bug#7042: df --help does not show `-m' option

[Eric Blake]

On 09/16/2010 09:20 AM, Pádraig Brady wrote:
> On 16/09/10 12:59, Petr Pisar wrote:
> > Hello,
> >
> > I found `df' utility from coreutils-8.5 does not describe `-m' option that is
> > mentioned in info page and the program accepts it.
> >
> > -- Petr
>
> -m was deprecated in 2001
> http://git.savannah.gnu.org/gitweb/?p=coreutils.git;a=commit;h=d1772031
>
> It is not mentioned in the info page as far as I can see
> It's not specified by POSIX
> It's not used in solaris
> It _is_ used in FreeBSD

Oh - I only tested MirBSD (which is more like OpenBSD).

> So this is much the same argument as supporting `dd bs=1m`
> http://lists.gnu.org/archive/html/coreutils/2010-09/msg00028.html
>
> Also there was a previous request for `df -g` and `du -g`
> http://lists.gnu.org/archive/html/bug-coreutils/2009-12/msg00000.html

Yeah, the 'existing implementation' argument does carry some weight 
(then again, witness my patch today to nuke 'rm -d' even though that was 
also based on the 'existing implementation' argument).

> The only reason one would support these is for compat with FreeBSD,
> and if we did, we wouldn't want to promote their use through documentation.

Or, maybe what we should do is:

now:
make 'du--megabytes' issue a warning (it is the wrong word for what it 
does).
document -m, with --block-size=M as the long-option spelling
add -g, with --block-size=G as the long-option spelling

in a few years:
remove 'du --megabytes' altogether

--
Eric Blake   address@hidden    +1-801-349-2682
Libvirt virtualization library http://libvirt.org