bug#10915: 8.13: df -- overly long output lines are very hard to read

[Jim Meyering]

Voelker, Bernhard wrote:
> Jim Meyering wrote:
>> jaalto wrote:
>
>> | >         -r, --reverse
>> | >
>> | >     $ df -Hlr
>> | >
>> | >     Size  Used Avail Use% Mounted-on Filesystem
>> | >     6.0G  4.1G  1.7G  72% /             rootfs
>> | >     192M     0  192M   0% /dev          udev
>> | >      40M  1.5M   38M   4% /run          tmpfs
>> | >     6.0G  4.1G  1.7G  72% /             
>> /dev/disk/by-uuid/492764a5-7506-4489-8fd0-82d0d284d627
>> | >     5.3M     0  5.3M   0% /run/lock     tmpfs
>> | >      79M  7.9M   71M  10% /tmp          tmpfs
>> | >      79M     0   79M   0% /run/shm      tmpfs
>> | >     6.0G  4.1G  1.7G  72% /srv/cante.src 
>> /dev/disk/by-uuid/492764a5-7506-4489-8fd0-82d0d284d627
>> | >     6.0G  4.1G  1.7G  72% /srv/cante.tmp 
>> /dev/disk/by-uuid/492764a5-7506-4489-8fd0-82d0d284d627
>> | >      18G  8.1G  8.3G  50% /mnt/extent   /dev/sdb1
>> | >      18G  8.1G  8.3G  50% /usr/src      /dev/sdb1
>> | >      18G  8.1G  8.3G  50% /root/vc      /dev/sdb1
>
>> I agree that your --reverse (but without the short-named '-r') would
>> be a useful improvement, regardless.  That sounds reasonable for 8.16
>> is someone writes the patch.  Even without the -r, you could still
>> abbreviate the long name to "--r".
>
> What about a more general --fmt (or --format) option to
> just get the columns you want in the order you want?
> E.g.
>
>   df --format=size,free%,mnt,fs
> or
>   df --format=size-h,mnt  # <column name>-h or
>   df --format=Size,mnt    # uppercase Size meaning -h

Good point about the name.
However, a --format=SPEC normally contains %-directives
(find, stat, and of course printf), which would make it a bigger change.
That sounds like the right course, but now, probably better to target 8.17.