浅聊关于 nginx 的 rewrite

Syntax:	rewrite regex replacement [flag];
Context:	server, location, if

- last
stops processing the current set of ngx_http_rewrite_module directives and starts a search for a new location matching the changed URI;
完成该rewrite规则的执行后，停止处理后续rewrite指令集；然后查找匹配改变后URI的新location；
- break
stops processing the current set of ngx_http_rewrite_module directives as with the break directive;
完成该rewrite规则的执行后，停止处理后续rewrite指令集，并不再重新查找；但是当前location内剩余非rewrite语句和location外的的非rewrite语句可以执行；
- redirect
returns a temporary redirect with the 302 code; used if a replacement string does not start with “http://”, “https://”, or “$scheme”;
返回302临时重定向，地址栏会显示跳转后的地址；
- permanent
returns a permanent redirect with the 301 code.
返回301永久重定向，地址栏会显示跳转后的地址；即表示如果客户端不清理浏览器缓存，那么返回的结果将永久保存在客户端浏览器中了。

rewrite '^/([0-9]{4})/\d+/\d+/(.*)$' '/$1/$2' last;