DOS filesystems and access permissions

Only root and users with Administer Filesystems authorization can mount filesystems, including DOS filesystems.

A user's access to a mounted DOS filesystem is determined by the permissions and ownership that root places on the filesystem.

When DOS files are mounted on a UNIX system:

• The permissions and ownership of the filesystem are determined by the permissions of the mount point.

  For example, if root creates a mount point /x with permissions of 0777, all users can read or write the contents of the filesystem. If the mount point is owned by root, all files in the DOS filesystem and any created by other users are owned by root.

• The permissions for regular files on the mounted DOS filesystem are set to either 0777 (for readable/writable files) or 0555 for read-only files.

• The permissions are based on the umask(1) of the creator when a user creates a file on a mounted DOS filesystem.

  For example, if a user's umask is 0022, all files created by that user have permissions of 0644.

• Files in a DOS filesystem cannot have multiple links.

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  NOTE: ``.'' and ``..'' are special cases; on a mounted DOS filesystem, they are not links as they are on a UNIX system.

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• Features such as locking govern how different users can access a file simultaneously on UNIX systems. These features operate identically on a mounted DOS filesystem. Two users can edit the same file and write to it as permitted by the locking mechanism used.