severity 587741 wishlist
tags 587741 + upstream wontfix
quit
Hi,
Thanks for writing. Here is an explanation by Jilles Tjoelker. Sorry we
did not cc you on this before:
> In your example
> $ dash -c 'noop(){ true;}; x=1; noop; x=broken noop; echo "x is now $x"'
> x is now broken
> dash's behaviour is what POSIX requires, and the same can be seen with
> bash --posix and ksh93. The relevant section is XCU 2.9.5 Function
> Definition Command.
>
> The same thing applies to special builtins such as ':', exec and unset.
> For example, these two both print 'good':
> dash -c 'x=bad; x=good :; echo $x'
> dash -c 'x=good; x=bad true; echo $x'
> Again bash needs --posix here.
>
> The idea behind special-casing some of the builtins is that the special
> builtins must always be builtins and are treated like how the original
> Bourne shell treated all builtins, while all other utilities may be
> implemented as builtins or external programs and are treated like how
> the original Bourne shell treated external programs (except that some of
> them affect the shell environment in a way only a builtin can).
>
> There is less historical basis for the treatment of assignments on
> function calls, as such assignments had no effect whatsoever in the
> original Bourne shell.
I'm keeping the report as a reminder to document it, but this behavior
in dash is not likely to change unless POSIX changes (see
http://www.opengroup.org/austin/ if you would like to work on that).
Thanks,
Jonathan
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