mode for file created by open

Sat Jun 9 07:42:59 EDT 2012

Cameron Simpson wrote:
> On 08Jun2012 14:36, Neal Becker <ndbecker2 at gmail.com> wrote:
> | If a new file is created by open ('xxx', 'w')
> | 
> | How can I control the file permission bits? Is my only choice to use chmod
> | after opening, or use os.open?
> | 
> | Wouldn't this be a good thing to have as a keyword for open? Too bad what
> | python calls 'mode' is like what posix open calls 'flags', and what posix
> | open calls 'mode' is what should go to chmod.
>> Well, it does honour the umask, and will call the OS open with 0666
> mode so you'll get 0666-umask mode bits in the new file (if it is new).
>> Last time I called os.open was to pass a mode of 0 (raceproof lockfile).
>> I would advocate (untested):
>> fd = os.open(...)
> os.fchmod(fd, new_mode)
> fp = os.fdopen(fd)
>> If you need to constrain access in a raceless fashion (specificly, no
> ealy window of _extra_ access) pass a restrictive mode to os.open and
> open it up with fchmod.
>> Cheers,

Doesn't anyone else think it would be a good addition to open to specify a file 
creation mode? Like posix open? Avoid all these nasty workarounds?