| 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") |
|
| Helper function 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 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()) |
||
} |
||
| `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 |
||
} |