Bug#490604: debian-policy: please don't state that scripts working under dash are 'probably' policy-compliant

[Jonathan Nieder <jrnieder@gmail.com>]

Russ Allbery wrote:

> I think checkbashisms and posh are an improvement over just suggesting
> bash (and checkbashisms, in particular, is much easier to use), so my
> inclination is to stick with the new wording and leave the further details
> for other tools.

I assume by 'bash' you mean 'dash' above.

I certainly didn't mean to suggest including a full list in policy.
What I was worried about is that people will follow the following
process:

  no checkbashisms warnings?
  can posh handle it?
  ok, I'm done.

while the following has worked better for me:

  can dash handle it?
  can ksh88 handle it? (alas, not in Debian)
  ok, I'm done.

and the following is ideal:

  no checkbashisms warnings?
  can all (6?) shells in Debian that are policy-compliant as /bin/sh
   handle it?
  ok, I'm done, until someone files a bug report.

The test is easier to carry out once the target of /bin/sh is allowed
to vary among more shells.  Currently bash and dash are the only link
targets that can be chosen using packages from sid without the symlink
being overwritten by upgrades.

I would prefer a less specific note:

	Checking your script with checkbashisms from the devscripts
	package or running your script with an alternate shell such as
	posh may help uncover violations of the above requirements.