Analysis of the reasons why PHP7-FPM cannot be started in Linux system

"Analysis of the reasons why PHP7-FPM cannot be started in Linux systems"

In Linux systems, PHP7-FPM is a common PHP FastCGI Process Manager. Use For managing and processing PHP scripts. However, sometimes you will encounter the problem of being unable to start when configuring PHP7-FPM, which may be due to various reasons. In this article, we'll examine several common causes and provide corresponding code examples to help resolve the issue.

1. Configuration file error

First, make sure that the configuration file of PHP7-FPM (usually /etc/php/7.X/fpm/php-fpm.conf) There are no problems caused by syntax errors or incorrect configuration item settings. You can test the syntax correctness of the configuration file by using the php-fpm -t command. The following is an example of an error in a sample configuration file:

listen = 127.0.0.1:9000
; 错误的listen配置应为：
; listen = 127.0.0.1:9000

2. Necessary extensions not installed

PHP7-FPM may require some PHP extensions at runtime to support its functionality, if necessary is missing extension, PHP7-FPM may not start. You can view related error information by viewing the log file of php7-fpm (usually in /var/log/php7-fpm.log). The following is an example of an error caused by a sample extension not being installed:

[22-Feb-2022 10:00:00] ERROR: Unable to load dynamic library 'mysqli.so' (tried: /usr/lib/php/20170718/mysqli.so (No such file or directory), /usr/lib/php/20170718/mysqli.so.so (No such file or directory))

3. Permission issues

PHP7-FPM may fail at startup due to permission issues that prevent it from accessing necessary files or directories. Make sure that the running user of PHP7-FPM (usually the www-data or nginx user) has sufficient permissions to access relevant files and directories. The following is an example of an error caused by a permission issue:

[22-Feb-2022 10:00:00] ERROR: Unable to open primary script '/var/www/html/index.php' (Permission denied)

4. Port conflict

In the Linux system, if other processes are already using the listening port configured by PHP7-FPM (the default is 9000), PHP7-FPM may not start. You can view the ports used in the system by using the netstat -tuln command. The following is an example of an error caused by a port conflict:

[22-Feb-2022 10:00:00] ERROR: FPM initialization failed: couldn't open control file '/var/run/php-fpm/php-fpm.sock': No such file or directory

Conclusion

In a Linux system, PHP7-FPM cannot be started due to a variety of reasons, including configuration file errors and lack of necessary Extensions, permission issues, port conflicts, etc. By carefully analyzing the error logs and configuration files, combined with the code examples provided above, you can more easily troubleshoot and solve the problem of PHP7-FPM failing to start. Hope this article will be helpful to you.

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