Nginx if location 指令部分应用场景使用说明

location 指令

只有正则匹配（ ~ 和 ~* ）才能使用正则子串

# cat regexp.conf 
server {
    listen 9998;
    server_name _;
    access_log logs/regexp_access.log  main;
    index index.html index.htm;

    location ~ /hello/(.*)/$ {
        set $word $1;
        return 200 '$word\n';
    }

}
# curl 127.0.0.1:9998/hello/nginx/
nginx

前缀匹配（^~ ）不能识别正则表达式，会把正则表达式当成普通字符

# cat regexp.conf 
server {
    listen 9998;
    server_name _;
    access_log logs/regexp_access.log  main;
    index index.html index.htm;

    location ^~ /hello/(.*)/$ {
        set $word $1;
        return 200 'test $word\n';
    }

}
# curl 127.0.0.1:9998/hello/nginx/
<html>
<head><title>404 Not Found</title></head>
<body bgcolor="white">
<center><h1>404 Not Found</h1></center>
<hr><center>openresty</center>
</body>
</html>
# curl 127.0.0.1:9998/hello/(.*)/$
-bash: syntax error near unexpected token `('
# curl 127.0.0.1:9998/hello/\(.*\)/$
test

if 指令

if 的优先级比 location 高，因为 if 指令在 ngx_http_server_rewrite_phase 阶段，location 指令在 ngx_http_find_config_phase 阶段。
if 指令可以使用正则子串

# cat regexp.conf 
server {
    listen 9998;
    server_name _;
    access_log logs/regexp_access.log  main;
    index index.html index.htm;

    location ~ /hello/(.*)/$ {
        set $word $1;
        return 200 '$word\n';
    }

    if ($http_user_agent ~ curl/(.*)) {
        set $curl_version $1;
        return 200 'curl_version: $curl_version\n';
    }

}
# curl 127.0.0.1:9998/hello/nginx/
curl_version: 7.29.0

# cat regexp.conf 
server {
    listen 9998;
    server_name _;
    access_log logs/regexp_access.log  main;
    index index.html index.htm;

    location ~ /hello/(.*)/$ {
        set $word $1;
        return 200 '$word\ncurl_version: $curl_version\n';
    }

    if ($http_user_agent ~ curl/(.*)) {
        set $curl_version $1;
    }

}
# curl 127.0.0.1:9998/hello/nginx/
nginx
curl_version: 7.29.0