Next Welcome to my ~/bin 90

`printd`

Caution: system programming ahead

        use strict;
        use Sys::Syslog;
        use Fcntl ':flock';
        use lib '/home/mjd/lib';
        use MJD::Print;
        my %CONF = load_conf($CONFIG);
        my $NEXTOP = 0;

        open STDERR, ">>", '/tmp/printd.err' if $CONF{debug_printd};
        print STDERR "printd $$ running\n" if $CONF{debug_printd};
        close STDOUT;
        chdir $CONF{spooldir} 
          or die "Couldn't chdir to spool directory $CONF{spooldir}: $!; aborting";
        open D, "." or die "Couldn't open .: $!; aborting";
        flock D, LOCK_EX | LOCK_NB 
          or exit 0;
        print STDERR "Got lock.\n" if $CONF{debug_printd};
        mainloop();

The only interesting item here is flock

This ensures that only one printd is running at a time

The printd might exit if there is nothing for it to do

When print wants to print, it should also start printd

If printd is already running, that is OK

open D, "." is highly nonportable

open D, "<", $0 would have been a better choice