lex would suicide under some strange circumstances (not my lex code)
Turned out to be multiple Bterm()s of stdin.

-Steve

Reference: /n/sources/patch/applied/lex
Date: Mon Oct 18 19:38:41 CES 2004

--- /sys/src/cmd/lex/sub1.c	Mon Oct 18 19:38:43 2004
+++ /sys/src/cmd/lex/sub1.c	Mon Oct 18 19:38:41 2004
@@ -287,6 +287,7 @@
 	if(c == Beof) {
 		eof = TRUE;
 		Bterm(fin);
+		fin = 0;
 		return(0);
 	}
 	if(c == '\n')yyline++;
--- /sys/src/cmd/lex/lmain.c	Mon Oct 18 19:38:41 2004
+++ /sys/src/cmd/lex/lmain.c	Mon Oct 18 19:38:40 2004
@@ -38,7 +38,7 @@
 int funcflag;
 int pflag;
 int chset;	/* 1 = char set modified */
-Biobuf *fin, *fother;
+Biobuf *fin = 0, *fother;
 int fptr;
 int *name;
 int *left;
@@ -186,7 +186,8 @@
 		debug   ||
 # endif
 			report == 1)statistics();
-	Bterm(fin);
+	if (fin)
+		Bterm(fin);
 	exits(0);	/* success return code */
 }