Nginx 入门（一）Nginx 配置Web服务器
引言
Nginx作为高性能的web和反向代理服务器，在互联网公司应用广泛。作为一名刚入职的小白，9月底的时候经历了公司站点的HTTPS改造，虽然没有亲手配置nginx, 而且一开始看到Nginx配置还是很懵逼的 （为什么本科学校不专门学一下啊？%>_<% 还是怪自己不够主动去学），本文写给从没接触过Nginx的同学，也算是入门，不会太深入，有兴趣的同学可以买
《深入理解Nginx》, （真的要有兴趣啊，很厚的一本书），个人觉得作为开发人员知道一些基本配置就行了，没必要特别深入。
Nginx的安装
首先介绍一下Nginx的在不同系统下的安装
<span class="token preprocessor property"># CentOS</span>
yum install nginx<span class="token punctuation">;</span>
<span class="token preprocessor property"># Ubuntu</span>
sudo apt<span class="token operator">-</span><span class="token keyword">get</span> install nginx<span class="token punctuation">;</span>
<span class="token preprocessor property"># Mac</span>
brew install nginx<span class="token punctuation">;</span>
本文主要以Mac下的安装为例。
通过homebrew，nginx默认被安装在
/usr/local/Cellar/nginx/目录下。conf安装目录在
/usr/local/etc/nginx/nginx.conf
启动、热重启、关闭以及测试配置的命令如下：
# 启动
nginx -s start;
# 重新启动，热启动，修改配置重启不影响线上
nginx -s reload;
# 关闭
nginx -s stop;
# 修改配置后，可以通过下面的命令测试是否有语法错误
nginx -t;
在浏览器中键入
http://localhost:8080,即可访问到nginx的欢迎界面。那么，为什么会访问到nginx的欢迎界面的呢？
不妨打开nginx.conf，一起来分析一下这个文件。在nginx的配置中用
#表示注释
<span class="token preprocessor property">#user nobody;</span>
<span class="token preprocessor property">##定义拥有和运行Nginx服务的Linux系统用户</span>
worker_processes <span class="token number">1</span><span class="token punctuation">;</span>
<span class="token preprocessor property">##定义单进程。通常将其设成CPU的个数或者内核数</span>
<span class="token preprocessor property">#error_log logs/error.log;</span>
<span class="token preprocessor property">#error_log logs/error.log notice;</span>
<span class="token preprocessor property">#error_log logs/error.log info;</span>
<span class="token preprocessor property">##定义Nginx在哪里打日志</span>
<span class="token preprocessor property">#pid logs/nginx.pid;</span>
<span class="token preprocessor property">##Nginx写入主进程ID（PID）</span>
events <span class="token punctuation">{</span>
worker_connections <span class="token number">1024</span><span class="token punctuation">;</span>
<span class="token preprocessor property">##通过worker_connections和worker_processes计算maxclients。</span>
<span class="token preprocessor property">##max_clients = worker_processes * worker_connections</span>
<span class="token punctuation">}</span>
http <span class="token punctuation">{</span>
include mime<span class="token punctuation">.</span>types<span class="token punctuation">;</span>
<span class="token preprocessor property">##在/opt/nginx/conf/mime.types写的配置将在http模块中解析</span>
default_type application<span class="token operator">/</span>octet<span class="token operator">-</span>stream<span class="token punctuation">;</span>
<span class="token preprocessor property">#log_format main </span><span class="token string">'$remote_addr - $remote_user [$time_local] "$request" '</span>
<span class="token preprocessor property"># </span><span class="token string">'$status $body_bytes_sent "$http_referer" '</span>
<span class="token preprocessor property"># </span><span class="token string">'"$http_user_agent" "$http_x_forwarded_for"'</span><span class="token punctuation">;</span>
<span class="token preprocessor property">#access_log logs/access.log main;</span>
sendfile on<span class="token punctuation">;</span>
<span class="token preprocessor property">##如果是为了获取本地存储的静态化文件，sendfile可以加速服务端，但是如果是反向代理，那么该功能就失效了。</span>
<span class="token preprocessor property">#tcp_nopush on;</span>
<span class="token preprocessor property">##在 nginx 中，tcp_nopush 配置和 tcp_nodelay </span><span class="token string">"互斥"</span>。它可以配置一次发送数据的包大小。也就是说，它不是按时间累计 <span class="token number">0.2</span> 秒后发送包，而是当包累计到一定大小后就发送。在 nginx 中，tcp_nopush 必须和sendfile 搭配使用。
