Stepan Kasal <kasal@xxxxxx> writes:
> The item about `!' mentions the following code:
>
> if @var{command}; then (exit 1); else :; fi
>
> Can I change the suggestion to
>
> if @var{command}; then false; else :; fi
>
> Yes, the exit code might be 255, but it shouldn't matter.
The context is a general rewrite (the preceding text is "More
generally, one can always rewrite @samp{! @var{command}} as:") so we
should give a rewrite that works in the general case. Since "!"
always returns exit status 0 or 1, the rewrite should too. So we
can't use "false" in the rewrite.
I installed this hopefully-simpler patch for the "test !" problem:
2005-01-21 Paul Eggert <eggert@xxxxxxxxxxx>
* doc/autoconf.texi (Limitations of Builtins): Clarify that
"if test -d foo; ..." is portable. Suggested by Stepan Kasal.
--- autoconf.texi 21 Jan 2005 00:03:40 -0000 1.865
+++ autoconf.texi 21 Jan 2005 19:31:51 -0000 1.866
@@ -11082,8 +11082,9 @@ operators; consequently, Posix does not
is nonportable. If you combine @samp{&&} and @samp{||} in the same
statement, keep in mind that they have equal precedence.
-You may use @samp{!} with @command{test}, but not with @command{if}:
-@samp{test ! -r foo || exit 1}.
+It is safe to use @samp{!} as a @command{test} operator. For example,
+@samp{if test ! -d foo; @dots{}} is portable even though @samp{if ! test
+-d foo; @dots{}} is not.
@item @command{test} (files)
_______________________________________________
Autoconf mailing list
Autoconf@xxxxxxx
http://lists.gnu.org/mailman/listinfo/autoconf
