Subject: Re: make -j and failure modes
To: David Laight <>
From: Greywolf <>
List: tech-userlevel
Date: 12/10/2003 14:01:31
Thus spake David Laight ("DL> ") sometime Today...

DL> > I have two thoughts on this:
DL> > 1.  Make understands this already.
DL> > 2.  Are you (David) saying "change make to understand
DL> > target:	source
DL> > 	cd xxx
DL> > 	yyy
DL> > ??  i.e. "cd" actually takes effect over more than one line?
DL> Make currently looks at command lines and if they contain any special
DL> characters (even if quoted!) fires the command into the shell.
DL> Command that don't contain special characters are tokenised by make
DL> and it does a fork/exec itself.

Hm.  That's interesting; didn't know it did that...

DL> If a command is recognised as 'cd xxx; yyy' make could fork, cd and exec.
DL> Other optimisations (eg builtin echo) might also be benefitial.

What if you have strings of those, i.e.

	cd xxx; yyy; cd xxn; yyz; cd foo; bar; ...

You only gain one level of optimization, unless you're thinking make
should also be parsing command lines (which is starting to sound like a

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