鱼漂 (一直漂)

location
语法:location [=|~|~*|^~] /uri/ { … }
默认:否

上下文:server

这个指令随URL不同而接受不同的结构。你可以配置使用常规字符串和正则表达式。如果使用正则表达式，你必须使用 ~* 前缀选择不区分大小写的匹配或者 ~ 选择区分大小写的匹配。

确定 哪个location 指令匹配一个特定指令，常规字符串第一个测试。常规字符串匹配请求的开始部分并且区分大小写，最明确的匹配将会被使用（查看下文明白 nginx 怎么确定它）。然后正则表达式按照配置文件里的顺序测试。找到第一个比配的正则表达式将停止搜索。如果没有找到匹配的正则表达式，使用常规字符串的结果。

有两个方法修改这个行为。第一个方法是使用 “=”前缀，将只执行严格匹配。如果这个查询匹配，那么将停止搜索并立即处理这个请求。例子：如果经常发生”/”请求，那么使用 “location = /” 将加速处理这个请求。

第二个是使用 ^~ 前缀。如果把这个前缀用于一个常规字符串那么告诉nginx 如果路径匹配那么不测试正则表达式。

而且它重要在于 NGINX 做比较没有 URL 编码，所以如果你有一个 URL 链接’/images/%20/test’ , 那么使用 “images/ /test” 限定location。

总结，指令按下列顺序被接受:
1. = 前缀的指令严格匹配这个查询。如果找到，停止搜索。
2. 剩下的常规字符串，长的在前。如果这个匹配使用 ^~ 前缀，搜索停止。
3. 正则表达式，按配置文件里的顺序。
4. 如果第三步产生匹配，则使用这个结果。否则使用第二步的匹配结果。

例子：

location = / {
# 只匹配 / 查询。
[ configuration A ]
}

location / {
# 匹配任何查询，因为所有请求都已 / 开头。但是正则表达式规则和长的块规则将被优先和查询匹配。
[ configuration B ]
}

location ^~ /images/ {
# 匹配任何已 /images/ 开头的任何查询并且停止搜索。任何正则表达式将不会被测试。
[ configuration C ]
}

location ~* \.(gif|jpg|jpeg)$ {
# 匹配任何已 gif、jpg 或 jpeg 结尾的请求。然而所有 /images/ 目录的请求将使用 Configuration C。
[ configuration D ]
}

例子请求:

/ -> configuration A

/documents/document.html -> configuration B

/images/1.gif -> configuration C

/documents/1.jpg -> configuration D

注意：按任意顺序定义这4个配置结果将仍然一样。

(location =) > (location 完整路径 ) >(location ^~ 路径) >(location ~*, ~ 正则) >(location 部分起始路径)
正则表达式根据配置文件中的前后顺序影响匹配, 前面的优先匹配. 其它则根据匹配长度来优先匹配.

参考:
http://wiki.nginx.org/NginxHttpCoreModule#location

This directive allows different configurations depending on the URI. It can be configured using both literal strings and regular expressions. To use regular expressions, you must use a prefix:

1. "~" for case sensitive matching
2. "~*" for case insensitive matching

To determine which location directive matches a particular query, the literal strings are checked first. Literal strings match the beginning portion of the query - the most specific match will be used. Afterwards, regular expressions are checked in the order defined in the configuration file. The first regular expression to match the query will stop the search. If no regular expression matches are found, the result from the literal string search is used.

For case insensitive operating systems, like Mac OS X or Windows with Cygwin, literal string matching is done in a case insensitive way (0.7.7). However, comparison is limited to single-byte locale's only.

Regular expression may contain captures (0.7.40), which can then be used in other directives.

It is possible to disable regular expression checks after literal string matching by using "^~" prefix. If the most specific match literal location has this prefix: regular expressions aren't checked.

By using the "=" prefix we define the exact match between request URI and location. When matched search stops immediately. E.g., if the request "/" occurs frequently, using "location = /" will speed up processing of this request a bit as search will stop after first comparison.

On exact match with literal location without "=" or "^~" prefixes search is also immediately terminated.

To summarize, the order in which directives are checked is as follows:

1. Directives with the "=" prefix that match the query exactly. If found, searching stops.
2. All remaining directives with conventional strings. If this match used the "^~" prefix, searching stops.
3. Regular expressions, in the order they are defined in the configuration file.
4. If #3 yielded a match, that result is used. Otherwise, the match from #2 is used.

It is important to know that nginx does the comparison against decoded URIs. For example, if you wish to match "/images/%20/test", then you must use "/images/ /test" to determine the location.