Re: [PATCH] doc: Mention `if [[ somecondition ]]` is not supported

["Antonin Godard" <antonin.godard@bootlin.com>]

Hi Javier,

On Thu Mar 20, 2025 at 1:33 AM CET, Javier Tia wrote:
> I keep forgetting using `if [[ somecondition ]]` is not supported.
>
> Signed-off-by: Javier Tia <javier.tia@linaro.org>
> ---
>  doc/bitbake-user-manual/bitbake-user-manual-metadata.rst | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst b/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst
> index 415fbf6d6..5474e154f 100644
> --- a/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst
> +++ b/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst
> @@ -1381,6 +1381,10 @@ To make use of this technique, you need the following things in place:
>     To call your modified version of the function as defined in your recipe,
>     call it as ``do_foo``.
>  
> +   .. note::
> +
> +      Conditional expression using ``[[ somecondition ]]`` is not supported.
> +
>  With these conditions met, your single recipe can freely choose between
>  the original function as defined in the class file and the modified
>  function in your recipe. If you do not set up these conditions, you are

The documentation already says the following:

  The scripts are executed by ``/bin/sh``, which may not be a bash
  shell but might be something such as ``dash``. You should not use
  Bash-specific script (bashisms).

I think [[ ]] is a bashism, or at least the POSIX shell spec clearly state to
not use it[1]. I'm not sure the BitBake documentation should list all the shell
syntax it does not support, as I expect there are quite a few.

The codeparser, however, could be modified to try and detect the usage of [[ ]]
and give a warning on such occurrences?

[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_04

Antonin

-- 
Antonin Godard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com