files

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

Node.js

  1. const fs = require('fs')
  3. // create file
  4. fs.closeSync(fs.openSync('test.txt', 'w'))
  6. // open file (returns file descriptor)
  7. const fd = fs.openSync('test.txt', 'r+')
  9. let wbuf = Buffer.from('hello world.')
  10. let rbuf = Buffer.alloc(12)
  11. let off = 0
  12. let len = 12
  13. let pos = 0
  15. // write file
  16. fs.writeSync(fd, wbuf, pos)
  18. // read file
  19. fs.readSync(fd, rbuf, off, len, pos)
  21. console.log(rbuf.toString())
  23. // close file
  24. fs.closeSync(fd)
  26. // delete file
  27. fs.unlinkSync('test.txt')

Output

  1. hello world.

Go

  1. package main
  3. import (
  4.     "fmt"
  5.     "os"
  6.     "syscall"
  7. )
  9. func main() {
  10.     // create file
  11.     file, err := os.Create("test.txt")
  12.     if err != nil {
  13.         panic(err)
  14.     }
  16.     // close file
  17.     file.Close()
  19.     // open file
  20.     file, err = os.OpenFile("test.txt", os.O_RDWR, 0755)
  21.     if err != nil {
  22.         panic(err)
  23.     }
  25.     // file descriptor
  26.     fd := file.Fd()
  28.     // open file (using file descriptor)
  29.     file = os.NewFile(fd, "test file")
  31.     wbuf := []byte("hello world.")
  32.     rbuf := make([]byte, 12)
  33.     var off int64
  35.     // write file
  36.     if _, err := file.WriteAt(wbuf, off); err != nil {
  37.         panic(err)
  38.     }
  40.     // read file
  41.     if _, err := file.ReadAt(rbuf, off); err != nil {
  42.         panic(err)
  43.     }
  45.     fmt.Println(string(rbuf))
  47.     // close file (using file descriptor)
  48.     if err := syscall.Close(int(fd)); err != nil {
  49.         panic(err)
  50.     }
  52.     // delete file
  53.     if err := os.Remove("test.txt"); err != nil {
  54.         panic(err)
  55.     }
  56. }

Output

  1. hello world.