runone

#!/usr/bin/perl -w
use strict;

die "usage: $0 lockfile command [arg ...]\n"
  unless @ARGV >= 2;

my $lockfile = shift;

if (-e $lockfile) {
  open FILE, "<$lockfile"
    or die "unable to open file '$lockfile' for reading: $!\n";
  my $pid = <FILE>;
  if (kill 0, $pid) {
    # only warn when the lock is more than an hour old
    print "already running, pid $pid\n"
      if (stat _)[9] < time() - 3600;
    exit(99);
  }
  close FILE;
}

open FILE, ">$lockfile"
  or die "unable to open file '$lockfile' for writing: $!\n";
print FILE $$;
close FILE;

system @ARGV;
my $err = $? >> 8; # perl wtf
unlink $lockfile;

exit($err);