Subject: Re: VERY strange command-line syntax for 'df -t'
To: NetBSD Userlevel Technical Discussion List <tech-userlevel@NetBSD.ORG>
From: David Laight <>
List: tech-userlevel
Date: 04/08/2002 21:20:05
On Mon, Apr 08, 2002 at 01:08:33PM -0400, Greg A. Woods wrote:
> Do you mean within the context of my proposal, or in the current
> implementation?  I.e. do you really mean:
> 	-t mfs,nonfs

that's the one.....
> > Since file systems types don't overlap, if you explicitly include
> > one file systems type you implicitly exclude all others.
> I discussed this already, but perhaps not in enough detail.
> What about if other command-line operands imply a default list of
> filesystems which is a subset of the complete list?
> What about this documented behaviour (from df(8))?
>       If a file system is given on the command line that is not of the
>       specified type, a warning is issued and no information is given on
>       that file system.
> Under my proposal I would expect your example to generate a warning if
> no "mfs" filesystems are mounted (and no files are specified on the
> command line).

Indeed, what I meant was that once you have specified 'mfs' then
'nonfs' is implicitely implied because '-t mfs' means 'only process
mfs filesystems'.

Without a 'no', the list means 'only process the specified filesystems'.
With a 'no', the list means 'process all but the specified filesystems'.
A bit of logic shows that once you have specified the 'only', 'all but'
doesn't restrict things further...


David Laight: