用curl模拟http请求大家都会，对于内容也都知道，但是问几个问题
curl http://127.0.0.1/ -H “UA:Curl” -v和curl http://127.0.0.1/ -H “UA:curl” -v一样吗？
curl http://127.0.0.1/ -H “UA:Curl” -v和curl http://127.0.0.1/ -H “Ua:Curl” -v一样吗？
curl http://127.0.0.1/ -X POST -v和curl http://127.0.0.1/ -X post -v 一样吗？

可能就要犹豫了。今天正好翻了rfc，找到了答案。
RFC2616是最早的http1.0的规范，其中规定

• Field names are case-insensitive，

现在rfc2616已经被rfc7230-7237取代，查看了这两个RFC。

rfc7230中3.1.1. Request Line中明确说明：

• The request method is case-sensitive.
• Recipients of an invalid request-line SHOULD respond with either a 400 (Bad Request) error or a 301 (Moved Permanently) redirect with the request-target properly encoded. A recipient SHOULD NOT attempt to autocorrect and then process the request without a redirect, since the invalid request-line might be deliberately crafted to bypass security filters along the request chain.

上面意思是说请求行里的请求方法是大小写敏感的，，收到不认识的请求方法时，应该返回400或者301重定向，而不应该修改请求方法然后继续处理。

rfc7231中4. Request Methods中说明

• By convention, standardized methods are defined in all-uppercase US-ASCII letters.
• All general-purpose servers MUST support the methods GET and HEAD. All other methods are OPTIONAL.

两句意思是方法应该是全大写ASCII字母，所有通用服务器必须支持GET和head.其他方法是可选的。

现在知道开始问题的答案了吧