Check If a File Exists Before Using It

· 184 words · 1 minute read
#file #io #exists #check #os #stat #isnotexists #directory

In this basic example, we check to see if a file exists before interacting with it (otherwise something’s not going to work as expected). We leverage the power of the os standard library and first use the Stat() function, which although it’s usually used to get information about a file, we’re only looking at the errors.

We can’t just check for err == nil because any number of errors could be returned so we pass it to IsNotExists() to confirm that it’s an error because the file does not exist.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

package main

import (
    "fmt"
    "os"
)

func main() {
    if fileExists("example.txt") {
        fmt.Println("Example file exists")
    } else {
        fmt.Println("Example file does not exist (or is a directory)")
    }
}

// fileExists checks if a file exists and is not a directory before we
// try using it to prevent further errors.
func fileExists(filename string) bool {
    info, err := os.Stat(filename)
    if os.IsNotExist(err) {
        return false
    }
    return !info.IsDir()
}

check if a file exists before using it

Related Posts

Image of Author Edd Turtle

Author:  Edd Turtle

Edd is the Lead Developer at Hoowla, a prop-tech startup, where he spends much of his time working on production-ready Go and PHP code. He loves coding, but also enjoys cycling and camping in his spare time.

See something which isn't right? You can contribute to this page on GitHub or just let us know in the comments below - Thanks for reading!