On 04/14/2014 11:53 AM, Doug Hellmann wrote:
As someone who maintains a shell-script project across several
"sh-like" shells, I can say the edge cases cause enough work and
testing hassles that you shouldn't undertake it lightly. Is there any
particular need to run these tools under a non-bash shell?
I don't have one, but I've seen a few changes proposed to make the
scripts work with other shells (although in at least one case I believe
it was in a script explicitly using bash, so I'm not sure what the
purpose was...). And those edge cases are why I would like to stop
trying to support not-bash unless someone else wants to step up and own
that effort.
Thanks for the input.
-Ben
Doug
On Mon, Apr 14, 2014 at 12:26 PM, Ben Nemec <openst...@nemebean.com> wrote:
tldr: I propose we use bash explicitly for all diskimage-builder scripts (at
least for the short-term - see details below).
This is something that was raised on my linting changes to enable set -o
pipefail. That is a bash-ism, so it could break in the diskimage-builder
scripts that are run using /bin/sh. Two possible fixes for that: switch to
/bin/bash, or don't use -o pipefail
But I think this raises a bigger question - does diskimage-builder require
bash? If so, I think we should just add a rule to enforce that /bin/bash is
the shell used for everything. I know we have a bunch of bash-isms in the
code already, so at least in the short-term I think this is probably the way
to go, so we can get the benefits of things like -o pipefail and lose the
ambiguity we have right now. For reference, a quick grep of the
diskimage-builder source shows we have 150 scripts using bash explicitly and
only 24 that are plain sh, so making the code truly shell-agnostic is likely
to be a significant amount of work.
In the long run it might be nice to have cross-shell compatibility, but if
we're going to do that I think we need a couple of things: 1) Someone to do
the work (I don't have a particular need to run dib in not-bash, so I'm not
signing up for that :-) 2) Testing in other shells - obviously just changing
/bin/bash to /bin/sh doesn't mean we actually support anything but bash. We
really need to be gating on other shells if we're going to make a
significant effort to support them. It's not good to ask reviewers to try
to catch every bash-ism proposed in a change. This also relates to some of
the unit testing work that is going on right now too - if we had better unit
test coverage of the scripts we would be able to do this more easily.
Thoughts?
Thanks.
-Ben
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