Re: [docs] [bitbake-devel] [PATCH] doc: Mention `if [[ somecondition ]]` is not supported

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Tue, 2025-03-25 at 11:04 +0100, Quentin Schulz via lists.yoctoproject.org wrote:
> 
> 
> On 3/20/25 1:33 AM, Javier Tia via lists.openembedded.org 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.
> > +
> 
> Do you know what the reason is for that limitation?
> 
> The example above this git context is not really implying `[[ 
> somecondition ]]` would be valid though.
> 
> If I remember correctly, the shell functions are run by /bin/sh 
> interpreter, so it depends on which shell you have configured by default 
> in your system. Is it possible this is due to you being used to develop 
> with bash where this is possible and having your Yocto build run with a 
> different shell (e.g. dash, which doesn't seem to support that? c.f. 
> https://manned.org/dash.1)?
> 
> I think we should recommend people write POSIX-compliant shell functions 
> and tasks rather no?

Bitbake parses the shell functions and our shell parser can't cope with
certain syntax unfortunately.

Cheers,

Richard