hi all
i am a java devoloper need to understand a perl scrip based on a project requirement. as i dont know any thing about the Perl i am posting my script here. some body please look in to it and help me out explaing what the script does
the script follows

#!/usr/bin/perl
#
# This program is called in an Analytics/Sector directory to create
# the Deal run time analytsics files within that sector.
# The script must be called with the proper directory, sector and product as arguments.
#

use warnings;
use strict;
use POSIX qw(strftime);


#
# Test to make sure the script is called with correct arguments.
#

($#ARGV == 0) || die "ERROR: Call with one argument: Input Directory \n";

#
# Define local variables.
#

my $InputDir = $ARGV[0]; 
my $FileNamePattern = $InputDir . "/*.txt";		# Pattern to match for input files.
my @FileNames;						# 
my $FileName;						#
my $FileNameFlag;					#
my $Count;						#
my $DistribYearMonth;					#
my $Header;						# Header line of the input file.
my $Line;						# Non-header line from the input file.
my @LineArray;						# Non-header line from the input file.
my $OutLine;						# Output line.
my $DealName;						# Deal name, used to create the output directory.
my @DealNameDirs;					# List of deal name directories.
my $OutFileName;					# Output file name.
my $OutHeader;						# 
my $HeaderValue;
my @HeaderArray;
my %HeaderHash=();
my $now = strftime("%Y-%m-%d %R", localtime(time));
 
#
# Set up the output header.
#

	$OutHeader=	"LoanID" . "\t" . 
			"FICO" . "\t" . 
			"Occupancy" . "\t" .
			"Purpose" . "\t" .
			"Documentation" . "\t" .
			"SFUnit" . "\t" .
			"OrigRate" . "\t" . 
			"CurrRate" . "\t" .
			"Margin" . "\t" .
			"OrigLTV" . "\t" .
			"CombLTV" . "\t" .
			"OrigBalance" . "\t" .
			"CurrBalance" . "\t" .
			"FirstReset" . "\t" .
			"IOTerm" . "\t" .
			"PPTerm" . "\t" .
			"DTI" . "\t" .
			"LoanAge" . "\t" .
			"Lien" . "\t" .
			"PMILevel" . "\t" .
			"ZipCode" . "\t" .
			"StateBucket" . "\t" .
			"PayStatus" . "\t" .
			"PayHistory" . "\t" .
			"Term" . "\t" .
			"AmTerm" . "\t" .
			"LoanNo" . "\n";

#
# Get a list of current deal name directories.
#

@DealNameDirs = glob "*";

foreach $DealName ( @DealNameDirs ){
	chdir($DealName);
	@FileNames = glob("*.txt");
	foreach $FileName ( @FileNames ){
		$FileNameFlag = $FileName . ".flag";
		open(FlagHANDLE,">$FileNameFlag");
		close(FlagHANDLE);
	}
	@FileNames = glob("*.old");
	foreach $FileName ( @FileNames ){
		unlink($FileName);
	}
	chdir("../.");
}

#
# For each .txt file in the New data directory, process the file.
#

@FileNames = glob $FileNamePattern;

foreach $FileName ( sort alphabetically @FileNames ){
print("$FileName \n");
	open(InputHANDLE,$FileName) || die "Could not open $FileName";
	# Get and process the header information
	$Header=<InputHANDLE>;
	chop($Header);
	@HeaderArray=split(/\t/,$Header);
	$Count=0;
	foreach $HeaderValue (@HeaderArray){
		$HeaderHash{$HeaderValue}=$Count;
		$Count++;
	}

	# For each non-header line, process the data.
	while ($Line = <InputHANDLE>) {
		# Grab the deal name and distrib year month fields for this line.
		chop($Line);
		@LineArray=split(/\t/,$Line);
		$DealName=$LineArray[$HeaderHash{'Deal Name'}];
		$DistribYearMonth=$LineArray[$HeaderHash{'Distrib Year Month'}];
		# If the deal name directory does not exist, create it.
		(-d $DealName) || mkdir($DealName,0755);
		# Create the output file name.
		$OutFileName=$DealName . "/" . "DataRT" . $DistribYearMonth . ".txt";
		# If the file name flag is set, move the old run-time file and delete the flag file.
		$FileNameFlag = $OutFileName . ".flag";
		if(-e $FileNameFlag){
			unlink($FileNameFlag);
			rename($OutFileName,$OutFileName . ".old");
		}


