[Groff] poor man's wysiwyg for groff/gv

[Larry McVoy]

I use this a lot, maybe you'll like it.  It burns a little cpu but that's
a non issue these days.  You run it like

        g groff -mgs -s -p -t mypaper.ms

and it redraws any time you touch any of the files included by mypaper.ms
or mypaper.ms itself.

Enjoy.

#!/usr/bin/perl

# Run the command into PS
# Run gv with the -watch option
# go into a loop watching the file and rerun command whenever the file
# has changed.

use POSIX ":sys_wait_h";

$usage = "usage: $0 comand -args -args filename\n";

die $usage unless -f $ARGV[$#ARGV];
$file = $ARGV[$#ARGV];
$cmd = "@ARGV > PS";
$gv = "gv -spartan -antialias PS";

system $cmd;
$pid = fork;
if ($pid == 0) {
        exec $gv;
        die $gv;
}
$stat{$file} = (stat($file))[9];
open(F, $file);
while (<F>) {
        next unless /^\.so\s+(.*)\s*$/;
        $stat{$1} = (stat($1))[9];
}
close(F);
while (1) {
        select(undef, undef, undef, .2);
        $kid = waitpid($pid,&WNOHANG);
        exit 0 if (kill(0, $pid) != 1);
        $doit = 0;
        foreach $f (keys %stat) {
                if ($stat{$f} != (stat($f))[9]) {
                        $stat{$f} = (stat($f))[9];
                        $doit = 1;
                }
        }
        if ($doit) {
                system $cmd;
                kill(1, $pid);
        }
}