Explain the differences between spawn and fork system calls in the context of processes.

In the context of Node.js, system calls fork and spawn are used to create new processes but have different characteristics:

• fork — a specialized method for creating a child process that runs a new instance of Node.js. It creates a process with an IPC channel between parent and child, which is convenient for message exchange. It is commonly used to create workers in Node.js.

• spawn — a more general method for launching any external process (not necessarily Node.js). It starts a new process with the specified command and arguments, without creating an IPC channel by default. It allows more flexible management of the child process's input/output.

Example:

const { fork, spawn } = require('child_process');

// fork launches a new Node.js process
const child1 = fork('script.js');

// spawn launches any external process
const child2 = spawn('ls', ['-lh', '/usr']);

Thus, fork is convenient for creating child Node.js processes with IPC, while spawn is used for running arbitrary commands and programs.