use warnings;
use strict;

while(<DATA>)
{
   #some conversions here
   if($_ =~ /<EMP>/g)
   {
      print;
   }
}

__DATA__
PT    23    0.05
PK    27    0.21
<EMP>P7    22    0.12
PP    21    0.22
P3    21    0.20
P1    21    0.92
<EMP>P1    23    0.82
P2    22    0.12
[download]

Prints:

<EMP>P7    22    0.12
<EMP>P1    23    0.82
[download]

as expected. What's the problem?

Added:

Oh, and the /g (global) switch is not required - the first match in the line should be sufficient.