Examples of creating, opening, writing, reading, closing, and deleting files.

Node.js

const fs = require("fs");

// create file
fs.closeSync(fs.openSync("test.txt", "w"));

// open file (returns file descriptor)
const fd = fs.openSync("test.txt", "r+");

let wbuf = Buffer.from("hello world.");
let rbuf = Buffer.alloc(12);
let off = 0;
let len = 12;
let pos = 0;

// write file
fs.writeSync(fd, wbuf, pos);

// read file
fs.readSync(fd, rbuf, off, len, pos);

console.log(rbuf.toString());

// close file
fs.closeSync(fd);

// delete file
fs.unlinkSync("test.txt");

Output

hello world.

Go

package main

import (
	"fmt"
	"os"
	"syscall"
)

func main() {
	// create file
	file, err := os.Create("test.txt")
	if err != nil {
		panic(err)
	}

	// close file
	file.Close()

	// open file
	file, err = os.OpenFile("test.txt", os.O_RDWR, 0755)
	if err != nil {
		panic(err)
	}

	// file descriptor
	fd := file.Fd()

	// open file (using file descriptor)
	file = os.NewFile(fd, "test file")

	wbuf := []byte("hello world.")
	rbuf := make([]byte, 12)
	var off int64

	// write file
	if _, err := file.WriteAt(wbuf, off); err != nil {
		panic(err)
	}

	// read file
	if _, err := file.ReadAt(rbuf, off); err != nil {
		panic(err)
	}

	fmt.Println(string(rbuf))

	// close file (using file descriptor)
	if err := syscall.Close(int(fd)); err != nil {
		panic(err)
	}

	// delete file
	if err := os.Remove("test.txt"); err != nil {
		panic(err)
	}
}

Output

hello world.

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