How to remove all contents of a directory using Golang?

It might be a stupid answer, but why not simply do?

os.RemoveAll("/tmp/")
os.MkdirAll("/tmp/",FileMode)

Write a simple RemoveContents function. For example,

package main

import (
    "fmt"
    "os"
    "path/filepath"
    "strings"
)

func RemoveContents(dir string) error {
    d, err := os.Open(dir)
    if err != nil {
        return err
    }
    defer d.Close()
    names, err := d.Readdirnames(-1)
    if err != nil {
        return err
    }
    for _, name := range names {
        err = os.RemoveAll(filepath.Join(dir, name))
        if err != nil {
            return err
        }
    }
    return nil
}

func main() {
    dir := strings.TrimSuffix(filepath.Base(os.Args[0]), filepath.Ext(os.Args[0]))
    dir = filepath.Join(os.TempDir(), dir)
    dirs := filepath.Join(dir, `tmpdir`)
    err := os.MkdirAll(dirs, 0777)
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    file := filepath.Join(dir, `tmpfile`)
    f, err := os.Create(file)
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    f.Close()
    file = filepath.Join(dirs, `tmpfile`)
    f, err = os.Create(file)
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    f.Close()

    err = RemoveContents(dir)
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
}

Just use ioutil.ReadDir to get a slice of os.FileInfo types, then iterate through and remove each child item using os.RemoveAll.

package main

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

func main() {
    dir, err := ioutil.ReadDir("/tmp")
    for _, d := range dir {
        os.RemoveAll(path.Join([]string{"tmp", d.Name()}...))
    }
}

That way, you are removing only all the child items and not the parent /tmp folder itself.

I have used this pattern many times before (e.g. test logs, etc.).

func RemoveContents(dir string) error {
    files, err := filepath.Glob(filepath.Join(dir, "*"))
    if err != nil {
        return err
    }
    for _, file := range files {
        err = os.RemoveAll(file)
        if err != nil {
            return err
        }
    }
    return nil
}

You could use filepath.Glob() to get a slice of the contents of the folder, then delete everything it returns. This allows you to use /tmp/* to indicate what you want to delete, and could also be used to delete /tmp/*.go, or /tmp/*/*.go, etc.

package main

import (
    "log"
    "os"
    "path/filepath"
)

func RemoveGlob(path string) (err error) {
    contents, err := filepath.Glob(path)
    if err != nil {
        return
    }
    for _, item := range contents {
        err = os.RemoveAll(item)
        if err != nil {
            return
        }
    }
    return
}    

func main() {
    err := RemoveGlob("/tmp/*")
    if err != nil {
        log.Fatalf("Error removing files: %+v", err)
    }
}