I'd like to be able to do this as well, in my case, I just tweaked it with a tiny wrapper script:
#!/usr/bin/perl
my $tf = "/tmp/tmp-dot-$$-" . time;
open(my $out, ">$tf");
while ( defined(my $line = <STDIN>) )
{
print $out $line;
if ( $line =~ /^digraph/ )
{
print $out "nodesep=0.25;";
print $out "ranksep=1;";
print $out "rankdir=LR;";
}
}
open(STDIN, "<$tf");
unlink($tf);
system("/usr/bin/dot", @ARGV);
I agree I have a project that consists of 22 build jobs that consist of a level hiearchy. I copy/pasted the code and added rankdir=LR and the graph is much more readable so I'd love to see this improvement implemented!