Re: _AS_DETECT_BETTER_SHELL speedup

[Noah Misch]

On Sat, Jan 29, 2005 at 02:07:53PM +0100, Alexandre Duret-Lutz wrote:
> However my understanding is that modern shells already detect
> these cases and perform the optimization by themselves.  I know
> for sure that Zsh has the machinery for this (along with some
> other hairy tricks to limit forks at other places), and, from
> what I can observe from the command line, so does Bash.  

FWIW:

$ echo $BASH_VERSION
2.05b.0(1)-release
$ strace bash -c '(foo) 2>/dev/null' 2>&1 | grep clone
clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, 
child_tidptr=0x4000fe28) = 25378
$ strace bash -c '(exec foo) 2>/dev/null' 2>&1 | grep clone
clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, 
child_tidptr=0x4000fe28) = 25382
$ strace bash -c '{ exec foo; } 2>/dev/null' 2>&1 | grep clone
$ 

> IMHO: don't bother and let the shell do its job.

(No strong opinion here.)