how to use proxy

[jiuli]

set_by_lua $time "local num = tonumber(ngx.var.arg_ts) if num then return (os.time()-num-100) else return 1 end";
if ($time !~ ^-){ #能解析下，这个是怎么匹配的？
more_set_headers 'X-Ts:$time' 'Content-Type:text/plain';
return 403 "token is out of date!";
break;
}

[imlzw]

$time !~ ^- 表示不能为-开头的值，即 $time不是负数值