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NodeJs can automatically restart after modifying the code, saving us the trouble of ctr+c and then using node. But in terms of time, if the project is already online and running normally, and there are not many modifications, then we can do it manually. But if it is in the process of development, every time you finish writing the code, you need to manually stop the service and then restart the service, which is really quite troublesome.

For more information about NodeJs, please refer to our NodeJs tutorial

As a programmer, this kind of repetitiveness can be annoying.

Now here I will introduce several ways to make Nodejs restart automatically, saving you the trouble of manual restart.

Forever implements NodeJs automatic restart

Forever is a client tool that can be used to keep the NodeJs service running in the background. Similarly, it can also detect file changes and automatically restart the NodeJs service.

Forever is installed as follows

$ npm install forever –g

Run the above command, wait for forever to be installed, and then we can use forever.

$ forever start app.js

The above command can start the NodeJs service, and the NodeJs service is already running in the backend. Isn't it very simple? Of course, the above command is the most basic to start the NodeJs service. But we can't view the print information just by running the above command. Therefore, if we need to view the print information, we can output this information to the log file. The command is as follows

$ forever –l /log/forever.log –o /log/out.log –e /log/error.log app.js

In this way, we can view the information printed by using console.log() and other functions in the log file.

The last step is to automatically restart the service after modifying the NodeJs code. To do this, use the -w option.

$ forever –l /log/forever.log –o /log/out.log –e /log/error.log –w app.js

In this way, we can achieve our ultimate goal.

pm2 implements automatic restart of NodeJs

Similarly, like forever , pm2 is also a client tool that can also make the NodeJs service run in the background. It can also detect file changes and automatically restart the NodeJs service.

The pm2 installation method is as follows

$ npm install pm2@latest –g

After running the above command, wait for pm2 installation to complete.

$ pm2 start app.js

Start the NodeJs service.

$ pm2 start –l /log/pm2.log –o /log/out.log –e /log/error.log app.js

Write the NodeJs log, printed information and error information into the log file, and start the NodeJs service.

$ pm2 start –l /log/pm2.log –o /log/out.log –e /log/error.log app.js –watch

The above command can detect file changes and then restart the NodeJs service.

Is it easy to use? Of course, the functions of pm2 are far more than that. For details, please refer to the detailed tutorial of pm2 .

The following is an unconventional method. This method is written by myself according to my own development environment. Please correct me if there are any shortcomings.

Automatic restart of NodeJs through SVN

In actual development, I personally use a Linux server. Every time I finish writing NodeJs code locally, I deploy it to the server through Svn. Of course, this requires the use of the SVN hook post-commit. That is, this file is used to restart NodeJs.

If you have any questions about svn synchronizing code to the server, you can refer to the article "Linux server svn remote code synchronization" .

Now we present the shell code directly

#!/bin/bash
export LANG=zh_CN.UTF-8
 
REPOS="$1"
REV="$2"
SVN=/usr/bin/svn
WEB=/www/nodejs
LOG=/data/home/auto_svn.log
$SVN update $WEB --username uname –password password
 
#To detect whether the node process exists
ps -A | grep node
#
#The $? is 0 if the node process exists,otherwise 1.
#
#If $? is 0,we will kill the node process.
if [ $? -eq 0 ];then
   pid=`ps -A | grep node | awk '{print $1}'`
   kill -9 $pid
fi
#Start the node process
nohup node /www/nodejs/index.js >> /log/nodejs.log 2>&1 &

In this way, we can automatically restart the NodeJs service after modifying the code.

The above are the three methods I want to introduce to you. Of course, it needs to be explained here. There are many ways to make NodeJs restart automatically. It is not immutable. We can choose the corresponding method that suits us according to our own development environment.

Just like the first and second methods, they can be said to be universal methods and can be used in different environments. For the third method, if we use SVN to synchronize the code, then there is no problem. If we do not use SVN to synchronize the code, then it is not applicable. Therefore, which method to use depends on your own development environment.

This article will introduce these methods to you, hoping to be helpful to you.