<span class="token preprocessor property">#keepalive_timeout 0;</span>
keepalive_timeout <span class="token number">65</span><span class="token punctuation">;</span>
<span class="token preprocessor property">##设置保持客户端连接时间</span>
<span class="token preprocessor property">#gzip on;</span>
<span class="token preprocessor property">##告诉服务端用gzip压缩</span>
server <span class="token punctuation">{</span>
<span class="token preprocessor property">##如果你想对虚拟主机进行配置，可以在单独的文件中配置server模块，然后include进来</span>
listen <span class="token number">8080</span><span class="token punctuation">;</span>
<span class="token preprocessor property">##告诉Nginx TCP端口，监听HTTP连接。listen 80; 和 listen *:80;是一样的</span>
server_name localhost<span class="token punctuation">;</span>
<span class="token preprocessor property">##定义虚拟主机的名字</span>
<span class="token preprocessor property">#charset koi8-r;</span>
<span class="token preprocessor property">#access_log logs/host.access.log main;</span>
location <span class="token operator">/</span> <span class="token punctuation">{</span>
<span class="token preprocessor property">##location模块可以配置nginx如何反应资源请求</span>
root html<span class="token punctuation">;</span>
index index<span class="token punctuation">.</span>html index<span class="token punctuation">.</span>htm<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token preprocessor property">#error_page 404 /404.html;</span>
<span class="token preprocessor property"># redirect server error pages to the static page /50x.html</span>
<span class="token preprocessor property">#</span>
error_page <span class="token number">500</span> <span class="token number">502</span> <span class="token number">503</span> <span class="token number">504</span> <span class="token operator">/</span><span class="token number">50</span>x<span class="token punctuation">.</span>html<span class="token punctuation">;</span>
location <span class="token operator">=</span> <span class="token operator">/</span><span class="token number">50</span>x<span class="token punctuation">.</span>html <span class="token punctuation">{</span>
root html<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token preprocessor property"># proxy the PHP scripts to Apache listening on 127.0.0.1:80</span>
<span class="token preprocessor property">#</span>
<span class="token preprocessor property">#location ~ \.php$ {</span>
<span class="token preprocessor property"># proxy_pass http://127.0.0.1;</span>
<span class="token preprocessor property">#}</span>
<span class="token preprocessor property"># pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000</span>
<span class="token preprocessor property">#</span>
<span class="token preprocessor property">#location ~ \.php$ {</span>
<span class="token preprocessor property"># root html;</span>
<span class="token preprocessor property"># fastcgi_pass 127.0.0.1:9000;</span>
<span class="token preprocessor property"># fastcgi_index index.php;</span>
<span class="token preprocessor property"># fastcgi_param SCRIPT_FILENAME /scripts$fastcgi_script_name;</span>
<span class="token preprocessor property"># include fastcgi_params;</span>
<span class="token preprocessor property">#}</span>
<span class="token preprocessor property"># deny access to .htaccess files, if Apache's document root</span>
<span class="token preprocessor property"># concurs with nginx's one</span>
<span class="token preprocessor property">#</span>
<span class="token preprocessor property">#location ~ /\.ht {</span>
