exec functionality

gistfile1.rb

    def spawn(command)
      fork do
        File.umask self.umask if self.umask
        uid_num = Etc.getpwnam(self.uid).uid if self.uid
        gid_num = Etc.getgrnam(self.gid).gid if self.gid

        ::Dir.chroot(self.chroot) if self.chroot
        ::Process.setsid
        ::Process.groups = [gid_num] if self.gid
        ::Process::Sys.setgid(gid_num) if self.gid
        ::Process::Sys.setuid(uid_num) if self.uid
        self.dir ||= '/'
        Dir.chdir self.dir
        $0 = command
        STDIN.reopen "/dev/null"
        if self.log_cmd
          STDOUT.reopen IO.popen(self.log_cmd, "a")
        else
          STDOUT.reopen file_in_chroot(self.log), "a"
        end
        if err_log_cmd
          STDERR.reopen IO.popen(err_log_cmd, "a")
        elsif err_log && (log_cmd || err_log != log)
          STDERR.reopen file_in_chroot(err_log), "a"
        else
          STDERR.reopen STDOUT
        end
        
        # close any other file descriptors
        3.upto(256){|fd| IO::new(fd).close rescue nil}

        if self.env && self.env.is_a?(Hash)
          self.env.each do |(key, value)|
            ENV[key] = value
          end
        end

        exec command unless command.empty?
      end
    end