How to recursively list all files in a directory in golang
Jul 09, 2025 am 02:12 AM
The easiest and most reliable way to recursively list all files in Go is to use the filepath.Walk function from the standard library. First, pass the root directory to filepath.Walk and provide a callback function, which will be called on each file and subdirectory; second, only files are processed in the callback function by judging info.IsDir() to be false; finally, filter logic optionally (such as filtering files by extension) and choose to skip or return an error immediately when an error is encountered to ensure program robustness.
In Go, recursively listing all files in a directory is a common task, especially when dealing with file management or data scanning. The easiest and most reliable way to do this is by using the filepath.Walk function from the standard library.
Using filepath.Walk to Traverse Directories
Go's filepath.Walk function lets you walk through a directory tree, calling a function for each file and subdirectory. This is perfect for recursive file listing.
Here's a basic example:
package main
import (
"fmt"
"os"
"path/filepath"
)
func main() {
root := "/your/target/directory"
err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
if err != nil {
return err
}
if !info.IsDir() {
fmt.Println(path)
}
return nil
})
if err != nil {
fmt.Printf("Error: %v\n", err)
}
}- You pass in the root directory.
- The function gets called for every file and folder.
- We check
!info.IsDir()to only print files, not directories.
This approach handles nested folders automatically and avoids writing loops manually.
Filtering Files (Optional but Useful)
Sometimes you don't want all files — maybe just .txt or .log files. You can easily add filtering inside the walk function.
For example, to list only .txt files:
if !info.IsDir() && strings.HasSuffix(info.Name(), ".txt") {
fmt.Println(path)
}You can also use more complex logic like checking file size, modification time, or even reading parts of the file content if needed.
Some things to note:
- Make sure your filter conditions are efficient.
- Avoid doing heavy processing inside the walk function unless necessary.
- Use helper functions if the logic gets too long.
Handling Errors Gracefully
Directory walking can hit permission issues or broken symlinks. By default, filepath.Walk stops on any error unless you handle it.
Inside your walk function, if you return an error, the walk will stop. If you want to skip problematic paths and keep going, just log them and return nil .
Example:
if err != nil {
fmt.Fprintf(os.Stderr, "can't access %q: %v\n", path, err)
return nil // skip and continue
}Alternatively, if you want to stop immediately on first error, return that error.
This kind of control helps avoid crashes during large directory scans.
Alternative: Using ioutil.ReadDir with Recursion (Manual Way)
If you're curious how it works under the hood, you can manually implement recursion using os.ReadDir (or ioutil.ReadDir in older versions). But this requires writing more code and handling edge cases yourself.
Here's a simplified version:
func listFiles(dir string) error {
entries, err := os.ReadDir(dir)
if err != nil {
return err
}
for _, entry := range entries {
path := filepath.Join(dir, entry.Name())
if entry.IsDir() {
listFiles(path) // recursive call
} else {
fmt.Println(path)
}
}
return nil
} While this gives you more control, it lacks some built-in features of filepath.Walk , like better error handling and order guarantees.
So for most use cases, stick with filepath.Walk . It's simple, safe, and does exactly what you need without reinventing the wheel.
Basically that's it.
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