2021-11-03 17:06:07 +0100, Vincent Lefevre via austin-group-l at The Open Group:
> On 2021-10-30 14:33:04 +0100, Stephane Chazelas via austin-group-l at The
> Open Group wrote:
> > POSIX ended up mandating that bug (mandating that system("+c")
> > should run an interactive shell for instance), because, like the
> > the Unix libc implementors, they overlooked the issue. It is
> > clearly a bug in the standard.
>
> It doesn't mandate that system("+c") should run an interactive shell.
Yes, I agree it looks like the behaviour of sh -c +c is
unspecified.
[...]
> ksh93 and mksh run an interactive shell, but I wonder whether this
> should be regarded as a bug.
>
> The sh utility has the following in SYNOPSIS:
>
> sh −c [−abCefhimnuvx] [−o option]... [+abCefhimnuvx] [+o option]...
> command_string [command_name [argument...]]
>
> i.e. "+c" doesn't seem to be allowed to "cancel" the "-c".
[...]
I can't see why that wouldn't be allowed as an extension.
Just like bash's
sh -c +O xpg_echo 'echo -e "\b\c"'
would be allowed as an extension (and not be required to
interpret the +O script with xpg_echo in $0 and echo -e "\b\c"
in $1).
As the -O / +O option is not among the options POSIX specifies.
--
Stephane