<span class="token preprocessor property"># deny all;</span>
<span class="token preprocessor property">#}</span>
<span class="token punctuation">}</span>
<span class="token preprocessor property"># another virtual host using mix of IP-, name-, and port-based configuration</span>
<span class="token preprocessor property">#</span>
<span class="token preprocessor property">#server {</span>
<span class="token preprocessor property"># listen 8000;</span>
<span class="token preprocessor property"># listen somename:8080;</span>
<span class="token preprocessor property"># server_name somename alias another.alias;</span>
<span class="token preprocessor property"># location / {</span>
<span class="token preprocessor property"># root html;</span>
<span class="token preprocessor property"># index index.html index.htm;</span>
<span class="token preprocessor property"># }</span>
<span class="token preprocessor property">#}</span>
<span class="token preprocessor property"># HTTPS server</span>
<span class="token preprocessor property">#</span>
<span class="token preprocessor property">#server {</span>
<span class="token preprocessor property"># listen 443 ssl;</span>
<span class="token preprocessor property"># server_name localhost;</span>
<span class="token preprocessor property"># ssl_certificate cert.pem;</span>
<span class="token preprocessor property"># ssl_certificate_key cert.key;</span>
<span class="token preprocessor property"># ssl_session_cache shared:SSL:1m;</span>
<span class="token preprocessor property"># ssl_session_timeout 5m;</span>
<span class="token preprocessor property"># ssl_ciphers HIGH:!aNULL:!MD5;</span>
<span class="token preprocessor property"># ssl_prefer_server_ciphers on;</span>
<span class="token preprocessor property"># location / {</span>
<span class="token preprocessor property"># root html;</span>
<span class="token preprocessor property"># index index.html index.htm;</span>
<span class="token preprocessor property"># }</span>
<span class="token preprocessor property">#}</span>
include servers<span class="token comment">/*;
}
</span>
虽然上面的默认配置很多，但是可以总体归纳为三个模块：
#全局模块
events {
#events模块
}
http
{
#http全局模块
server
{
#server全局模块
location [PATTERN]{
#location模块
}
}
}
1、全局块：配置影响nginx全局的指令。一般有运行nginx服务器的用户组，nginx进程pid存放路径，日志存放路径，配置文件引入，允许生成worker process数等。
2、events块：配置影响nginx服务器或与用户的网络连接。有每个进程的最大连接数，选取哪种事件驱动模型处理连接请求，是否允许同时接受多个网路连接，开启多个网络连接序列化等。
3、http块：可以嵌套多个server，配置代理，缓存，日志定义等绝大多数功能和第三方模块的配置。如文件引入，mime-type定义，日志自定义，是否使用sendfile传输文件，连接超时时间，单连接请求数等。
4、server块：配置虚拟主机的相关参数，一个http中可以有多个server。
5、location块：配置请求的路由，以及各种页面的处理情况。
Nginx配置Web服务器
先介绍对一个web服务进行简单配置，然后对各个重要点简单说明。这个案例中关于反向代理的要点将在下一篇中介绍。
案列
<span class="token preprocessor property">########### 每个指令必须有分号结束。#################</span>
<span class="token preprocessor property">#user administrator administrators; #配置用户或者组，默认为nobody nobody。</span>
<span class="token preprocessor property">#worker_processes 2; #允许生成的进程数，默认为1</span>
<span class="token preprocessor property">#pid /nginx/pid/nginx.pid; #指定nginx进程运行文件存放地址</span>
error_log log<span class="token operator">/</span>error<span class="token punctuation">.</span>log debug<span class="token punctuation">;</span> #制定日志路径，级别。这个设置可以放入全局块，http块，server块，级别以此为：debug<span class="token operator">|</span>info<span class="token operator">|</span>notice<span class="token operator">|</span>warn<span class="token operator">|</span>error<span class="token operator">|</span>crit<span class="token operator">|</span>alert<span class="token operator">|</span>emerg
events <span class="token punctuation">{</span>
