"I need to know is there any tool/utlity for Windows XP where in which in can run the perl script line by line debugging mode so, that i can see what's happen to the variables during run time."

Perl has a debugger, learn how to use it here: perldebtut.

I really started counting the lines till 35 before I saw your comment.

something like:

 $line = <FILE>;                 #  <---------- 35
    # this line doesn't work. don't know what's wrong here..
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is easier to find.

anyway, you did it twice:

  @buf = <FILE>;                     # you reading all lines of FILE i
+nto @buf
  foreach $line (@buf) {             # OK! (well, "my $line" would be 
+better)
     $line = <FILE>;                 # but now reading again a single 
+line !?! 
                                     #     which is  undef after EOF
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please less cargo cult programming!

Don't c&p different approaches from other snippets, better try to understand what's happening.

Hi Vijay8l,
Am trying to read directory/subdirectories and for files from a path recursively

Why not use File::Find instead of doing all the jobs yourself.

..reading file content(usually just 1 line in a file) and substituting space with comma from the line.
Are you trying to create a Comma-separated values files? If yes then see Text::CSV.

Just to give a head up, using File::Find and substitution function, I did something very close to what you wanted.

#!/usr/bin/perl
use warnings;
use strict;
use File::Find;

my $base_dir = '...';  # put in your base directory

find( \&wanted, $base_dir );

sub wanted {
    return if $_ eq '.' or $_ eq '..';
    if (-d) {
        print " >>> dive into: $_\n" if -d;
    }
    else {
        readout_file($_);  ## call subroutine readout_file
    }
}

sub readout_file {
    my ($filename) = @_;
    open my $fh, '<', $filename or die "can't open file:$!";
    while (<$fh>) {
        chomp;
        s/ /,/;        ## OR s/ /,/g; if you want 
        print $_, $/;  ## OR any other subroutine you want 
    }
 }

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As mentioned elsewhere you can use find2perl to create a skeleton program for you that does the job very well. But here's a piece of code I have laying around that may or may not work for what you want to do.

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

my $start="/some/path/to/some/where";

crawl($start);

exit(0);

sub crawl {
    my $dir = shift;
    opendir(my $dh,$dir) or die "$dir: $!";
    while (my $entry=readdir($dh)){
        next if ($entry eq '.') || ($entry eq '..');
        printf "%s\n",$entry;
        if ( -d $entry ) {
            crawl($dir . "/" . $entry);
        } 
            
    }
    closedir($dh);
}

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Embelish the output or actions as you need. For instance if I were to use this "real time" I'd add an indentation element or even ASCII art elements to it to make the output more useful.

HTH

Thanks Everyone. @2Teez, what you suggested is what i was looking but now, when put $line conent to some array after doing csv(somma seperated), am not able to get any values to $line or @linecolumns. Can you please suggest help me on how to get the $line value into some array so, that i can pass that array element/value to another sub function.

#!/usr/bin/perl
use warnings;
use strict;
use File::Find;

my $base_dir = 'C:\\TestData';  # put in your base directory 
my ($dirname,$filename,$line);
my (@linecolumns);

find( \&wanted, $base_dir );

sub wanted {
    return if $_ eq '.' or $_ eq '..';
    if (-d) {
        print " >>> dive into: $_\n" if -d;
        $dirname = $_;
    }
    else {
        readout_file($_);  ## call subroutine readout_file
    }
}

sub readout_file {
    my ($filename) = @_;
    open my $fh, '<', $filename or die "can't open file:$!";
    while ($line=<$fh>) {
        chomp;
        $line=~s/ /,/g;        ## OR s/ /,/g; if you want
        print $line, $/;
        push(@linecolumns,$line);
        #print $_, $/;  ## OR any other subroutine you want
        print $linecolumns[0], $/;
        print $filename, $/;
#write_output($dirname,$filename,$linecolumns[0],$linecolumns[3]); ## 
+call subroutine to print std template in output file
    }
 }
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ok, finally i found out that we can use split function to put the comma seperated line into array element.

</codesub readout_file {
    my ($filename) = @_;
    my (@linecolumns);
    open my $fh, '<', $filename or die "can't open file:$!";
    while (<$fh>) {
        chomp;
        ~s/ /,/g;        ## OR s/ /,/g; if you want
        print $_, $/;
        @linecolumns = split(',',$_);
        #print $_, $/;  ## OR any other subroutine you want
        print $linecolumns[0],$/;
        print $filename, $/;
    }
}
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