Messages in this thread | | | Date | Tue, 1 Sep 1998 13:46:18 +0200 (MEST) | From | Clifford Wolf <> | Subject | Re: linux/Makefile: CONFIG_SHELL and SHELL |
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On 1 Sep 1998, Andreas Schwab wrote:
> Clifford Wolf <clifford@clifford.at> writes: > > |> On 31 Aug 1998, Andreas Schwab wrote: > |> > |> > Clifford Wolf <clifford@clifford.at> writes: > |> > > |> > |> At the top of the Makefile we set the variable CONFIG_SHELL which than > |> > |> should be a bash (if possible). Why don't setting the variable SHELL to > |> > |> the value of CONFIG_SHELL? If we need bash features we should force to > |> > |> use bash - or don't use bash features. > |> > > |> > Please do the latter. Setting SHELL to a nonstandard value (different > |> > from /bin/sh) causes *all* commands to be started with '$(SHELL) -c cmd' > |> > instead of internally by make (which knows about the /bin/sh parsing > |> > rules). That would kill performance quite a bit. > |> > |> I don't know much about the internals of GNU make - and I'm sure you are > |> right in theory - but this are the values I got: > |> > |> with "SHELL := $(CONFIG_SHELL)": > |> > |> real 13m32.125s > |> user 12m20.000s > |> sys 0m46.000s > |> > |> without "SHELL := $(CONFIG_SHELL)": > |> > |> real 13m14.745s > |> user 12m18.910s > |> sys 0m45.030s > > It depends on whether /bin/sh can be kept cached while the compiler is > running. If it needs to be loaded from disk each time then the difference > is noticable.
I've just had a look at the GNU make info page (File: make.info, Node: Execution) and they say at this page that make executes all commands useing a subshell and that it uses /bin/sh as subshell if the $(SHELL) variable is not set.
So it invokes a subshell anyway (regardless if $(SHELL) is set or not). The only difference is _which_ shell is used. And we defently would like to use bash (becouse we use bash features in our makefiles).
- clifford
-- -- -- -- -- -- -- -- -- -- -- -- -- Clifford Wolf magnet - Internet at Work IRC: efnet / clifford Director of System Development http://www.clifford.at/ e-mail: c.wolf@magnet.at email: god@clifford.at
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