Re: [PATCH] Increase $COLUMNS when generating long option completions

[Lawrence Velázquez <larryv@xxxxxxx>]

> On Aug 4, 2021, at 2:53 AM, Marlon Richert <marlon.richert@xxxxxxxxx> wrote:
> On Wed, Aug 4, 2021 at 4:12 AM Lawrence Velázquez <larryv@xxxxxxx> wrote:
>> 
>> On Tue, Aug 3, 2021, at 10:05 AM, Marlon Richert wrote:
>>> On Mon, Aug 2, 2021 at 2:07 AM Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx> wrote:
>>>> I'm puzzled, doesn't this imply that the value of $COLUMNS is
>>>> incorrect on entry to the function?
>>> No, the problem results from _call_program being connected to a pipe:
>>>   _call_program $lflag options ${~words[1]} --help 2>&1 |
>>>     while IFS= read -r opt; do
>>> When ${~words[1]} is an external command, it will then not see
>>> $COLUMNS, unless $COLUMNS has been exported.
>> 
>> Isn't that the case in general?  External commands *never* see
>> COLUMNS if it isn't in the environment.  The pipe is a red herring.
>> 
>>> For example, compare the output of the following:
>>> % pip3 --help
>>> % _call_program tst pip3 --help
>>> % _call_program tst pip3 --help | cat
>>> % print -r -- "$( pip3 --help )"
>> 
>> Seems like pip is behaving differently depending on whether it's
>> outputting to a tty or not.
> 
> I feel that cannot be the whole story, because if I do any of the
> following, I get terminal-width output, instead of 80 columns:
> 
> % COLUMNS=$COLUMNS pip3 --help | cat
> % print -r -- "$( COLUMNS=$COLUMNS pip3 --help )"

Yes, these commands are explicitly setting COLUMNS in pip’s environment. As Bart said, the tty vs. not-tty distinction probably only matters when COLUMNS is not in pip’s environment.

> % _call_program tst COLUMNS=$COLUMNS pip3 --help | cat
> 
> And pip isn't the only command that works that way. For example:
> 
> % ls -x /
> Applications Library System Users Volumes bin cores dev etc home
> opt private sbin tmp usr var
> % ls -x / | cat
> Applications Library System Users Volumes
> bin cores dev etc home
> opt private sbin tmp usr
> var
> % COLUMNS=$COLUMNS ls -x / | cat
> Applications Library System Users Volumes bin cores dev etc home
> opt private sbin tmp usr var
> %

Same thing here. You are explicitly setting COLUMNS in the environment of ls, and ls is respecting it.

-- 
vq
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