imash 2 varianta:

# 1: one-liner:

>perl -i -pe 's/^\s*$//' some_filename

# 2: programa:
#!/usr/bin/perl

my $file = shift;

-f $file or die "no file given\n";

{
open my $rh, $file or die $!;
open my $wh, "> $file.tmp" or die $!;
while( <$rh> ){
s/^\s*$//;
print $wh $_;
}
close $rh;
close $wh;
rename "$file.tmp", $file;
}

__END__

#~
$_->[/^(?>(.)?(.)+.*)(?!\1)(??{print(($1..$2)[9,0,15,7])})/]
#~