1st line
2nd line, next line is just a newline

4th line, next line spaces and newline
   
6th and last line

##</code><code>##

use strict;
use warnings;

my $inFile = q{spw592594.dat};
open my $inFH, q{<}, $inFile
   or die qq{open: $inFile: $!\n};

while (<$inFH>)
{
    chomp;
    next unless $_;
    print qq{-->$_<--\n};
}

close $inFH
   or die qq{close: $inFile: $!\n};

##</code><code>##

-->1st line<--
-->2nd line, next line is just a newline<--
-->4th line, next line spaces and newline<--
-->   <--
-->6th and last line<--

##</code><code>##

...
while (<$inFH>)
{
    chomp;
    # reject if 0 or more spaces anchored to start and end
    next if m{^\s*$};
    print qq{-->$_<--\n};
}
...

##</code><code>##

-->1st line<--
-->2nd line, next line is just a newline<--
-->4th line, next line spaces and newline<--
-->6th and last line<--