Shell Programming and Scripting

##!/usr/bin/perl
# file_compare.pl
# Purpose: compare two files and show differences
# usage: file_compare.pl filename1 filename2
use strict;
use warnings;
my $file1 =
  'C:\Documents and Settings\dinesh.lohan\Desktop\comparing_file\file1.txt';
my $file2 =
  'C:\Documents and Settings\dinesh.lohan\Desktop\comparing_file\file2.txt';
open( FILE1, "< $file1" ) or die "Can not read file $file1: $! \n";
my @file1_contents = <FILE1>;    # read entire contents of file
close(FILE1);
open( FILE2, "< $file2" ) or die "Can not read file $file2: $! \n";
my @file2_contents = <FILE2>;    # read entire contents of file
close(FILE2);
my $length1 = $#file1_contents;    # number of lines in first file
my $length2 = $#file2_contents;    # number of lines in second file

if ( $length1 > $length2 ) {

    # first file contains more lines than second file
    my $counter2 = 0;
    foreach my $line_file1 (@file1_contents) {
        chomp($line_file1);
        if ( defined( $file2_contents[$counter2] ) ) {

            # line exists in second file
            chomp( my $line_file2 = $file2_contents[$counter2] );
            if ( $line_file1 ne $line_file2 ) {
                print "\nline " . ( $counter2 + 1 ) . " \n";
                print "< $line_file1 \n" if ( $line_file1 ne "" );
                print "--- \n";
                print "> $line_file2 \n\n" if ( $line_file2 ne "" );
            }
        }
        else {

            # there is no line in second file
            print "\nline " . ( $counter2 + 1 ) . " \n";
            print "< $line_file1 \n" if ( $line_file1 ne "" );
            print "--- \n";
            print "> \n";    # this line does not exist in file2
        }
        $counter2++;         # point to the next line in file2
    }
}
else {

    # second file contains more lines than first file
    # or both have equal number of lines
    my $counter1 = 0;
    foreach my $line_file2 (@file2_contents) {
        chomp($line_file2);
        if ( defined( $file1_contents[$counter1] ) ) {

            # line exists in first file
            chomp( my $line_file1 = $file1_contents[$counter1] );
            if ( $line_file1 ne $line_file2 ) {
                print "\nline " . ( $counter1 + 1 ) . " \n";
                print "< $line_file1 \n" if ( $line_file1 ne "" );
                print "--- \n";
                print "> $line_file2 \n" if ( $line_file2 ne "" );
            }
        }
        else {

            # there is no line in first file
            print "\nline " . ( $counter1 + 1 ) . " \n";
            print "< \n";    # this line does not exist in file1
            print "--- \n";
            print "> $line_file2 \n" if ( $line_file2 ne "" );
        }
        $counter1++;         # point to next line in file1
    }
}

#!/usr/bin/perl -W
use strict;
use warnings; 
my $f1 = 'C:\Documents and Settings\dinesh.lohan\Desktop\comparing_file\2.txt';
my $f2 = 'C:\Documents and Settings\dinesh.lohan\Desktop\comparing_file\a.txt';
my $outfile = 'C:\Documents and Settings\dinesh.lohan\Desktop\comparing_file\1.txt';
my %results = (); 
open FILE1, "$f1" or die "Could not open file: $! \n";
while(my $line = <FILE1>){   $results{$line}=1;
}
close(FILE1); 
open FILE2, "$f2" or die "Could not open file: $! \n";
while(my $line =<FILE2>) {  
 $results{$line}++;
}
close(FILE2);  
open (OUTFILE, ">$outfile") or die "Cannot open $outfile for writing \n";
foreach my $line (keys %results) { print OUTFILE $line if $results{$line} == 1;
}
close OUTFILE;

#!/usr/bin/perl -W
use strict;
use warnings; 
my $f1 = 'C:\Documents and Settings\dinesh.lohan\Desktop\comparing_file\2.txt';
my $f2 = 'C:\Documents and Settings\dinesh.lohan\Desktop\comparing_file\a.txt';
my $outfile = 'C:\Documents and Settings\dinesh.lohan\Desktop\comparing_file\1.txt';
my %results = (); 
open FILE1, "$f1" or die "Could not open file: $! \n";
while(my $line = <FILE1>){   $results{$line}=1;
}
close(FILE1); 
open FILE2, "$f2" or die "Could not open file: $! \n";
while(my $line =<FILE2>) {  
 $results{$line}++;
}
close(FILE2);  
open (OUTFILE, ">$outfile") or die "Cannot open $outfile for writing \n";
foreach my $line (keys %results) { print OUTFILE $line if $results{$line} == 1;
}
close OUTFILE;