How to check if a file exists or not in Go/Golang

To check if a file exists or not in Go language, we can make use of os.Stat(filePath) and errors.Is(error, os.ErrNotExist) functions in Go.

Let’s go through an example to understand it further.

Using `os.Stat(filePath)` and `errors.Is(err, os.ErrNotExist)`

I have created a file called file-exists-or-not.txt in the same folder as file-exists.go program.

package main

import (
	"errors"
	"fmt"
	"os"
)

func checkFileExists(filePath string) bool {
	_, error := os.Stat(filePath)
	//return !os.IsNotExist(err)
	return !errors.Is(error, os.ErrNotExist)
}

func main() {

	var filePath string = "file-exists-or-not.txt"

	isFileExist := checkFileExists(filePath)

	if isFileExist {
		fmt.Println("file exist")
	} else {

		fmt.Println("file not exists")
	}

}

I have created a separate utility function checkFileExists() in the above Go program, to check if a file exists or not in the given the file path.

We can combine both os.Stat(filePath) and errors.Is(error, os.ErrNotExist) functions into single statement as shown below.

package main

import (
	"errors"
	"fmt"
	"os"
)

func main() {

	var filePath string = "file-exists-or-not.txt"

	if _, err := os.Stat(filePath); errors.Is(err, os.ErrNotExist) {
		fmt.Println("file not exist")

	} else {
		fmt.Println("file exists")

	}
}

`CreateFile The system cannot find the file specified`

If the file does not exists in the given path, errors.Is() function returns following error message CreateFile The system cannot find the file specified..


var filePath string = "file-not-exists.txt"


if _, err := os.Stat(filePath); errors.Is(err, os.ErrNotExist) {
		fmt.Println(err.Error())
}

Here is the output

>go run check-file-exists-or-not.go
CreateFile file-not-exists.txt: The system cannot find the file specified.

Using `os.Stat(filePath)` and `os.IsNotExist()`

In place of errors.Is(err, os.ErrNotExist) function, we can use os.IsNotExist() function as well.

package main

import (
	"errors"
	"fmt"
	"os"
)

func main() {

    var filePath string = "file-exists-or-not.txt"

  _, error := os.Stat(filePath)
    if error == nil {
        fmt.Println("file %s exists", filePath)
    } else if os.IsNotExist(error) {
        fmt.Println("file %s does not exists", filePath)
    } else {
        fmt.Println("file %s stat error: %v", filePath, error)
    }

}

But according to the Go language documentation we should use errors.Is(err, os.ErrNotExist) instead of os.IsNotExist().

// This function predates errors.Is. It only supports errors returned by
// the os package. New code should use errors.Is(err, fs.ErrNotExist).
func IsNotExist(err error) bool {
	return underlyingErrorIs(err, ErrNotExist)
}

https://github.com/golang/go/blob/master/src/os/error.go#L90-L91

Using `os.Open()`

We can use Go’s os.Open() function to check if a file exist or not.


package main

import (
    "fmt"
    "os"
)

func checkFileExists(filePath string) bool {
    _, error := os.Open(filePath) // For read access.
    return error == nil

}

func main() {

    var filePath string = "file-exists-or-not.txt"

	isFileExist := checkFileExists(filePath)

	if isFileExist {
		fmt.Println("file exist")
	} else {

		fmt.Println("file not exists")
	}

}

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How to check if a file exists or not in Go/Golang

Using os.Stat(filePath) and errors.Is(err, os.ErrNotExist) #

CreateFile The system cannot find the file specified #

Using os.Stat(filePath) and os.IsNotExist() #

Using os.Open() #

Using `os.Stat(filePath)` and `errors.Is(err, os.ErrNotExist)`

`CreateFile The system cannot find the file specified`

Using `os.Stat(filePath)` and `os.IsNotExist()`

Using `os.Open()`