Re: _AS_DETECT_BETTER_SHELL speedup

[Noah Misch]

On Mon, Jan 31, 2005 at 08:30:08AM +0100, Stepan Kasal wrote:
> On Sat, Jan 29, 2005 at 06:34:19AM -0800, Noah Misch wrote:
> > It indeed turns out that `bash' and the V7 Bourne shell fork in all three 
> > cases,
> > `ash' and `pdksh' fork only in the first two, and `zsh' forks for none.

> But yes, this proves that "{ ...; }" has no advantage over "(exec ...)".

Systems where /bin/sh is ash (NetBSD, FreeBSD, Cygwin), or ksh (OpenBSD, some
modern Unix systems) and no other shell takes precedence still win.

Cygwin /bin/sh executes the former construct in 1/3 the time of the latter.

Most Cygwin systems have a /bin/bash.  `configure' will re-exec under that, so
as the best-shell heuristics stand this would indeed help Cygwin negligibly.