Re: [Help-bash] Targeting minimal POSIX compliance

[Chet Ramey]

On 4/5/18 10:58 AM, Joel Ebel wrote:
> On Wed, Apr 4, 2018 at 4:58 PM, Chet Ramey <address@hidden
> <mailto:address@hidden>> wrote:
> 
>     On 4/4/18 4:31 PM, Joel Ebel wrote:
>     > I'm attempting to build bash for a minimal environment where I would 
> like
>     > bash to be small, fast, and with minimal dependencies, but I would like 
> to
>     > still target POSIX compliance. I had first assumed that
>     > --enable-minimal-config would still provide POSIX compliance, but I 
> noticed
>     > several features being disabled that I believe are required for POSIX
>     > compliance. Notably, job control and alias. Are there other features 
> that
>     > need to be re-enabled with --enable-minimal-config in order to achieve
>     > POSIX compliance?
> 
>     --enable-job-control
>     --enable-alias
>     --enable-readline
>     --enable-history
>     --enable-strict-posix-default
> 
>     Technically, you need history to make `fc' work. Readline is needed for sh
>     vi-mode line editing (if the implementation wants to support the Posix
>     "User Portability Utilities" option).
> 
> 
> Thanks for the quick reply.  On more consideration, this is not targeting
> interactive use, only scripts to start programs, or callouts with system()
> and popen(). Users have the option to install complete bash at /bin/bash if
> they want additional features or interactive use. In that case, I don't
> think any of these options are necessary, except perhaps
> --enable-strict-posix-default. Does that make any difference if the binary
> is installed at /bin/sh? Are any of these options likely to affect
> non-interactive use?

--enable-strict-posix-default makes the options that posix mode enables
(which happen when the shell is named `sh') the default, and enables the
xpg_echo option (which, as you can imagine, is controversial). You do
probably want aliases.

Bash doesn't really have a minimal, nothing-beyond-posix mode. It's never
been a requirement. If you want that, dash is available.

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