How to get the PID of a post-executed process through the executable file name?

Efficient management of processes: Challenges and strategies for finding process IDs based on executable file names

In software development and system operation and maintenance, it is a common requirement to quickly locate its corresponding process ID (PID) according to the executable file name, especially in scenarios such as hot updates. However, it is not easy to obtain PID directly from the file name, and this article will explore the reasons behind it and the possible solutions.

For example, after executing nginx start or nginx stop command, how to directly find the corresponding nginx process? A seemingly simple requirement is complicated by the lack of direct mapping between the executable and the process. Users expect a convenient mechanism to manage and control processes, but existing methods have limitations.

It is not feasible to obtain PID directly based on the file name. A common method is to traverse the system process list and filter the matching according to the executable file name. In Linux systems, the pgrep command can implement similar functions, but there is still room for improvement in efficiency and accuracy.

However, some services, such as nginx, generate a PID file (such as /run/nginx.pid ) after startup, which records the PID of the process. By reading this file, you can indirectly get the ID of the nginx process. This is a service-specific solution.

In addition, you can also obtain the PID of nginx using systemctl reload nginx and other system management tools. This is because system service managers such as systemd will track and manage the process information of the service.

In summary, although it is impossible to obtain the PID directly through the executable file name, we can implement similar functions through the following strategies:

• Read PID files: Many services will generate PID files, which is an effective way to obtain PIDs.
• Using the system service manager: systemd and other tools, we provide process management functions to obtain the service's PID.
• Process list traversal and matching: This is a common method, but relatively inefficient.

Which method to choose depends on the specific application scenario and service characteristics. For thermal updates that require high efficiency and reliability, it is recommended to combine PID files and system service managers to implement them.

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