How to use ps command to debug a Node program when it stops working

In recent years, Node.js has become the top tool in the field of front-end development. Its efficiency, reliability and ease of use are loved by users. However, Node.js also has its fragile side, such as problems such as the program suddenly stopping working. Next, we’ll cover how to use the PS (Process Status) command to debug a Node.js program when it stops working.

1. Understand the PS command

The PS command is a commonly used process status query tool in Linux systems. Its function can query the processes running in the system. Can be used to check system stability and perform other tasks. In this example, we will use the PS command to check the status of the Node.js process.

2. Use the PS command in Node.js

1. Use the PS command to view the process status

Enter the PS command in the terminal:

ps aux | grep node

Among them, "ps" represents the process status, "aux" represents the processes of all users, and "grep node" is the search keyword. The above command will query the system for any process starting with "node" and return relevant information.

2. Kill the Node.js process

If the Node.js process unfortunately stops working, you may need to kill the process. To do this, you need to first find the process ID (PID) and kill it using the kill command.

After using PS to search for the Node.js process, the PID value will be returned. For example:

user    12345   0.0  2.3  23454  4567 /usr/bin/nodejs /path/to/your/app.js

where "12345" is the PID value of the Node.js process. Use the following command to kill the process:

kill -9 12345

3. End the Node.js process

In Node.js, we can use the process.exit() method to end it process. This method directly ends the process, so it needs to be used with caution. Add the following code to the program code to end the Node.js process. For example:

if (error) {
   console.log('出现错误，结束进程！');
   process.exit();
}

4. Use Nodemon to monitor processes

Nodemon is a tool for monitoring Node.js applications and can automatically restart the application. Started the application using Nodemon monitoring process. If an application is found to have exited abnormally, Nodemon can automatically restart the application to help the application return to normal. We only need to enter the command "nodemon app.js" on the command line to start using Nodemon to monitor Node.js applications individually.

3. Summary

This article introduces how to use the PS command to track the Node.js process status, kill the Node.js process, end the Node.js process and use Nodemon to monitor the Node.js process. . Therefore, when the Node.js process stops working unexpectedly, in the terminal with Node.js open, you can use these methods to diagnose the cause of the problem and restore the Node.js process. These skills are quite necessary for Node.js developers.

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