Re: A couple of config(1) questions

[Masao Uebayashi <uebayasi%gmail.com@localhost>]

On Sun, May 10, 2015 at 12:08 PM, Paul Goyette <paul%vps1.whooppee.com@localhost> wrote:
> The man page for config(9) says the syntax for including source files is
>
>         file pathname [attributes [flags]] [rule]
>
> It doesn't actually describe the syntax for [rule] but examples seem to
> indicate that we can do at least rudimentary boolean expressions, ie
>
>         x & y
>         x | y | z
>         x & !w
>
> Just how complex can these expressions be?  For example, can I use
>
>         (a | b) & (x | y | z)
>
> with parentheses?

That should be possible ... but I would strongly discourage those
expressions.  In the ideally modular world, one *.c file belongs to
one module.  That expression was necessary because in the old days
kernel was considered to be a single module (== monolithic).

> Question 2:  does config(1) support '\' at the end of a physical line to
> indicate line continuation?  (If the complex boolean expression above is
> supported, I'm likely to have a longer-than-80-char command!)

According to usr.bin/config/scan.l [1], you can simply continue a line
by putting a non-whitespace just after '\n'.  (If this is wrong, write
a test and add it to tests/usr.bin/config. :)

[1] http://nxr.netbsd.org/xref/src/usr.bin/config/scan.l#349