How to perform file system scanning

Solution 1:

EDIT FOR 1.16: Enough people still hit this answer, that I thought I'd update it for Go 1.16.

The function filepath.WalkDir introduced in Go 1.16 has better performance than filepath.Walk mentioned in the previous edit. Here's a working example:

package main

import (
    "flag"
    "fmt"
    "io/fs"
    "path/filepath"
)

func visit(path string, di fs.DirEntry, err error) error {
    fmt.Printf("Visited: %s\n", path)
    return nil
}

func main() {
    flag.Parse()
    root := flag.Arg(0)
    err := filepath.WalkDir(root, visit)
    fmt.Printf("filepath.WalkDir() returned %v\n", err)
}

EDIT: Enough people still hit this answer, that I thought I'd update it for the Go1 API. This is a working example of filepath.Walk(). The original is below.

package main

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

func visit(path string, f os.FileInfo, err error) error {
  fmt.Printf("Visited: %s\n", path)
  return nil
} 


func main() {
  flag.Parse()
  root := flag.Arg(0)
  err := filepath.Walk(root, visit)
  fmt.Printf("filepath.Walk() returned %v\n", err)
}

Please note that filepath.Walk walks the directory tree recursively.

This is an example run:

$ mkdir -p dir1/dir2
$ touch dir1/file1 dir1/dir2/file2
$ go run walk.go dir1
Visited: dir1
Visited: dir1/dir2
Visited: dir1/dir2/file2
Visited: dir1/file1
filepath.Walk() returned <nil>

ORIGINAL ANSWER FOLLOWS: The interface for walking file paths has changed as of weekly.2011-09-16, see http://groups.google.com/group/golang-nuts/msg/e304dd9cf196a218. The code below will not work for release versions of GO in the near future.

There's actually a function in the standard lib just for this: filepath.Walk.

package main

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

type visitor int

// THIS CODE NO LONGER WORKS, PLEASE SEE ABOVE
func (v visitor) VisitDir(path string, f *os.FileInfo) bool {
    println(path)
    return true
} 

func (v visitor) VisitFile(path string, f *os.FileInfo) {
    println(path)
}

func main() {
    root := flag.Arg(0)
    filepath.Walk(root, visitor(0), nil)
}

Solution 2:

Here's a way to obtain file information for the files in a directory.

package main

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

func main() {
    dirname := "." + string(filepath.Separator)
    d, err := os.Open(dirname)
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    defer d.Close()
    fi, err := d.Readdir(-1)
    if err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    for _, fi := range fi {
        if fi.Mode().IsRegular() {
            fmt.Println(fi.Name(), fi.Size(), "bytes")
        }
    }
}

Solution 3:

Here is an example to loop through all files and directories recursively. Note that if you want to know whether the path you're appending is a directory just check "f.IsDir()".

package main

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

func main() {
    searchDir := "c:/path/to/dir"

    fileList := []string{}
    err := filepath.Walk(searchDir, func(path string, f os.FileInfo, err error) error {
        fileList = append(fileList, path)
        return nil
    })

    for _, file := range fileList {
        fmt.Println(file)
    }
}

Solution 4:

Package github.com/kr/fs provides a Walker with a very interesting API.

Solution 5:

Go standard package ioutil has built in function for this case scenario see below example

func searchFiles(dir string) { // dir is the parent directory you what to search
    files, err := ioutil.ReadDir(dir)
    if err != nil {
        log.Fatal(err)
    }

    for _, file := range files {
        fmt.Println(file.Name())
    }
}