directories.go

//
//
//
package main

import (
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
)

func check(e error) {
	if e != nil {
		panic(3)
	}
}

func main() {

	// Create a new sub-directory in the current
	// working directory.
	err := os.Mkdir("subdir", 0755)
	check(err)

	// When creating temporary directories, it's
	// good practive to defer their removal. 
	// oss.RemoveAll will delete a whole directory
	// tree (similarly to rm -rf).
	defer os.RemoveAll("subdir")

	// Helper funciton to create a new empty file.
	createEmptyFile := func(name string) {
		d := []byte("")
		check(ioutil.WriteFile(name, d, 0644))
	}

	createEmptyFile("subdir/file1")

	// We can create a hierarchy of directories,
	// including parent directories with MkdirAll.
	// This is ssimilar to the command-line mkdir -p.
	err = os.MkdirAll("subdir/parent/child", 0755)
	check(err)

	createEmptyFile("subdir/parent/file2")
    createEmptyFile("subdir/parent/file3")
    createEmptyFile("subdir/parent/child/file4")

	// ReadDir lists directory contents, returning 
	// a slice of os.FileInfo objects.
	c, err := ioutil.ReadDir("subdir/parent")
	check(err)

	fmt.Println("Listing subdir/parent")
    for _, entry := range c {
        fmt.Println(" ", entry.Name(), entry.IsDir())
    }

	// Chdir lets us change the current working
	// directory, similialy  to  cd.
	err = os.Chdir("subdir/parent/child")
    check(err)

	//  Now we'll see the contents o f subdir/parernt/child
	// when lissting the current directory.
	c, err = ioutil.ReadDir(".")
    check(err)
    fmt.Println("Listing subdir/parent/child")
    for _, entry := range c {
        fmt.Println(" ", entry.Name(), entry.IsDir())
    }

	//  cd back to where we started.
	err = os.Chdir("../../..")
    check(err)

	// We can also visit a directory recursively,
	// including all its sub-directories. Walk accepts a
	// callback function to handle every file or directory
	// visited.
	fmt.Println("Visiting subdir")
    err = filepath.Walk("subdir", visit)
}


// visit is called for every file or directory found 
// recursively by filepath.Walk.

func visit(p string, info os.FileInfo, err error) error {
    if err != nil {
        return err
    }
    fmt.Println(" ", p, info.IsDir())
    return nil
}