Subject: Re: Improving the Unix API
To: Francois-Rene Rideau <>
From: Werner Almesberger <>
List: tech-kern
Date: 06/27/1999 14:46:13
Francois-Rene Rideau wrote:
> Robert told me that in some Unix flavors of old,
> it was possible to open a file by path with a null access mode (O_NULL ?)

E.g. Linux. Very undocumented, but has been around for ages ('92 or
such). The main purpose is to keep the floppy drive from spinning up
to check for a media change when you open it to access parameters and
such. E.g. fdformat, setfdprm, and LILO use this. (NB: some versions
of strace print the flags argument in this case as "0x4", although
it's really 3.)

- Werner

 / Werner Almesberger, ICA, EPFL, CH /