Check if file or directory exists in Golang

check.go

if _, err := os.Stat("/path/to/whatever"); os.IsNotExist(err) {
	// path/to/whatever does not exist
}

if _, err := os.Stat("/path/to/whatever"); !os.IsNotExist(err) {
	// path/to/whatever exists
}

The condition for checking if the folder / file exist is not exactly correct. os.Stat might fail because of permissions, etc, but the file may still exists. So it should be !os.IsNotExist(err). Using err == nil in that case gives wrong result as the file doesn't exist.

fmt.Printf("Error: %s", err)

@yshadow, absolutely right!

Reference: https://stackoverflow.com/a/12518877/4927751

One more thing, os.IsExist() would be blind to EMPTY FILE. Please always consider IsNotExist() instead.

Here is the official implementation of both of the function.

func isExist(err error) bool {
	err = underlyingError(err)
	return err == syscall.EEXIST || err == syscall.ENOTEMPTY || err == ErrExist
}

func isNotExist(err error) bool {
	err = underlyingError(err)
	return err == syscall.ENOENT || err == ErrNotExist
}

Hi all,
very funny behavior of os.stat(). I have written the below code and os.stat() is behaving very wierd.
I am using windows and go lang version : go1.10.1 windows/amd64.
Pls help.

package main

import "os"

func main() {

directoryName := getName()
_, err := os.Stat(directoryName)
if err != nil {
	println("os.Stat(): error for folder name ",directoryName)
	println("and error is : ", err.Error())
	if os.IsNotExist(err ) {
		println("Directory Does not exists.")
	}
} else {
	println("os.Stat(): No Error for folderName : ", directoryName)
}

}
// none of these folder exists on my computer so ideally all the returns statements should give error, but only some are giving.
func getName() string {
//no error if I return the "d:\invalidFolder" value
//return "d:\invalidFolder"
//error if I return the "d:\InvalidFolderName" value
//return "d:\InvalidFolderName"
// error if I return the "d:\xyz\this\folder" value
//return "d:\xyz\this\folder"
// no error if I return the "d:\xyz" value
//return "d:\xyz"
// error, if I return the "d:\doesitgiveError" value
//return "d:\doesitgiveError"
// error if I return "d:\abc" value
return "d:\abc"
}

Backslash \ is escape character, that's why I think you getting this strange behaviour.

Thanks.

like!

Why not use os.IsExist instead of !os.IsNotExist?

Here is an example to explain the difference, why os.IsExist != !os.IsNotExist:

if _, err := os.Stat("/path/to/whatever"); os.IsExist(err) {
	// never triggers, because err is nil if file actually exists
}

if err := os.Mkdir("/path/to/whatever", 0755); os.IsExist(err) {
	// triggers if dir already exists
}

Is this normal? Have anyone here ever typed this long to just test if a file/dir exists in any other modern language?

Thanks for the solution tho.

@digglife Welcome to this duck up Golang world.

👍

what about if need to check for "*.txt" in Linux dir if the file exists or not, I tried *.txt but it's not working at all

if _, err := os.Stat("*.txt"); err == nil {
fmt.Printf("File exists\n");
} else {
fmt.Printf("File does not exist\n");
}

@ravindrabhargava Please have a look at https://golang.org/pkg/path/filepath/#Glob

super!

Great! It was so helpful! 👍

Thanks 👍

Thanks

that helps~

Thanks

I was here.

Thanks

Thanks!

shanks!

haha, although it is trivial still helps a lot ,thanks!

Thanks

thanks 👍

thanks

NB: as the docs say, you should rather now use errors.Is(err, fs.ErrNotExist) instead of os.IsNotExist(err):

This function predates errors.Is. It only supports errors returned by the os package. New code should use errors.Is(err, fs.ErrNotExist).

https://pkg.go.dev/os#IsNotExist