Directories in Go
Go has several useful functions for working with directories in the file system.
package main
import (
"fmt"
"io/ioutil"
"os"
"path/filepath"
)
func check(e error) {
if e != nil {
panic(e)
}
}
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 practice to defer their removal.
// os.RemoveAll will delete a whole directory tree (similarly to rm -rf).
defer os.RemoveAll("subdir")
createEmptyFile := func(name string) {
d := []byte("")
check(ioutil.WriteFile(name, d, 0644))
}
createEmptyFile("subdir/file1")
// We can create a hierarchy of directories, including parents with MkdirAll.
// This is similar 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, similarly to cd.
err = os.Chdir("subdir/parent/child")
check(err)
// Now we’ll see the contents of subdir/parent/child when listing 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())
}
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)
}
func visit(p string, info os.FileInfo, err error) error {
if err != nil {
return err
}
fmt.Println(" ", p, info.IsDir())
return nil
}