sudo mkdir -p /etc/nginx/cache
sudo chown -R www-data:www-data /etc/nginx/cache

sudo mkdir -p /var/run/cache/nginx
sudo chown -R www-data:www-data /var/run/cache/nginx

http {
    ...
    fastcgi_cache_path /etc/nginx/cache levels=1:2 keys_zone=WORDPRESS_CACHE:100m inactive=60m max_size=256m;
    fastcgi_cache_key "$scheme$request_method$host$request_uri";
    fastcgi_cache_use_stale error timeout invalid_header http_500;
    fastcgi_ignore_headers Cache-Control Expires Set-Cookie;
    ...
}

server {
    ...
    set $skip_cache 0;

	# POST 請求不用快取
	if ($request_method = POST) {
    	set $skip_cache 1;
  	}

  	# 若有 query 參數的網址不用快取
  	if ($query_string != "") {
      	set $skip_cache 1;
  	}

  	# 特殊的網址不用快取
  	if ($request_uri ~* "(/wp-admin/|/xmlrpc.php|/wp-(app|cron|login|register|mail).php|wp-.*.php|/feed/|index.php|wp-comments-popup.php|wp-links-opml.php|wp-locations.php|sitemap(_index)?.xml|[a-z0-9_-]+-sitemap([0-9]+)?.xml)") {
      	set $skip_cache 1;
  	}

  	# 已登入使用者、留言者不用快取
  	if ($http_cookie ~* "comment_author|wordpress_[a-f0-9]+|wp-postpass|wordpress_no_cache|wordpress_logged_in") {
      	set $skip_cache 1;
  	}
    
    #正在維護模式中也略過
	if (-f "$document_root/.maintenance") {
    	set $skip_cache 1;
	}

  	# 加入快取資訊表頭（除錯用）
  	add_header X-Cache $upstream_cache_status;

    location ~ \.php$ {
        include fastcgi_params;
        fastcgi_pass unix:/var/run/php/php8.2-fpm.sock;
        fastcgi_index index.php;
    	include fastcgi.conf;
        
        # FastCGI 快取設定
        fastcgi_cache WORDPRESS_CACHE;
        fastcgi_cache_valid 200 301 302 1d;
        fastcgi_cache_bypass $skip_cache;
    	fastcgi_no_cache $skip_cache;
        
        # 可以加入除錯用的標頭
        add_header X-Cache "$upstream_cache_status From $host";
    	add_header Cache-Control  max-age=0;
    	add_header Nginx-Cache "$upstream_cache_status";
    	add_header Last-Modified $date_gmt;
    }
    ...
}

fastcgi_cache_bypass $cookie_user_logged_in;
fastcgi_no_cache $cookie_user_logged_in;

rm -rf /path/to/your/nginx/cache/*

location /purge_cache/ {
    allow 127.0.0.1; # 允許本地
    allow '多個主機ip';
    deny all; # 拒绝其他所有请求
    fastcgi_cache_purge WORDPRESS_CACHE $scheme$request_method$host$request_uri;
}

curl -X GET http://your-domain.com/purge_cache/the_uri_to_purge

map $http_user_agent $is_desktop {
    default 0;
    ~*linux.*android|windows\s+(?:ce|phone) 0; # exceptions to the rule
    ~*spider|crawl|slurp|bot 1; # bots
    ~*windows|linux|os\s+x\s*[\d\._]+|solaris|bsd 1; # OSes
}

## Revert the logic.
map $is_desktop $is_mobile {
    1 0;
    0 1;
}
add_header x-ua-device $is_mobile;

# cache key 要加入 is_moubile
fastcgi_cache_key "$scheme$request_method$host$request_uri$is_mobile";

nano start-fastcgi.sh
chmod +x start-fastcgi.sh

mkdir -p /var/run/cache/nginx
chown -R www-data:www-data /var/run/cache/nginx
systemctl restart nginx

sudo nano /etc/rc.local

#!/bin/bash
bash /home/yourname/start-fastcgi.sh

exit 0

sudo nano /etc/systemd/system/rc-local.service

[Unit]
Description=/etc/rc.local Compatibility
ConditionPathExists=/etc/rc.local

[Service]
Type=forking
ExecStart=/etc/rc.local start
TimeoutSec=0
StandardOutput=tty
RemainAfterExit=yes
SysVStartPriority=99

[Install]
WantedBy=multi-user.target

sudo chmod +x /etc/rc.local
sudo systemctl enable rc-local.service
sudo systemctl start rc-local.service