bug#37702: Suggestion for 'df' utility

[Assaf Gordon]

Hi all,

On 2019-10-13 2:27 p.m., Paul Eggert wrote:
> On 10/13/19 2:41 AM, Pádraig Brady wrote:
> > I wonder could we key (also) on used==0||available==0.
>
> Yes, looking at the sample output I gave earlier, I'd say we could by 
> default drop filesystems where usage is 1% or less. That would solve the 
> problem for my workstation. This is roughly akin to the "used==0" test 
> you're suggesting.

I would humbly suggest caution with such unexpected user-facing changes
to the default output of 'df' - learning the lessons from changing the 
quotes in 'ls'.

Countless users have been using 'df' in their own ways, and have gotten
used to certain outputs.

This thread originated by a request to "clean up" the output on newer
ubuntu machines which use "snap" packages as /dev/loopN .

Let's not turn that into a drastic change that will affect many other
existing systems - the users on other systems did not ask for any changes.

---

Specifically for "default drop filesystems where usage is 1% or less" -
I can think of few cases off the top of my head where this would be
extremely confusing:

- I recently installed a 33TB raid file system. The usage on that system
is at %1 and will stay like so for at least several days.

- Amazon cloud services (AWS) offers an NFS4 service (they call it 
"EFS") that has reported size of 8 exabytes. There too usage could be at 
%1 for a long long time.

---


For cases where I want to list only the "real" storage, I typically use
an alias such as:

   alias dff='df -h -x tmpfs -x devtmpfs'

And it would be very easy and least disruptive to recommend
to ubuntu users to add "-x squashfs" or another file system to ignore.


Perhaps we can come up with a recommended list of "lesser" file systems
to ignore (or conditions such as read-only file
systems) and add it as a new option, but please let's not make it the
default.



My two cents,
 - assaf