Re: Bash silently exits where attempting to assign an array to certain built-in variables using declare

[Chet Ramey]

On 6/29/23 9:38 AM, Kerin Millar wrote:
> On Thu, 29 Jun 2023 08:51:58 -0400
> Chet Ramey <chet.ramey@case.edu> wrote:
>
> > On 6/28/23 1:14 PM, Kerin Millar wrote:
> > > This report is based on an observation made within the depths of this thread: 
> > > https://lists.gnu.org/archive/html/bug-bash/2023-06/msg00094.html.
> > >
> > > Attempting to assign an array to any of the following variables with the 
> > > declare builtin causes bash to immediately exit with no diagnostic message 
> > > being issued.
> > >
> > >     BASH_ARGC
> > >     BASH_ARGV
> > >     BASH_LINENO
> > >     BASH_SOURCE
> > >     GROUPS
> >
> > These are all `noassign' variables; assignments to them are ignored.
> > The bash debugger variables cannot be unset either. Other noassign
> > variables can be unset; that's why they're not readonly.
> >
> > (Before you ask, noassign variables have been in bash since 1996.)
>
> Thanks for this information. While I had no expectation of them being 
> assignable, some of this might have a valid place in the manual.

Agreed.


> > > It does not happen if trying to assign a string.
> >
> > It should be consistent, at least. I think the string assignment behavior
> > is the most reasonable: assignments return 1 but there's no assignment
> > error. I'll look at how compound assignments are different.
>
> Thanks. I would just add that 'noassign' variables are not consistently indicated in the 
> manual. For example, it is said for GROUPS that "Assignments to GROUPS have no 
> effect" but there is no such wording for the others that I mentioned. That might be 
> worth addressing, even if only by inserting similarly worded sentences where appropriate.

Agreed; the latest devel branch push added that wording for the debugger
variables.

Chet
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/