use strict;
use warnings;
use 5.010;


my $file = "/usr/sap/SID/SYS/profile/DEFAULT.PFL";
my $search = 'dbhost';

open my $fh, '<', $file or die "open($file,ro) failed: $!";

my $seen = ' ';

LINE:
while ( my $line = <$fh> ) {

  # skip lines without search string 
  next LINE   if index( lc($line), lc($search), 0 ) < 0;

  # extract the third field of line
  my $third = ( split( ' ', $line, ) )[2] // '';

  # keep the fields uniq
  say $third  unless $third eq $seen;
  $seen = $third;
}
close $fh;