From "Philippe Charnier" <charnier@lirmm.fr>:

There is a bug in sh: the built in command "fc -l" generates
a core dump (*NULL in not_fcnumber).

According to the sh manual page (fc  -l [-nr] [first [last]]), fc -l
is a correct sequence (in that case, values are defaulted to -16 and -1)
but fails when first is not given.

bin/sh/histedit.c

@@ -33,7 +33,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id$
+ *	$Id: histedit.c,v 1.2 1994/09/24 02:57:36 davidg Exp $
  */
 
 #ifndef lint
@@ -389,6 +389,10 @@ fc_replace(s, p, r)
 not_fcnumber(s)
         char *s;
 {
+	if (s == NULL) {
+		/* NULL is not a fc_number */
+		return (1);
+	}
         if (*s == '-')
                 s++;
 	return (!is_number(s));