bug#79113: du --time-styles inconsistencies between manual and behaviour

On Tue, 29 Jul 2025 at 00:07, Pádraig Brady <[email protected]> wrote:
>
> tag 79113 notabug
> close 79113
> stop
>
> On 28/07/2025 15:44, Nicolas Boichat wrote:
> > Hi,
> >
> > Version: env du --version => du (GNU coreutils) 9.7
> > OS: archlinux, x86-64
> >
> > The GNU coreutils manual says
> > (https://www.gnu.org/software/coreutils/manual/coreutils.html#index-_002d_002dtime_002dstyle-1):
> > - "You can specify the default value of the --time-style option with
> > the environment variable TIME_STYLE; if TIME_STYLE is not set the
> > default style is ‘long-iso’." -> yes
> > - "For compatibility with ls, if TIME_STYLE begins with ‘+’ and
> > contains a newline, the newline and any later characters are ignored;"
>
> Copying the full docs for this from the texinfo:
>
>    "You can specify the default value of the @option{--time-style} option
>    with the environment variable @env{TIME_STYLE}; if @env{TIME_STYLE} is not set
>    the default style is @samp{long-iso}.  For compatibility with @command{ls},
>    if @env{TIME_STYLE} begins with @samp{+} and contains a newline,
>    the newline and any later characters are ignored; if @env{TIME_STYLE}
>    begins with @samp{posix-} the @samp{posix-} is ignored; and if
>    @env{TIME_STYLE} is @samp{locale} it is ignored."
>
> That quite clearly states the above compat handling
> is for the TIME_STYLE env var, and not the --time-style option itself.

Oh, thanks, I obviously misread that and the intent. Makes sense, thanks.

> >
> > That does not match behaviour, newlines are just used as-is:
> > ```
> > $ env du --time --time-style="$(printf "+xyz\nabc")" blob
> > 96 xyz
> > abc blob
> > ```
>
> > Finally, the help text doesn't mention that +FORMAT is allowed.
>
> Copying from the texinfo again:

I could have been clearer for this last one, I mean that the command
line error text for `du` could mention that +FORMAT is supported:

Comparing du and ls output with a bad timestyle:
```
$ du --time --time-style=xyz blob
du: invalid argument ‘xyz’ for ‘time style’
Valid arguments are:
  - ‘full-iso’
  - ‘long-iso’
  - ‘iso’
>>>>> it would be nice to add `- +FORMAT (e.g., +%H:%M) for a 'date'-style format` here
Try 'du --help' for more information.
$ ls -l --time-style=xyz blob
ls: invalid argument ‘xyz’ for ‘time style’
Valid arguments are:
  - [posix-]full-iso
  - [posix-]long-iso
  - [posix-]iso
  - [posix-]locale
  - +FORMAT (e.g., +%H:%M) for a 'date'-style format
Try 'ls --help' for more information.
```

Thanks,