check if a file exists on the file system

check.go

// approach 1
if _, err := os.Stat("/path/to/whatever"); os.IsNotExist(err) {
	// path/to/whatever does not exist
}

// approach 2
if _, err := os.Stat("/path/to/whatever"); err == nil {
	// path/to/whatever exists
}

// equivalent to Python's `if os.path.exists(filename)`
if _, err := os.Stat(filename); err == nil {
    fmt.Printf("file exists; processing...")
    process(filename)
}