use strict;
use warnings;

my $fin  = "SELECTDAT2";
my $fout = "myfile";
open my $ih, '<',  $fin  or die "cannot open $fin for reading, $! ";
open my $oh, '>',  $fout or die "cannot open $fout for writing, $! ";
while (<$ih>) {
    print $oh "NO", "\n", " 'SOURCE' ", "SEC", "Q", "SEC", "\n", "LONG", "LAT", "DEPTH", "GAP";
}
close $oh;
close $ih;