(Limitations of Builtins): Describe "set -" problems.

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 89f8f6581f560663081a8a525036b93dfab14bda..d0f531415ae387bb3b966ce36977eb59bb271f2e 100644 (file)
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -11180,9 +11180,14 @@ processing as soon as a non-option argument is found.  Therefore, use
 set x $my_list; shift
 @end example
 
-Some shells have the "opposite" problem of not recognizing all options
+Avoid @samp{set -}, e.g., @samp{set - $my_list}.  POSIX 1003.1-2001 no
+longer requires support for this command, and in traditional shells
+@samp{set - $my_list} resets the @samp{-v} and @samp{-x} options, which
+makes scripts harder to debug.
+
+Some nonstandard shells do not recognize more than one option
 (e.g., @samp{set -e -x} assigns @samp{-x} to the command line).  It is
-better to elide these:
+better to combine them:
 
 @example
 set -ex