How's using FileAttributeKey.posixPermissions different from using stat -f %A?

Question

I'm trying to get the posix permissions of a file, but when I use the key FileAttributeKey.posixPermissions (originally NSFilePosixPermissions) to retrieve the numerical posix permissions value, it returned 511 (-r-x--x--x), but when I use stat -f %A /path/to/file in Terminal, it returned 777 (-rwxrwxrwx) which is the correct one (I used chmod 777 /path/to/file, so it should be 777 (-rwxrwxrwx)).

This is my code using FileAttributeKey.posixPermissions (Swift 4):

var numericalValue = "000"
if let attributes = try? FileManager.default.attributesOfItem(atPath: "/path/to/file") {
    if let posixPermissions = attributes[.posixPermissions] as? NSNumber {
        numericalValue = posixPermissions.stringValue
    }
}

I don't know what is going on, I'm wondering how is the value returned from FileAttributeKey.posixPermissions different from the output of stat -f %A /path/to/file or stat -x /path/to/file, can anyone please help me to figure out?

Answer 1

You need to display the result in octal:

if let attributes = try? FileManager.default.attributesOfItem(atPath: "/path/to/file") {
    if let posixPermissions = attributes[.posixPermissions] as? NSNumber {
        let octal = String(posixPermissions.intValue, radix: 8, uppercase: false)
        print(octal)
    }
}