accept_mutex on<span class="token punctuation">;</span> #设置网路连接序列化，防止惊群现象发生，默认为on
multi_accept on<span class="token punctuation">;</span> #设置一个进程是否同时接受多个网络连接，默认为off
<span class="token preprocessor property">#use epoll; #事件驱动模型，select|poll|kqueue|epoll|resig|/dev/poll|eventport</span>
worker_connections <span class="token number">1024</span><span class="token punctuation">;</span> #最大连接数，默认为<span class="token number">512</span>
<span class="token punctuation">}</span>
http <span class="token punctuation">{</span>
include mime<span class="token punctuation">.</span>types<span class="token punctuation">;</span> #文件扩展名与文件类型映射表
default_type application<span class="token operator">/</span>octet<span class="token operator">-</span>stream<span class="token punctuation">;</span> #默认文件类型，默认为text<span class="token operator">/</span>plain
<span class="token preprocessor property">#access_log off; #取消服务日志 </span>
log_format myFormat <span class="token string">'$remote_addr–$remote_user [$time_local] $request $status $body_bytes_sent $http_referer $http_user_agent $http_x_forwarded_for'</span><span class="token punctuation">;</span> #自定义格式
access_log log<span class="token operator">/</span>access<span class="token punctuation">.</span>log myFormat<span class="token punctuation">;</span> #combined为日志格式的默认值
sendfile on<span class="token punctuation">;</span> #允许sendfile方式传输文件，默认为off，可以在http块，server块，location块。
sendfile_max_chunk <span class="token number">100</span>k<span class="token punctuation">;</span> #每个进程每次调用传输数量不能大于设定的值，默认为<span class="token number">0</span>，即不设上限。
keepalive_timeout <span class="token number">65</span><span class="token punctuation">;</span> #连接超时时间，默认为<span class="token number">75</span>s，可以在http，server，location块。
upstream mysvr <span class="token punctuation">{</span>
server <span class="token number">127.0</span><span class="token number">.0</span><span class="token number">.1</span><span class="token punctuation">:</span><span class="token number">7878</span><span class="token punctuation">;</span>
server <span class="token number">192.168</span><span class="token number">.10</span><span class="token number">.121</span><span class="token punctuation">:</span><span class="token number">3333</span> backup<span class="token punctuation">;</span> #热备
<span class="token punctuation">}</span>
error_page <span class="token number">404</span> https<span class="token punctuation">:</span><span class="token operator">/</span><span class="token operator">/</span>www<span class="token punctuation">.</span>baidu<span class="token punctuation">.</span>com<span class="token punctuation">;</span> #错误页
server <span class="token punctuation">{</span>
keepalive_requests <span class="token number">120</span><span class="token punctuation">;</span> #单连接请求上限次数。
listen <span class="token number">4545</span><span class="token punctuation">;</span> #监听端口
server_name <span class="token number">127.0</span><span class="token number">.0</span><span class="token number">.1</span><span class="token punctuation">;</span> #监听地址
location <span class="token operator">~</span><span class="token operator">*</span><span class="token operator">^</span><span class="token punctuation">.</span><span class="token operator">+</span>$ <span class="token punctuation">{</span> #请求的url过滤，正则匹配，<span class="token operator">~</span>为区分大小写，<span class="token operator">~</span><span class="token operator">*</span>为不区分大小写。
<span class="token preprocessor property">#root path; #根目录</span>
