Samba and ShellCheck

[Christof Schmitt]

On Tue, Aug 23, 2022 at 06:02:43PM +1000, Martin Schwenke via samba-technical wrote:
> Hi Andreas,
> 
> On Tue, 23 Aug 2022 07:50:24 +0200, Andreas Schneider via
> samba-technical <samba-technical at lists.samba.org> wrote:
> 
> > for Samba master we have ShellCheck with error level in place now. It will 
> > check that our scripts are error free!
> 
> Yay!
> 
> That probably isn't true for CTDB, but we are gradually improving things.
> 
> > The next step would be to move ShellCheck to warning level and this will be 
> > quite some work.
> 
> Yep!
> 
> > But first we need to discuss something.
> > 
> > If I run ShellCheck in warning level:
> > 
> > ./script/check-shell-scripts.sh $(pwd) warning
> > 
> > The warning I see most of the time is:
> > 
> > warning: In POSIX sh, 'local' is undefined. [SC3043]
> 
> This is why I never use local in /bin/sh scripts.  It has never made it
> into POSIX.  I suspect the reason is that different shells implemented
> different semantics.  For example:
> 
>   local foo=$(example --command)
> 
> I think local in bash eats the exit code of the subshell.  Other shells
> may implement it differently.
> 
> I use an "excellent" convention for local variables in /bin/sh scripts,
> specially designed to reduce readability.  ;-)  I prefix any local
> variable with '_'.  However, it makes no semantic difference, it just
> acts as a hint.
> 
> > Why do do we use POSIX shell (#/bin/sh) for the majority of our tests (we also 
> > have scripts with #!/bin/bash)?
> 
> For portability.  I would encourage anyone writing scripts that do not
> need bash features to use /bin/sh instead.
> 
> In CTDB we have switched our bash scripts (we definitely have some)
> to use
> 
>   #!/usr/bin/env bash
> 
> so they have a chance of working on platforms without /bin/bash.

Would it be worthwhile to capture the outcome of this discussion in
README.Coding and somewhere under
https://wiki.samba.org/index.php/Developer_Documentation ?

Christof