How to Run Shell Commands with JavaScript

Overview

This guide will demonstrate how to execute shell commands within JavaScript using the child_process module provided by Node's API.

Implementation

To achieve this in JavaScript, you will use the exec function from the child_process module. This function allows you to execute shell commands from within your JavaScript code and access their output.

var exec = require('child_process').exec;

exec('cat *.js bad_file | wc -l',
    function (error, stdout, stderr) {
        console.log('stdout: '   stdout);
        console.log('stderr: '   stderr);
        if (error !== null) {
            console.log('exec error: '   error);
        }
    }
);

In the example above, the exec function is invoked with the shell command cat *.js bad_file | wc -l. This command will execute the cat command to concatenate the contents of all .js files and the non-existent file bad_file. It then pipes the output to the wc -l command, which counts the number of lines in the output.

The exec function takes three additional parameters:

• stdout: Captures the standard output of the command.
• stderr: Captures the standard error output of the command, if any.
• error: Indicates whether an error occurred while executing the command.