files

files

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.