Re: [RFC PATCH] Add a 'minimal tree install' target

[Oleg Verych <olecom@flower.upol.cz>]

Hallo.

On Thu, Sep 13, 2007 at 09:19:38PM +0200, Sam Ravnborg wrote:
[]
> > 
> >     sed -n "s/^ALTARCH[[:space:]]:=[[:space:]]\(.*$\)\+/\1/p"
> > 
> > (i'm sure there is a better way though)
> 
> Oleg (added to mail) - you are quite confident in sed et al.
> Let us know if there is a simpler way.
> 
> (We want to pick i386 from include/asm-x86_64/Kbuild
> and similar for the architectures that uses ARCHDEF).

That particular one-line `ALTARCH := i386' of course can be matched
simpler, because there's only *one* (as written above) whitespace and no
make's assignment variations, like (?=,=). I wonder, if there can be more
options, than i386 and more occurrences of `ALTARCH' actually :) Also,
make can have lead whitespace on line start, as well as near assignment
sign, if that matters.

So, to match *one* line with *one* `ALTARCH' followed by `i386'

sed -n '/ALTARCH/{/i386/{p ; q}}' 

is fine by me. If there are dis-assignments, so to speak, or comments
with i386 this will not work obviously. But it's fast and must work
with variety of make syntax. Check is "for non empty output".

Also, please take a look on man isspace(). It matches much more
characters, than necessary for ordinary syntax whitespace. Using
[:blank:] (i.e. tab and space, with no options) is OK. Last thing: i'm not
sure, what that `+' is. I stick to BRE in sed, as it should be, so just
don't know what it does.

Hope that helps.
____