yum install httpd-tools

完成后，就可以直接运行ab

# which ab
/usr/bin/ab

# rpm -qf /usr/bin/ab
httpd-tools-2.2.15-47.el6.centos.1.x86_64

# which htpasswd
/usr/bin/htpasswd

压测方法，一定要指定页面名

/usr/bin/ab  -n 3000 -c 3000 https://www.baidu.com/index.php

压测之前先执行下面命令

ulimit -n 65535​