[geos-devel] [GEOS] #1015: Update geos-config tool for consistency

[Greg Troxel]

Mike Taves <mwtoews at gmail.com> writes:

> On Tue, 18 Feb 2020 at 13:20, Greg Troxel <gdt at lexort.com> wrote:
>> "GEOS" <geos-trac at osgeo.org> writes:
>> >  **Specify bash, and use printf to escape paths (if needed)**
>> >
>> >  This allows installation with CMake to other directories, such as `/opt/my
>> >  prefix`, since `geos-config --prefix` would return `/opt/my\ prefix`. Also
>> >  `printf` is a bash-only feature.
>>
>> It really seems like a regresssion to require bash, rather than POSIX
>> shell, and it's definitely a regression if the build doesn't find bash
>> and substitute in the path.
>>
>> Is this really necessary?
>
> As noted above, the printf function is built-in with Bash, and can
> properly escape a path. While I see there is also /usr/bin/printf I'm
> not sure how common or standard this tool is (my tests with /bin/sh
> didn't go well, so I opted to switch to Bash for reliability).

First, to me requiring bash is worse than telling people not to do
ridiculous things like putting spaces in pathnames :-)  But I realize
other people think spaces in pathnames is an ok thing.

The right question about tools is not what's typically on Linux but what
POSIX requires.

In searching for the POSIX printf spec, I found this post about escaping
spaces in a portable manner.

  https://stackoverflow.com/questions/12162010/posix-sh-equivalent-for-bash-s-printf-q

The specs at opengroup.org seem hard to deal with today - not sure if
they changed - but I found this POSIX printf description:

  https://www.unix.com/man-page/POSIX/1posix/printf/

> Currently, other Bash scripts are present in tools/ci/ but these are
> not installed with GEOS.

ci tools are quite a different story than a requirement for regular
installs, although I see using bash there (vs /bin/sh) as a bug also.

> Besides Native Windows, what OSes (that GEOS is used on) does not have
> Bash available? As far as I know, it's available on most Linux
> distributions, all recent Solaris and macOS, and even some Windows. I
> can't think of any other shell that is more common.

The shell that is more common is the one required by POSIX: /bin/sh,
having the behavior specified by POSIX.   Bash either conforms to POSIX
or is close enough, so code written for POSIX will work fine with bash.  

None of the BSDs have bash by default.  When it is present, via ports,
pkgsrc, etc., it's not in /bin.  On NetBSD, it's in /usr/pkg/bin/bash.
People use it for their login shell.  I do too - I'm not a bash hater,
but object to it for programming use.  It's enormous, and is one
particular implementation among many.  I view it as personal choice to
use it for interactive use, and not appropriate for scripting.

The fact that /bin/bash does not exist on *BSD, and probably other
places, prompted my question about looking for it and substituting the
path.  Expecting bash to be in /bin/bash is just not a valid assumption.


So, given that there seems to be a way to do this without introducing a
dependenchy on bash, I'd like to see this backed out.