[pbs-devel] [PATCH proxmox] proxmox-router: Improve CLI text output when printing empty lists

[Laurențiu Leahu-Vlăducu]

On 24.01.25 09:26, Thomas Lamprecht wrote:
> Am 22.01.25 um 14:14 schrieb Laurențiu Leahu-Vlăducu:
>> CLI tools that use '--output-format text' and print empty lists now
>> show a 'No results' message. Previously, this was sometimes confusing
>> because nothing was printed.
> 
> I get where you come from with this but "No result" might be interpreted
> as error-like message by some though?

I am open to suggestions about the error message :) I was also not 100% 
sure what the best message could be (especially one that shouldn't sound 
like an error). I would have preferred to have something more specific 
(e.g. "No tape drives found", but since this is a general formatter, I 
cannot do that (at least not without adding additional parameters, which 
is not worth it for this use case, IMO).

> And not sure how popular such an approach is, most standard CLI tools
> do not print anything if the result is empty, e.g. `ls` on an emtpy dir
> also outputs nothing. Are there any user requests/feedback on this?

Not that I know. This was kind of my own request, because I wrote some 
docs on PBS tape backups and thought: if the user never used tape 
drives/changers and is unsure whether they have been detected correctly, 
they might try "proxmox-tape drive scan" or "proxmox-tape changer scan" 
(or "list"), and if nothing is found, there is no output. Now, if the 
user knows what the output should look like (a table with 
drives/changers), it may be obvious that an empty output means that 
proxmox-tape found nothing. But if the user never used PBS or tapes 
before, or if that happened a long time ago, it might be unclear why 
there is no output. Thus showing no output for "proxmox-tape drive scan" 
makes it unclear whether this is an error or just empty.

I agree with you that printing something like "No result" makes it 
inconsistent with other CLI tools. On the other hand, at least when 
talking about tape drives/changers that require drivers and hardware 
detection, it's nice to have some further details on what is happening 
"behind the scenes".

Another argument in favor of it is that using --output-format json or 
json-pretty also shows an empty list [], making it clearer that it's not 
an error.

Just some of my thoughts ;) I know that this is a general formatter and 
not related to proxmox-tape, but I thought it could make sense in other 
Proxmox CLI tools as well.