Apache ab测试报 "ab:invalid URL" 错误

Apache ab测试报 “ab:invalid URL” 错误
转载：https://www.ddkiss.com/archives/43.html
今天用apache2自带的ab性能压测工具对自己的网站进行了简单的测试。看了下说明，照着例子试了下，居然不行。
报错如下：

sa@san:~/software/apache2/bin$ ./ab http://www.baidu.com
./ab: invalid URL
Usage: ./ab [options] [http://]hostname[:port]/path
Options are:
    -n requests     Number of requests to perform
    -c concurrency  Number of multiple requests to make
    -t timelimit    Seconds to max. wait for responses
    -b windowsize   Size of TCP send/receive buffer, in bytes
    -p postfile     File containing data to POST. Remember also to set -T
    -u putfile      File containing data to PUT. Remember also to set -T
    -T content-type Content-type header for POSTing, eg.

最后查明原因，很可笑。必须在最后加上一个/，像下面这样

ab http://www.baidu.com/