Linux – No effect of umask and chmod on mounted drives

chmodlinuxumask

The windows drives are mounted at boot-time using pysdm. The setting were

nls=iso8859-1,users,umask=002,sync,user,dirsync,uid=mtk

When I try to change the permission of files using chmod, I don't see any update in the permissions. Chmod quietly returns the prompt. Also the permission of created files must have been 755 instead of 775. Here is the output of terminal.

mtk@mtk-laptop$ umask
0022
mtk@mtk-laptop$ touch abc.txt
mtk@mtk-laptop$ ls -l abc.txt 
-rwxrwxr-x 1 mtk root 0 May 14 00:00 abc.txt*
mtk@mtk-laptop$ chmod ugo-x abc.txt 
mtk@mtk-laptop$ ls -l abc.txt 
-rwxrwxr-x 1 mtk root 0 May 14 00:00 abc.txt*
mtk@mtk-laptop$

Does anyone know what is the issue behind this?

I am using ubuntu 12.04.

Best Answer

Unix permissions don't apply to and can't be mapped to Windows permissions, so chmod is necessarily a no-op. (FAT doesn't have permissions at that granularity, and NTFS permissions are stored not by username or numeric ID but by a UUID that Linux has no access to.) The permissions you see are manufactured by the umask=002 part of the mount options.

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