open(FH, $filename) or die qq(Could not open file "$filename" for reading.\n);
while(<FH>) {
    # my $line = $_;
    # my @arr = split(\t/, $line);

    # -or-
    my @arr = split(/\t/); # split defaults to $_

    # process @arr values for a single line
    # ...
}
close FH;