@homo);

#The same thing 

$file=~m/^.*(\\|\/)(.*)/; # strip the remote path and keep the filename

my $name = $2; 

#===================================================================

#=================================================================== 

#PRINT TILL THE END OF A LABLE 

#============================= ====================================== 

print <<END_HTML;

<html> <head> 

<title>thanks!</title> 

</head> 

<body> 

<p>thanks for uploading your photo!</p> 

<p>your photo:</p> 

<img src="/upload/$filename" border="0"> 

</body> </html> 

END_HTML

# IMPORTANT !!!! IF THERE ARE SPACES IN THE PREVIOUS LINE == SYNTAX ERROR 

#=================================================================== 

#check for file existance and other attributes 

$readfile="myfile.cgi";

if ( (-e $readfile) && (-r $readfile) ) 

{ 

#proceed with your code

}

#================================================================= 

#how to check my perl installed modules

#perldoc perllocal OR 

#ppm install ExtUtils::Installed save and run this one 

#source  http://www.cpan.org/misc/cpan-faq.html#How_installed_modules 

use ExtUtils::Installed;

my $instmod = ExtUtils::Installed->new();

foreach my $module ($instmod->modules()) 

{

my $version = $instmod->version($module) || "???"; 

print "$module -- $version\n"; 

}

#=================================================================

#How to check version of a module on Windows XP

perl  -le "use CGI; print $CGI::VERSION"

#change the @INC withing a perl script 

#Is Mail::Sendmail installed correctly? (Can you run a script with just "use Mail::Sendmail;"?) Check your @INC on your web server, and copy Sendmail.pm to a Mail subdirectory of one of the dirs. in your @INC. If you have not access to any of these, add the directory in a BEGIN block: 

#BEGIN{ unshift @INC, '/absolute/path/to/my/personal/perl_lib'; } and copy Sendmail.pm to /absolute/path/to/my/personal/perl_lib/Mail/Sendmail.pm. 

local( $/, *FILE ) ; 

open (FILE , $sessionFile ) or 

die "Cannot find $sessionFile !!! " ; 

$fileString = <FILE>; #slurp the whole file into one string !!! 

close FILE ; 

use Encode ; 

my $fileByteStream = decode('windows-1251', $fileString );

my $UTFSream = encode('UTF-8', $fileByteStream);

print "Read the whole directory for specific types of files " ; 

$dh = DirHandle->new($path) or die "Can't open $path : $!\n";

@files = grep { /\.[ch]$/i } $dh->read();

# START FOREACH LINE 

#SET HERE THE PATH TO THE FILE 

my $inputfile='DD61_STG_OMDW.vwFactUserRegistration.txt' ; 

#READ ALL ROWS OF A FILE TO ALIST 

open (INPUT, "<$inputfile") || print "could not open the file!\n"; 

my @lineArray = <INPUT>;

close INPUT;

#how-to print key values in hashes 

while( my ($key, $value) = each %$refHash) 

{

print "\n key: $key, value: $value.\n";

}

#<<DOC_END;

The purpose of the script is ... 

DOC_END