Re: multi-threaded compiling

[Mischa Baars]

On Tue, Mar 12, 2024 at 8:16 AM Robert Elz <kre@munnari.oz.au> wrote:

> This whole discussuon has been a total mess.
>
> First the original message didn't give nearly enough info.
> That might have been in the attachment, but no-one should be
> expecting people to do any needless work when you're asking
> for (free) assistance - if you want help you need to make
> it as easy as possible for people to do that.
>
> Second, a very common issue with people having problems, is
> when they have a problem to solve, they work out how they think
> they should do that, and then have difficulty making one
> of the steps work.  At that point they ask how to do that
> thing, which might sometimes be very complex, even impossible.
> If the initial problem had been stated, along with the
> solution proposed, leading to the issue that's hard, then
> instead of (perhaps) wasting needless time dreaming up
> possible solutions to difficult problems, someone might
> just point out a much simpler method to solve the original
> problem, making finding a solution to the difficult issue moot.
>
> Second, the replies here have mostly been hopeless, with
> just a couple addressing real issues.
>
> Many of the initial replies totally missed that the OP
> said that the bash script in 'one' worked, and there
> was this long thread suggesting other ways to do it.
> Waste if everyone's time (even if the advice not to
> use SECONDS was probably useful).
>
> There is however no blanket rule that vars in upper case are
> reserved for the shell - posix contains a list of var
> names scripts should avoid using (unless they want some
> particular feature supported by a particular shell they
> are using - SECONDS & RANDOM are on that list).   Anything
> else is (or should be) OK to use.
>
> The issue with 'one' was that the same code did not work on
> the command line, or in a makefile.
>
> Chet explained the command line problem:
>
>     Date:        Mon, 11 Mar 2024 17:25:57 -0400
>     From:        Chet Ramey <chet.ramey@case.edu>
>     Message-ID:  <322e10a6-3808-49be-aa9d-a1d367a90572@case.edu>
>
>   | OK, here's the longer answer. When the shell is interactive, and job
>   | control is enabled, the shell prints job completion notifications to
>   | stdout at command boundaries.
>
> which is, IMO, yet another bogus bash misfeature.  That should
> happen, with the effect described, but only when PS1 is about
> to be printed - precisely so commands like the one described
> will work.   Sigh.
>
> There aren't many complaints about this misfeature of bash,
> as almost no-one writes interactive command lines where it makes
> a difference.   That doesn't mean they should not be able to.
>
>
> For the problem using make, it was suggested to explicity set
> the SHELL to use in the makefile, which is good advice when
> using shell specific features, as is being done here.
>
> But the real problem is almost certainly that the Makefile
> is attempting to pass scripts containing '$' chars to the
> shell.  '$' is interpreted by make, to send a '$' to the
> shell, it must be written as '$$'.
>
> Uhm... I think you forgot to look at the actual code in the Makefile here.
Every '$' is written as a '$$', exactly as you say it should.

>
> For problem 'two', Greg (I think it was) diagnosed the
> issue with var expansions, and field splitting - but if
> that was unknown to the OP then that OP has no business
> attempting to write any shell script (with any kind of
> variable) - get an introductory shell programming text
> and learn how it works - at least the basics.  Don't
> just guess or attempt to copy other scripts, you'll fail.
>
> kre
>
>