Sigh - use strict; use warnings;, post a complete sample that demonstrates the problem. As usual, here's a starting point:

use strict;
use warnings;

while (my $line = <DATA>) {
...
}

__DATA__
...
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Dodgy stuff in your first post:

$line=; # Just plain wrong!

while ($line=~m/([123]?[.s]*[a-z\=.]+)/oi) # Where does $line get a va
+lue?

$t_book=~s/\l=([a-z]+)\/$1/ig; # The \/ is wrong!

$t_book=~s/<(|/)(B|I|SC|U)>//ig; # The |/ is wrong (and why would you 
+want to capture it?)
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$line=;
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$line=<IN>;
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Furthermore, it might be a good idea to add the /g flag to your regex in the while condition. That way, it won't try to match again and again from the start, but instead it'll continue next time where it left off last time.

while ($line=~m/([123]?[.s]*[a-z\=.]+)/ig)
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jesuashok there are some problems in your code.

You have not assigned any vales to $line

I don't know what are you doing in the below line, which is not necessary. Suppose you need to count the number of occurences, then it might be useful.

Also change the below line

$t_book=~s/<(|/)(B|I|SC|U)>//ig;

into

$t_book=~s/<(\/)?(B|I|SC|U)>//ig; #to delete both opening and closing tags of bold italics etc.

GrandFather has highlighted clearly the other problems. Unless you give exact requirement you cannot get correct solutions. You will get answers only in assumptions.

jesuashok, if your name is Anand Kumar*, it looks like this question was answered for you a few weeks before you asked it here.

Is this you?

* I've later learned that jesuashok signed some of his earlier posts as "Anthony Jesu Ashok", so I'm pretty confident that his name isn't Anand Kumar.

s**lil*;  $*=join'',sort split q**;  s;.*;grr; &&s+(.(.)).+$2$1+; $; =
qq-$_-;s,.*,ahc,;$,.=chop for split q,,,reverse;print for($,,$;,$*,$/)
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