Shows what they know.  File permission bits and umask are in fact supported in the Win32 API, but the only meaningful bit is the user-write bit (this dates back to MS-DOS days when files could be read/write or read-only).  It's true that most permissioning is done by the ACL, of course.  Cygwin has a whole set of logic for mapping Posix permissions onto Windows. and supports the umask in its shim layer.

I am reasonably sure that the u in umask stands for the old Unix kernel's u area, a part of the per-process state that could be swapped out with a process because it was only needed when the process was actually running.  The C struct for this was struct user { ... } even though it was per-process and not per-user.

On Wed, Apr 29, 2020 at 5:50 AM Lassi Kortela <> wrote:

Q: What is the Windows/ Windows Storage server equivalent of a umask?

A: I'm not aware of a direct equivalent; NTFS permissions are
hierarchical in general, so you should be looking at changing the ACLs
on the parent directory, possibly involving CREATOR_OWNER depending on
what you want to do.

A: There is none. In Windows, new files and folders will inherit the
permissions of the directory that they are originally created in.

A: The equivalent would be inheritance. Set the permissions on a parent