How to create a directory that has specific permissions

Question

I'm trying to create a directory in Go with very specific permissions. I need drwxrwxr-x but I don't know how to do it with os.Mkdir(). I've tried os.ModeDir, os.ModePerm and os.ModeSticky

I'm on linux and I do not care if the solution will work in windows. it can, but it doesn't have to.

My issue is that I'm trying to create a directory that is later used within the program itself (the program creates the directory and it uses it to write files to).

also, most tutorials online suggest os.ModePerm but it results in ```d---------``` and I cannot write to the directory — kamkow1, Sep 05 '22 at 18:18
Does this answer your question? [os.Mkdir and os.MkdirAll permissions](https://stackoverflow.com/questions/14249467/os-mkdir-and-os-mkdirall-permissions) — Bartosz Grzybowski, Sep 05 '22 at 18:25

Spencer Connaughton · Accepted Answer · 2022-09-05T19:32:33.127

To quote https://stackoverflow.com/a/59963154/1079543:

all programs run with a umask setting...the set of permissions that the system will automatically remove from file and directory creation requests.

Setting the umask to 0 when you start the program produces the result you're looking for:

//go:build unix
package main

import (
    "log"
    "os"

    "golang.org/x/sys/unix"
)

func main() {
    unix.Umask(0)
    if err := os.Mkdir("dirname", 0775); err != nil {
        log.Fatalf("failed to create directory: %v", err)
    }
}

//go:build unix should be true "if GOOS is a Unix or Unix-like system" per: https://pkg.go.dev/cmd/go#hdr-Build_constraints

The old way to do this was with syscall.Umask(0). This package is now deprecated per: https://go.googlesource.com/proposal/+/refs/heads/master/design/freeze-syscall.md

How to create a directory that has specific permissions

1 Answers1