os.mkdir and mode

[Nick Craig-Wood]

vj <vinjvinj at gmail.com> wrote:
>  How do I do the following unix command:
> 
>  mkdir -m770 test
> 
>  with the os.mkdir command. Using os.mkdir(mode=0770) ends with the
>  incorrect permissions. 

You mean :-

$ python -c 'import os; os.mkdir("test", 0770)'
$ stat test/
  File: `test/'
  Size: 4096            Blocks: 8          IO Block: 4096   directory
Device: 806h/2054d      Inode: 2453906     Links: 2
Access: (0750/drwxr-x---)  Uid: (  518/     ncw)   Gid: (  518/     ncw)
Access: 2006-12-02 09:42:59.000000000 +0000
Modify: 2006-12-02 09:42:59.000000000 +0000
Change: 2006-12-02 09:42:59.000000000 +0000

vs

$ rmdir test
$ mkdir -m770 test
$ stat test/
  File: `test/'
  Size: 4096            Blocks: 8          IO Block: 4096   directory
Device: 806h/2054d      Inode: 2453906     Links: 2
Access: (0770/drwxrwx---)  Uid: (  518/     ncw)   Gid: (  518/     ncw)
Access: 2006-12-02 09:43:23.000000000 +0000
Modify: 2006-12-02 09:43:23.000000000 +0000
Change: 2006-12-02 09:43:23.000000000 +0000
$ umask
0022
$

So it looks like python mkdir() is applying the umask where as
/bin/mkdir doesn't.  From man 2 mkdir

       mkdir() attempts to create a directory named pathname.

       The  parameter mode specifies the permissions to use. It is modified by
       the process's umask in the usual way: the permissions  of  the  created
       directory  are  (mode & ~umask & 0777).  Other mode bits of the created
       directory depend on the operating system.  For Linux, see below.

So python follows C rather than shell.  Seems reasonable.

To fix your problem, reset your umask thus :-

$ rmdir test
$ python -c 'import os; os.umask(0); os.mkdir("test", 0770)'
$ stat test
  File: `test'
  Size: 4096            Blocks: 8          IO Block: 4096   directory
Device: 806h/2054d      Inode: 2453906     Links: 2
Access: (0770/drwxrwx---)  Uid: (  518/     ncw)   Gid: (  518/     ncw)
Access: 2006-12-02 09:48:04.000000000 +0000
Modify: 2006-12-02 09:48:04.000000000 +0000
Change: 2006-12-02 09:48:04.000000000 +0000
$

-- 
Nick Craig-Wood <nick at craig-wood.com> -- http://www.craig-wood.com/nick