Re: Identifying the NetBSD shell

[Paul Goyette <paul%whooppee.com@localhost>]

On Mon, 21 Mar 2016, Robert Elz wrote:

> I sent a message to tech-userlevel a week or so ago, asking about a few
> things that I was considering changing in NetBSD's sh (which can't be
> categorised really as being bug fixes), but got no response...
>
> For some of them, that's no great surprise, they are fairly minor, and
> of little consequence.
>
> But for one, I would really like to hear some opinions, and not just
> do whatever I think is best, and then get complaints later...
>
> Most shells (but not all, and the "not" currently includes NetBSD's shell)
> have some internal pre-defined variable (that is, can be used in scripts as
> $VAR - I am not talking about the C code) which can be used to identify the
> shell that is in use.
>
> Bash has BASH and BASH_VERSION (and more) ksh has KSH_VERSIOn, zsh has a whole
> bunch of ZSH_* vars.
>
> I want to do a similar thing for NetBSD's sh.   That leads to two questions.
>
> 1) what name should the variable have?   (I am currently using NBSD_SHELL,
> but there is no particular importance in that name.)

Given the (very) slight preponderence above for xxx_VERSION, why not use 
NBSD_VERSION?

> 2) what value should it have?   I am expecting it will be a read-only var.

Hmmm.  Start with "1.0" and increment when "appropriate"?

> There is not much more to say about Q1, provided the name meets the sh
> var name syntax rules, anything goes...
>
> For 2, I would like to include some version identification (and possibly
> simply be that version info).

The shell version should/would be separate from system version, right? 
We can always use uname(1) for OS version.

Sidebar:  perhaps the shell version could be used as a proxy for the 
"userland version" to detect userland/kernel mismtaches?

> Currently, the NetBSD shell is just "it", it has no name (but sh) and
> no version info (other than "the sh in NetBSD 7.0" or "the sh from current
> as of 2016-03-21" or something.
>
> When the current round of improvements are done, I'd like to put the NetBSD
> shell in pkgsrc/shells so others can get the benefits of what is becoming
> quite a good shell I think - and for that (to be easy to maintain anyway)
> we also need a version numbering scheme.
>
> What I am thinking for this, is that we create 3 segment version numbers,
> N.M.P where "N.M" is the netbsd release the shell started at (so the
> NetBSD 7.0 shell would have had N=7 and M=0 had this scheme existed when
> it was released.  P is to be a patchlevel counter that gets incremented
> whenever there are changes made that are significant enough to warrant
> calling it a new version - and certainly every time a new vresion is
> released to pkgsrc).   Just like NetBSD version numbers, M==99 implies
> "current" on he way to version N+1.   Note that P in the shell version
> numbering would have no relationship at all with the third value in
> NetBSD version numbers, so NetBSD 7.0.1 7.0.2 ... would all just have a
> "7.0.P" shell version number, with whatever value is appropriate for P
> (possibly all just 0).
>
> For now, I am using 7.99.1 as my version number - as I am doing all of
> this to the NetBSD current (7.99) shell, and 7.99.0 would be the shell
> that is there immediately before this version number shceme is implemented
> (and all previous versions... there have been many recently.)
>
> for reference, using my current version of NetBSD's sh (not yet available
> anywhere but on my laptop) I get ...
>
> 		$ echo $NBSD_SHELL
> 		7.99.1
> 		$
>
> So, I am seeking opinions, is all of this reasonable, what name should be
> used, and what value (and about the version numbering scheme in general?)
>
> kre
>
> ps: whatever is decided for this (other than "forget it") I expect to be
> a permanent change, I don't think we should implement and release one thing
> only to change it a month or two (or more) later.   Once released, that will
> be it, so get your opinions in before that happens.
>
>
> !DSPAM:56ef954d25218757515768!

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