Subject: Re: VERY strange command-line syntax for 'df -t'
To: NetBSD Userlevel Technical Discussion List <tech-userlevel@NetBSD.ORG>
From: Greg A. Woods <email@example.com>
Date: 04/08/2002 19:02:09
[ On Monday, April 8, 2002 at 21:20:05 (+0100), David Laight wrote: ]
> Subject: Re: VERY strange command-line syntax for 'df -t'
> On Mon, Apr 08, 2002 at 01:08:33PM -0400, Greg A. Woods wrote:
> > 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'.
Not true, at least not for the case where other operands are given.
The main point though is to not optimise the logic into obscurity and
not to make it new, unique, and different from everything else that
looks the same. K.I.S.S. As I pointed out mount(8) already uses syntax
of the kind I proposed to toggle flags -- using the same syntax in two
completely opposing ways all within the same command is, well, "less
than ideal" to say the least.
The secondary point is of course to be able to get the warning (at least
for 'df', and maybe the others too, i.e. 'fsck' and 'mount') when other
operands are given.
> Without a 'no', the list means 'only process the specified filesystems'.
> With a 'no', the list means 'process all but the specified filesystems'.
That's the current implementation -- not what I proposed. Please try to
keep these things separate.
> A bit of logic shows that once you have specified the 'only', 'all but'
> doesn't restrict things further...
I've said this same thing several times already and shown several ways
why it's undesirable to be so persnickety about refining the syntax down
to the absolute bare minimum. Please re-read my original posting again,
Greg A. Woods
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