		# If the run-time file does not exist, create it and write header line.
		if(!(-e $OutFileName)){ 
			open(OutputHANDLE,">$OutFileName");
			print OutputHANDLE "<HEAD>\n";
			print OutputHANDLE "Version\t1.2\n";
			print OutputHANDLE "Deal\t" . $DealName . "\n";
			print OutputHANDLE "As Of\t" . $DistribYearMonth . "\n";
			print OutputHANDLE "<LOG>\n";
			print OutputHANDLE "Created\tCreator\n";
			print OutputHANDLE $now . "\tPaul Check\n";
			print OutputHANDLE "</LOG>\n";
			print OutputHANDLE $OutHeader;
			print OutputHANDLE "</HEAD>\n";
			close(OutputHANDLE);
		}


		$OutLine=	$LineArray[$HeaderHash{'Numeric Loan ID'}] . "\t" . 
		$LineArray[$HeaderHash{'FICO'}] . "\t" . 
		$LineArray[$HeaderHash{'Occupancy'}] . "\t" . 
		$LineArray[$HeaderHash{'Purpose'}] . "\t" . 
		$LineArray[$HeaderHash{'Document'}] . "\t" . 
		$LineArray[$HeaderHash{'SFUnit'}] . "\t" . 
		$LineArray[$HeaderHash{'Init Coupon'}] . "\t" . 
		$LineArray[$HeaderHash{'Curr Coupon'}] . "\t" . 
		$LineArray[$HeaderHash{'Margin'}] . "\t" . 
		$LineArray[$HeaderHash{'LTV'}] . "\t" .
		$LineArray[$HeaderHash{'Comb LTV'}] . "\t" .
		$LineArray[$HeaderHash{'Orig Amt'}] . "\t" .
		$LineArray[$HeaderHash{'Balance'}] . "\t" .
		$LineArray[$HeaderHash{'Reset Month'}] . "\t" .
		$LineArray[$HeaderHash{'IO Term'}] . "\t" .
		$LineArray[$HeaderHash{'PP Term'}] . "\t" .
		$LineArray[$HeaderHash{'DTI'}] . "\t" .
		$LineArray[$HeaderHash{'Loan Age'}] . "\t" .
		$LineArray[$HeaderHash{'Lien'}] . "\t" .
		$LineArray[$HeaderHash{'PMI Level'}] . "\t" .
		$LineArray[$HeaderHash{'ZipCode'}] . "\t" .
		$LineArray[$HeaderHash{'State Bucket'}] . "\t" .
		$LineArray[$HeaderHash{'Delinq Stat'}] . "\t" .
		$LineArray[$HeaderHash{'Pay History'}] . "\t" .
		$LineArray[$HeaderHash{'Term'}] . "\t" .
		$LineArray[$HeaderHash{'Amort Term'}] . "\t" .
		$LineArray[$HeaderHash{'Loan No'}] . "\n";

		open(OutputHANDLE,">>$OutFileName");
		print OutputHANDLE $OutLine;
		close(OutputHANDLE);
	}
	close(InputHANDLE);
}
 
#
# Delete the flag files.
#

foreach $DealName ( @DealNameDirs ){
	chdir($DealName);
	@FileNames = glob("*.txt.flag");
	foreach $FileName ( @FileNames ){
		unlink($FileName);
	}
	chdir("../.");
}

#
# Subroutine to compare alphbetically, used in sorting.
#

sub alphabetically {
  my ($aa, $bb) = ($a, $b);
  $aa =~ tr/A-Z/a-z/;
  $bb =~ tr/A-Z/a-z/;
  return $aa cmp $bb;
}

thanks and regards
R

atleast pls tell me dii between

my @FileNames;						# 
my $FileName;

i know they are vector and scalar
i need what difference between vector and scalar
and the way we use those variables

vector -> multiple values (i.e. array, which this one is)
scalar -> a single value.

Read the tutorials laready linked to!

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