Editing Web application troubleshooting

網站應用程式技術問題排除

== Web script level ==

* Understanding the meaning of critical HTTP status codes 4xx, 5xx [[Troubleshooting of HTTP errors]]
* Javascript
* Backend script

== Database level ==

* 確認資料庫連線有建立？
* 確認資料庫 SQL 查詢語法是否正確？或者逾時？ [https://dev.mysql.com/doc/refman/5.7/en/error-log.html MySQL :: MySQL 5.7 Reference Manual :: 5.4.2 The Error Log]

== Web server level ==

* [https://httpd.apache.org/docs/2.4/logs.html Log Files - Apache HTTP Server Version 2.4] on {{Win}} & {{Linux}}
* [https://docs.nginx.com/nginx/admin-guide/monitoring/logging/ Configuring Logging | NGINX Plus] on {{Win}} & {{Linux}}
* [https://docs.microsoft.com/zh-tw/windows/win32/http/iis-logging IIS 記錄 - Win32 apps | Microsoft Docs] on {{Win}}

Example command: This command is used to view the last few lines of the Nginx server's error log file.
<pre>
sudo tail /var/log/nginx/error.log
</pre>

* sudo: Execute with administrator privileges
* tail: Display the end portion of a file
* /var/log/nginx/error.log: Default path for Nginx error log file

You can add -f parameter to monitor the log file in real-time:

== OS level ==

* {{Win}} 系統管理工具 (Administrative Tools) -> 事件檢視器 (Event Viewer)
* {{Linux}} 

{{Template:Troubleshooting}}

[[Category: Programming]]
[[Category: Linux]]