1. for (;;) {
   2.    undef $!;
   3.    unless (defined( $line = <> )) {
   4.        last if eof;
   5.        die $! if $!;
   6.    }
   7.    # ...
   8. }

##</code><code>##

#!/usr/bin/perl -w
use strict;

my $SessionID = $ARGV[0];

# my $infile="\\\\10.0.16.97\\c\$\\web\\Apache-SSL\\logs\\access.log";
my $infile="Input\\access.log"; 
my $outfile="Output\\$SessionID\.html"; 
my $plogfile="Output\\$SessionID\-participants-log.html";
my $ologfile="Output\\$SessionID\-observers-log\.html";

my $line;
my ($logtime,$starttime,$endtime,$timecheck);
my ($FullURL,$ObURL);
my ($UserID,$ObserverID);
my (@Participants,@Observers);

sub TranslateURL; # Changes all URL Escape Codes to regular charecters
sub GetUserID; # Gets UserID from FullURL
sub GetObserverID; # Gets ObserverID from ObURL
sub AddToUserArray; # Checks if this is a new user and adds to user array
sub AddToObserverArray; # Checks if this is a new observer and adds to observer array
sub AddToUserLog; # Adds a line to the user log with the userid, URL and time.
sub AddToObserverLog; # Adds a line to the observer log with the observerid, URL and time.
sub ShowupSummary;

####################
#Beginning of script
####################

$starttime=localtime();
print "Script starting at $starttime\n";
open(IN,"<","$infile") || die "Can't open input file $infile"; 
$timecheck=localtime();
print "Finished open log file at $timecheck\n";
open(PLOG,">","$plogfile") || die "Can't open participants log file $plogfile";
print PLOG "\<html\>\n\<head\>\n\<STYLE TYPE\=\"text\/css\"\>\n\<\!\-\-\nTD\{text\-align\: center\; font\-family\: Arial\; color\: \#FFFFFF\; font\-size\: 10pt\;\}\nTH\{font\-family\: Arial\; font\-size\: 10pt\; background\-color\: \#99CCFF\;\}\n\-\-\-\>\n\<\/STYLE\>\n\<\/head\>\<body\>\n\<center\>\<font face\=Arial\>\n\<table background\=\"images\/bluegradient\.jpg\" border\=1 cellspacing\=0 cellpadding\=5\>\<tr\>\n\<th\>User ID\<\/th\>\n\<th\>URL\<\/th\>\n\<th\>Time\<\/th\>\n\<\/tr\>\n";
close PLOG;
open(OLOG,">","$ologfile") || die "Can't open file $ologfile";
print OLOG "\<html\>\n\<head\>\n\<STYLE TYPE\=\"text\/css\"\>\n\<\!\-\-\nTD\{text\-align\: center\; font\-family\: Arial\; color\: \#FFFFFF\; font\-size\: 10pt\;\}\nTH\{font\-family\: Arial\; font\-size\: 10pt\; background\-color\: \#99CCFF\;\}\n\-\-\-\>\n\<\/STYLE\>\n\<\/head\>\<body\>\n\<center\>\<font face\=Arial\>\n\<table background\=\"images\/bluegradient\.jpg\" border\=1 cellspacing\=0 cellpadding\=5\>\<tr\>\n\<th\>User ID\<\/th\>\n\<th\>Time\<\/th\>\n\<\/tr\>\n";
close OLOG;
open(OUT,">","$outfile") || die "Can't open file $outfile";
print OUT "\<html\>\n\<head\>\n\<STYLE TYPE\=\"text\/css\"\>\n\<\!\-\-\nTD\{text\-align\: center\; font\-family\: Arial\; color\: \#FFFFFF\;\}\nTH\{font\-family\: Arial\; color\: \#FFFFFF\;\}\n\-\-\-\>\n\<\/STYLE\>\n\<\/head\>\<body\>\n\<center\>\<font face\=Arial\>\n\<table background\=\"images\/bluegradient\.jpg\" border\=1 cellspacing\=0 cellpadding\=5\>\<tr\>\n\<th\>No data to display yet\<\/th\>\n\<\/tr\>\n";
close OUT;

print "$!\n";
system('pause');
$line=<IN>;
print "$!\n";
system('pause');
while ($line) {
   #Rest of script...