Feature request: add umask (or os.umask) command

[mdekstrand]

It would be very useful to be able to set the process umask. Tcl doesn't provide this; there is an extension in TclX that does.

It seems that putting it in the posix extension would make sense to me.

[msteveb]

I can see that it would be useful. How would it interact with os.fork and exec?
What about file tempfile?

I would consider a patch, but I don't expect to get to this any time soon

[mdekstrand]

For fork and exec — the umask should be inherited by child processes.

For file tempfile — it would inherit whatever behavior the underlying system calls have with respect to umask. If it's open, the umask will be used to determine the tempfile permissions, unless additional logic is added to change that. I expect just letting the default POSIX umask behavior take effect would be the least surprising for users of the command.