<span class="token preprocessor property">#index vv.txt; #设置默认页</span>
proxy_pass http<span class="token punctuation">:</span><span class="token operator">/</span><span class="token operator">/</span>mysvr<span class="token punctuation">;</span> #请求转向mysvr 定义的服务器列表
deny <span class="token number">127.0</span><span class="token number">.0</span><span class="token number">.1</span><span class="token punctuation">;</span> #拒绝的ip
allow <span class="token number">172.18</span><span class="token number">.5</span><span class="token number">.54</span><span class="token punctuation">;</span> #允许的ip
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
域名与端口配置
上述例子中
listen 4545; #监听端口 表示监听端口是4545。但是对于一个小白来说有时候看到
listen [::]:80;,
listen :80;,
listen *:80; 这三种写法还是会很懵逼的，那么他们之间有什么区别啊？
listen [::]:80;表示Nginx会同时监听IPv4和IPv6的80端口，listen :80;,listen *:80; 这两种写法是一样的，
location中URL匹配
上述例子中，大家发现location 后面跟着的正则匹配，其实在nginx中，location url 匹配是遵循一定优先级的。
location = / {
# 完全匹配 =
# 大小写敏感 ~
# 忽略大小写 ~*
}
location ^~ /images/ {
# 前半部分匹配 ^~
# 匹配任何以 /images/ 开头的地址，匹配符合以后，停止往下搜索正则，采用这一条。
}
location ~* \.(gif|jpg|jpeg)$ {
# ~* 表示执行一个正则匹配，不区分大小写
# ~ 表示执行一个正则匹配，区分大小写
# 匹配所有以 gif,jpg或jpeg 结尾的请求
}
location / {
# 如果以上都未匹配，会进入这里
}
location中的优先级如下
(location =) > (location 完整路径) > (location ^~ 路径) > (location ,* 正则顺序) > (location 部分起始路径) > (/)
location <span class="token operator">=</span> <span class="token operator">/</span> <span class="token punctuation">{</span>
<span class="token preprocessor property">#仅仅匹配请求</span>
<span class="token punctuation">[</span> configuration A <span class="token punctuation">]</span>
<span class="token punctuation">}</span>
location <span class="token operator">/</span> <span class="token punctuation">{</span>
<span class="token preprocessor property">#匹配所有以 / 开头的请求。但是如果有更长的同类型的表达式，则选择更长的表达式。如果有正则表达式可以匹配，则优先匹配正则表达式。</span>
<span class="token punctuation">[</span> configuration B <span class="token punctuation">]</span>
<span class="token punctuation">}</span>
location <span class="token operator">/</span>documents<span class="token operator">/</span> <span class="token punctuation">{</span>
<span class="token preprocessor property"># 匹配所有以 /documents/ 开头的请求。但是如果有更长的同类型的表达式，则选择更长的表达式。</span>
<span class="token preprocessor property">#如果有正则表达式可以匹配，则优先匹配正则表达式。</span>
<span class="token punctuation">[</span> configuration C <span class="token punctuation">]</span>
<span class="token punctuation">}</span>
location <span class="token operator">^</span><span class="token operator">~</span> <span class="token operator">/</span>images<span class="token operator">/</span> <span class="token punctuation">{</span>
<span class="token preprocessor property"># 匹配所有以 /images/ 开头的表达式，如果匹配成功，则停止匹配查找。所以，即便有符合的正则表达式location，也</span>
<span class="token preprocessor property"># 不会被使用</span>
<span class="token punctuation">[</span> configuration D <span class="token punctuation">]</span>
<span class="token punctuation">}</span>
location <span class="token operator">~</span><span class="token operator">*</span> \<span class="token punctuation">.</span><span class="token punctuation">(</span>gif<span class="token operator">|</span>jpg<span class="token operator">|</span>jpeg<span class="token punctuation">)</span>$ <span class="token punctuation">{</span>
<span class="token preprocessor property"># 匹配所有以 gif jpg jpeg结尾的请求。但是 以 /images/开头的请求，将使用 Configuration D</span>
<span class="token punctuation">[</span> configuration E <span class="token punctuation">]</span>
<span class="token punctuation">}</span>
文件路径定义
在location模块中可以定义文件路径
比如
根目录设置：
location / {
