use strict;
use warnings;

my $searchstring = '/pptai/nightly_db/data_loader_logs';

open my $rfh, '<', '2010-06-18_AIX_nightly_data_loader.log' or die "cannot open file:$!\n";

while (defined($_ = <$rfh>)) {
   if (0 <= index $_, $searchstring) {
      # file name is part of the current line
      print ;
      last;
   }
}

close $rfh or die "cannot close:$!\n";