Hello Akim,
* Akim Demaille wrote on Tue, Jun 13, 2006 at 12:14:15PM CEST:
I would like to suggest embedding a probe in Autoconf's test suite to
check whether `!' (not as an argument to `test', but as a prefix for
any command) is portable or not. The documentation says it is not
portable, but I haven't seen a machine that doesn't support it. Yet
it is very handy in many situations.
$ cat foo.sh
if ! false; then echo yes; fi
$ /bin/sh foo.sh
foo.sh: !: not found
$ config.guess
alphaev67-dec-osf5.1
It also fails with Solaris /bin/sh, as documented in "Limitations of
Builtins".