root /home/barret/test/;
}
主页设置：
index /html/index.html /php/index.php;
try_files 设置
try_file主要是功能是去检查文件是否存在，使用第一个被找到文件返回。如果没有一个文件找到, 那么重定向到最后一个参数指定的URI。如：
location <span class="token operator">/</span>images<span class="token operator">/</span> <span class="token punctuation">{</span>
try_files $uri <span class="token operator">/</span>images<span class="token operator">/</span><span class="token keyword">default</span><span class="token punctuation">.</span>gif<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
location <span class="token operator">=</span> <span class="token operator">/</span>images<span class="token operator">/</span><span class="token keyword">default</span><span class="token punctuation">.</span>gif <span class="token punctuation">{</span>
expires <span class="token number">30</span>s<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
ps: $uri 是不带请求参数的当前URI，下面的全局变量中会介绍
,最后一个参数也可以是命名的location。如下：
try_files $uri $uri.html $uri/index.html @other;
location @other {
# 尝试寻找匹配 uri 的文件，失败了就会转到上游处理
proxy_pass http://localhost:9000;
}
location / {
# 尝试寻找匹配 uri 的文件，没找到直接返回 502
try_files $uri $uri.html =502;
}
Rewrite 重定向
如果要把一个URL
http://www.jianshu.com/users/10001 重写成
http://www.jianshu.com/show?user=10001，可以使用rewrite 规则，参见下面的代码。我在公司站点的改造过程中，遇到了rewrite，重写URL目的是为了更好的SEO。
location <span class="token operator">/</span>users<span class="token operator">/</span> <span class="token punctuation">{</span>
rewrite <span class="token operator">^</span><span class="token operator">/</span>users<span class="token operator">/</span><span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token operator">*</span><span class="token punctuation">)</span>$ <span class="token operator">/</span>show<span class="token operator">?</span>user<span class="token operator">=</span>$<span class="token number">1</span> <span class="token keyword">break</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
rewrite功能就是，使用nginx提供的全局变量或自己设置的变量，结合正则表达式和标志位实现url重写以及重定向。
rewrite 规则 定向路径 重写类型;
1、规则：可以是字符串或者正则来表示想匹配的目标url
2、定向路径：表示匹配到规则后要定向的路径，如果规则里有正则，则可以使用$index来表示正则里的捕获分组
3、重写类型：
last ：相当于Apache里德(L)标记，表示完成rewrite，浏览器地址栏URL地址不变
break；本条规则匹配完成后，终止匹配，不再匹配后面的规则，浏览器地址栏URL地址不变
redirect：返回302临时重定向，浏览器地址会显示跳转后的URL地址
permanent：返回301永久重定向，浏览器地址栏会显示跳转后的URL地址
break 与 last的区别
- last一般写在server和if中，而break一般使用在location中
- last不终止重写后的url匹配，即新的url会再从server走一遍匹配流程，而break终止重写后的匹配
- break和last都能组织继续执行后面的rewrite指令
在location里一旦返回break则直接生效并停止后续的匹配location
举个例子：
server <span class="token punctuation">{</span>
location <span class="token operator">/</span> <span class="token punctuation">{</span>
rewrite <span class="token operator">/</span>last<span class="token operator">/</span> <span class="token operator">/</span>q<span class="token punctuation">.</span>html last<span class="token punctuation">;</span>
rewrite <span class="token operator">/</span><span class="token keyword">break</span><span class="token operator">/</span> <span class="token operator">/</span>q<span class="token punctuation">.</span>html <span class="token keyword">break</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
location <span class="token operator">=</span> <span class="token operator">/</span>q<span class="token punctuation">.</span><span class="token function">html</span> <span class="token punctuation">{</span>
<span class="token keyword">return</span> <span class="token number">400</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
- 访问/last/时重写到/q.html，然后使用新的uri再匹配，正好匹配到locatoin = /q.html然后返回了400
- 访问/break时重写到/q.html，由于返回了break，则直接停止了
if表达式
