Here's something that works, but it's pretty ugly with lots of if() statements. If I had more time I would do it differently and make it much more compact.

It assumes quite a bit regarding how your code is lined up. The <%-- and --> MUST be on the same line as the <script> and </script> tags, and said tags must be the only thing on the line (and must be in the file's first column). If this is not how your code is consistently lined up, it will not work, but hopefully it is a decent enough example to get you started:

#!/usr/bin/perl

use warnings;
use strict;

open my $fh, '<', 'file.aspx' or die "Can't open the damn file for rea
+ding!: $!";

my @file_content;

while ( my $line = <$fh> ){
    chomp $line;

    if ( $line =~ /^<script>/ ){
        $line = "<%-- $line";
        push @file_content, "$line\n";
        next;
    }
    elsif ( $line =~ /^<\/script>$/ ){
        $line .= " -->";
        push @file_content, "$line\n";
        next;
   }
    elsif ( $line =~ /^<%--\s+<script>/ ){
        $line =~ s/^<%--\s+//;
        push @file_content, "$line\n";
        next;
    }
    elsif ( $line =~ /^<\/script>\s+-->/ ){
        $line =~ s/\s+-->//;
        push @file_content, "$line\n";
        next;
  }
    push @file_content, "$line\n";
}

close $fh;

open $fh, '>', 'file.aspx' or die "Can't open the damned file for writ
+ing: $!";
print $fh @file_content;
close $fh;
[download]

The file I used had these contents:

<script>
</script>

<%-- <script>
</script> -->
[download]

but if my script structure is like this: <script type="java/js"> </script>,then its not working..any solution

Yes; Follow the advice given to you by RichardK in this post.

Any time you're parsing text, a lot depends on how much the patterns you're trying to match may vary. If your tags may or may not span multiple lines, or may have their attributes in different orders, or other variations, parsing them can be very complicated. (Which is why it's often a good idea to use a module if there is one.) If you know your open and close tags will always be on the same line, and never more than one pair on the same line, it could be pretty simple:

perl -p -i -e 's|(<script.+/script>)|<%-- $1 -->| unless s|<%--(\s*<sc
+ript.+/script>\s*)-->|$1|' *.aspx
[download]

Aaron B.
Available for small or large Perl jobs; see my home node.

You could slurp the file and do a greedy regex substitution over it.

use strict;

my $delim = $/;
$/ = '';
my $file = <DATA>;
$/ = $delim;

$file =~ s/(<%--)?\s*<script(.*)>/($1 ? '' : '<%-- ') . "<script$2>"/i
+ge;
$file =~ s=</script>\s*(-->)?='</script>' . ($1 ? '' : " -->\n")=ige;

print $file;

__DATA__
<script type="java/js">
foobie bletch
</script>
<%-- <script>
zelgo mer
</script> -->
[download]

this code not working temporal..:(..

You might tell us how the code fails for you, and on what input, and what output you get.

You might find it useful to read perlintro for some general pointers.

Please share with us what you have tried.

#!/usr/bin/perl 
my $file_name = "test.txt";
my @aspxfiles=glob('.*aspx');
foreach $file(@aspxfiles)
{

   open(INF,$file) || die "file could not open\n";
my @line;
while(@line = <INF>) {

        if ( $line =~ s/<\/script/<\%\-\-<script/g) {
               open(INF,'>>$file_name') || die "could not open in writ
+e mode";
                
                close(INF);
        } 
        close(INF);
}
}
[download]

this is partial coding which i tried.i'm very weak in scripting language

You are going line-by-line through each file and replacing the string </script with the string <%--<script . I don't know aspx, but I suspect that's not quite what you want. It seems more likely that your opening comment tag would come before your <script> tag, and a closing one after your </script> tag, but you'll have to show us some sample data to know for sure.

If that's successful, you open a file for appending, but you never write anything to it, and you never write your changed $line anywhere. Presumably you want to write it to a file, and perhaps move that file into the place of the original?

ADDED: One more thing: by using single quotes around your output filename, you prevent interpolation, so you will open a file named $file_name, not test.txt.

Aaron B.
Available for small or large Perl jobs; see my home node.