docs: update entry about unset.

* doc/autoconf.texi (Limitations of Builtins): NetBSD sh unset
also fails upon `unset' of a variable that is not set.  Bash 2.01
could also dump core over `unset MAILPATH'.
Suggestion by Eric Blake.

Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>

diff --git a/ChangeLog b/ChangeLog
index 13594f183adbac13234601c8bd4a7ed6b9d22098..8b7052aa73eb3743856b3d5577bac7190de5d248 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2011-01-22  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
+
+       docs: update entry about unset.
+       * doc/autoconf.texi (Limitations of Builtins): NetBSD sh unset
+       also fails upon `unset' of a variable that is not set.  Bash 2.01
+       could also dump core over `unset MAILPATH'.
+       Suggestion by Eric Blake.
+
 2011-01-21  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
 
        Fix LEXLIB and YYTEXT_POINTER with IRIX 6.5 flex 2.5.4.

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 4cb3a8c6b441d4a7a0a09a45da43927558fb4c00..7eccba7e40325bb47c6190db6f8764f1e4b14856 100644 (file)
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -17758,13 +17758,15 @@ and file name expansion.
 @item @command{unset}
 @c ------------------
 @prindex @command{unset}
-In some nonconforming shells (e.g., Bash 2.05a), @code{unset FOO} fails
-when @code{FOO} is not set.  You can use
+In some nonconforming shells (e.g., NetBSD 5.99.43 sh or Bash 2.05a),
+@code{unset FOO} fails when @code{FOO} is not set.  This can interfere
+with @code{set -e} operation.  You can use
 
 @smallexample
 FOO=; unset FOO
 @end smallexample
 
+@noindent
 if you are not sure that @code{FOO} is set.
 
 A few ancient shells lack @command{unset} entirely.  For some variables
@@ -17777,8 +17779,8 @@ PS1='$ '
 Usually, shells that do not support @command{unset} need less effort to
 make the environment sane, so for example is not a problem if you cannot
 unset @command{CDPATH} on those shells.  However, Bash 2.01 mishandles
-@code{unset MAIL} in some cases and dumps core.  So, you should do
-something like
+@code{unset MAIL} and @code{unset MAILPATH} in some cases and dumps core.
+So, you should do something like
 
 @smallexample
 ( (unset MAIL) || exit 1) >/dev/null 2>&1 && unset MAIL || :