上面的简单重写很多时候满足不了需求，比如需要判断当文件不存在时、当路径包含xx时等条件，则需要用到if
if的语法如下：
<span class="token selector">if (表达式)</span> <span class="token punctuation">{</span>
<span class="token punctuation">}</span>
内置的全局变量：
$args ：这个变量等于请求行中的参数，同$query_string
$content_length ： 请求头中的Content-length字段。
$content_type ： 请求头中的Content-Type字段。
$document_root ： 当前请求在root指令中指定的值。
$host ： 请求主机头字段，否则为服务器名称。
$http_user_agent ： 客户端agent信息
$http_cookie ： 客户端cookie信息
$limit_rate ： 这个变量可以限制连接速率。
$request_method ： 客户端请求的动作，通常为GET或POST。
$remote_addr ： 客户端的IP地址。
$remote_port ： 客户端的端口。
$remote_user ： 已经经过Auth Basic Module验证的用户名。
$request_filename ： 当前请求的文件路径，由root或alias指令与URI请求生成。
$scheme ： HTTP方法（如http，https）。
$server_protocol ： 请求使用的协议，通常是HTTP/1.0或HTTP/1.1。
$server_addr ： 服务器地址，在完成一次系统调用后可以确定这个值。
$server_name ： 服务器名称。
$server_port ： 请求到达服务器的端口号。
$request_uri ： 包含请求参数的原始URI，不包含主机名，如：”/foo/bar.php?arg=baz”。
$uri ： 不带请求参数的当前URI，$uri不包含主机名，如”/foo/bar.html”。
$document_uri ： 与$uri相同。
内置的条件判断：
-f和!-f用来判断是否存在文件
-d和!-d用来判断是否存在目录
-e和!-e用来判断是否存在文件或目录
-x和!-x用来判断文件是否可执行
有时候在配置文件中看到
$http_host。他和
$host有什么不同呢？
$http_host和$host都是原始的’HOST’字段
比如请求的时候HOST的值是www.csdn.net 那么反代后还是www.csdn.net如果客户端发过来的请求的header中没有有’HOST’这个字段时，
建议使用$host，这时候的$host就等于server_name。
if 表达式例子：
<span class="token comment"># 如果文件不存在则返回400</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span><span class="token operator">-</span>f <span class="token variable">$request_filename</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">return</span> <span class="token number">400</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token comment"># 如果host不是xuexb.com，则301到xuexb.com中</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span> <span class="token variable">$host</span> <span class="token operator">!=</span> <span class="token string">'xuexb.com'</span> <span class="token punctuation">)</span><span class="token punctuation">{</span>
rewrite <span class="token operator">^</span><span class="token operator">/</span><span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token operator">*</span><span class="token punctuation">)</span>$ https<span class="token punctuation">:</span><span class="token operator">/</span><span class="token operator">/</span>xuexb<span class="token punctuation">.</span>com<span class="token operator">/</span>$<span class="token number">1</span> permanent<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token comment"># 如果请求类型不是POST则返回405</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token variable">$request_method</span> <span class="token operator">=</span> <span class="token constant">POST</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">return</span> <span class="token number">405</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token comment"># 如果参数中有 a=1 则301到指定域名</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token variable">$args</span> <span class="token operator">~</span> a<span class="token operator">=</span><span class="token number">1</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
rewrite <span class="token operator">^</span> http<span class="token punctuation">:</span><span class="token operator">/</span><span class="token operator">/</span>example<span class="token punctuation">.</span>com<span class="token operator">/</span> permanent<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
if 通常与location规则搭配使用，如：
# 访问 /test.html 时
location = /test.html {
# 默认值为xiaowu
set $name xiaowu;
# 如果参数中有 name=xx 则使用该值
if ($args ~* name=(\w+?)(&|$)) {
set $name $1;
}
# 301
rewrite ^ /$name.html permanent;
}
文章评论