adds <>file and <>[fd]file to rc.  it's a natural fit for /net
and i've wanted it repeatedly.  i've been running this shell
for several days and nothing has broken.  brucee has these
changes and has been looking at them too.

Reference: /n/sources/patch/applied/rc-rdwr
Date: Fri Nov 19 20:55:09 CET 2004

--- /sys/src/cmd/rc/lex.c	Fri Nov 19 20:55:08 2004
+++ /sys/src/cmd/rc/lex.c	Fri Nov 19 20:55:08 2004
@@ -267,8 +267,10 @@
 			if(nextis(c)){
 				t->rtype = HERE;
 				*w++=c;
-			}
-			else t->rtype = READ;
+			} else if (nextis('>')){
+				t->rtype = RDWR;
+				*w++=c;
+			} else t->rtype = READ;
 			t->fd0 = 0;
 			break;
 		}
--- /sys/src/cmd/rc/rc.h	Fri Nov 19 20:55:09 2004
+++ /sys/src/cmd/rc/rc.h	Fri Nov 19 20:55:09 2004
@@ -74,6 +74,7 @@
 #define	HERE	4
 #define	DUPFD	5
 #define	CLOSE	6
+#define RDWR	7
 struct var{
 	char *name;		/* ascii name */
 	word *val;	/* value */
--- /sys/src/cmd/rc/code.c	Fri Nov 19 20:55:08 2004
+++ /sys/src/cmd/rc/code.c	Fri Nov 19 20:55:08 2004
@@ -319,6 +319,9 @@
 		case HERE:
 			emitf(Xread);
 			break;
+		case RDWR:
+			emitf(Xrdwr);
+			break;
 		}
 		emiti(t->fd0);
 		outcode(c1, eflag);
@@ -466,6 +469,7 @@
 		return;
 	for(p = cp+1;p->f;p++){
 		if(p->f==Xappend || p->f==Xclose || p->f==Xread || p->f==Xwrite
+		|| p->f==Xrdwr
 		|| p->f==Xasync || p->f==Xbackq || p->f==Xcase || p->f==Xfalse
 		|| p->f==Xfor || p->f==Xjump
 		|| p->f==Xsubshell || p->f==Xtrue) p++;
--- /sys/src/cmd/rc/pcmd.c	Fri Nov 19 20:55:08 2004
+++ /sys/src/cmd/rc/pcmd.c	Fri Nov 19 20:55:08 2004
@@ -110,7 +110,10 @@
 		case HERE:
 			pchr(f, '<');
 		case READ:
+		case RDWR:
 			pchr(f, '<');
+			if(t->rtype==RDWR)
+				pchr(f, '>');
 			if(t->fd0!=0)
 				pfmt(f, "[%d]", t->fd0);
 			break;
--- /sys/src/cmd/rc/exec.h	Fri Nov 19 20:55:08 2004
+++ /sys/src/cmd/rc/exec.h	Fri Nov 19 20:55:08 2004
@@ -5,6 +5,7 @@
 extern void Xconc(void), Xcount(void), Xdelfn(void), Xdol(void), Xqdol(void), Xdup(void);
 extern void Xexit(void), Xfalse(void), Xfn(void), Xfor(void), Xglob(void);
 extern void Xjump(void), Xmark(void), Xmatch(void), Xpipe(void), Xread(void);
+extern void Xrdwr(void);
 extern void Xrdfn(void), Xunredir(void), Xstar(void), Xreturn(void), Xsubshell(void);
 extern void Xtrue(void), Xword(void), Xwrite(void), Xpipefd(void), Xcase(void);
 extern void Xlocal(void), Xunlocal(void), Xassign(void), Xsimple(void), Xpopm(void);
--- /sys/src/cmd/rc/pfnc.c	Fri Nov 19 20:55:09 2004
+++ /sys/src/cmd/rc/pfnc.c	Fri Nov 19 20:55:08 2004
@@ -18,6 +18,7 @@
 	Xjump, "Xjump",
 	Xmark, "Xmark",
 	Xpopm, "Xpopm",
+	Xrdwr, "Xrdwr",
 	Xread, "Xread",
 	Xreturn, "Xreturn",
 	Xtrue, "Xtrue",
--- /sys/src/cmd/rc/exec.c	Fri Nov 19 20:55:08 2004
+++ /sys/src/cmd/rc/exec.c	Fri Nov 19 20:55:08 2004
@@ -219,6 +219,7 @@
  * Xpipefd[type]{... Xreturn}		connect {} to pipe (input or output,
  * 					depending on type), push /dev/fd/??
  * Xpopm(value)				pop value from stack
+ * Xrdwr(file)[fd]			open file for reading and writing
  * Xread(file)[fd]			open file to read
  * Xsettraps(names){... Xreturn}		define trap functions
  * Xshowtraps				print trap list
@@ -365,6 +366,33 @@
 	}
 	file = runq->argv->words->word;
 	if((f = open(file, 0))<0){
+		pfmt(err, "%s: ", file);
+		Xerror("can't open");
+		return;
+	}
+	pushredir(ROPEN, f, runq->code[runq->pc].i);
+	runq->pc++;
+	poplist();
+}
+
+void
+Xrdwr(void)
+{
+	char *file;
+	int f;
+
+	switch(count(runq->argv->words)){
+	default:
+		Xerror1("<> requires singleton\n");
+		return;
+	case 0:
+		Xerror1("<> requires file\n");
+		return;
+	case 1:
+		break;
+	}
+	file = runq->argv->words->word;
+	if((f = open(file, ORDWR))<0){
 		pfmt(err, "%s: ", file);
 		Xerror("can't open");
 		return;