Go by Example: Directories

Go has several useful functions for working with directories in the file system.
	`package main`
	`import ( "fmt" "io/fs" "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")`
Helper function to create a new empty file.	`createEmptyFile := func(name string) { d := []byte("") check(os.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.DirEntry` objects.	`c, err := os.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 = os.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. `WalkDir` accepts a callback function to handle every file or directory visited.	`fmt.Println("Visiting subdir") err = filepath.WalkDir("subdir", visit) }`
`visit` is called for every file or directory found recursively by `filepath.WalkDir`.	`func visit(path string, d fs.DirEntry, err error) error { if err != nil { return err } fmt.Println(" ", path, d.IsDir()) return nil }`

$ go run directories.go
Listing subdir/parent
  child true
  file2 false
  file3 false
Listing subdir/parent/child
  file4 false
Visiting subdir
  subdir true
  subdir/file1 false
  subdir/parent true
  subdir/parent/child true
  subdir/parent/child/file4 false
  subdir/parent/file2 false
  subdir/parent/file3 false

Next example: Temporary Files and Directories.