Keeping track of many concurrent acme invocations in rio can be annoying.
While you can B2 'Local echo -n some_label > /dev/label' in a running acme,
there's no way to set the label on an acme window when starting it from the
command line or a script.

This patch adds a -L option that takes as its argument a label name for
the running acme. The label is valid only for the duration of the acme run,
preserving the parent rio window's label when acme terminates.

Reference: /n/sources/patch/maybe/acme-label
Date: Tue Oct 27 22:14:10 CET 2009
Signed-off-by: lyndon@orthanc.ca

--- /sys/src/cmd/acme/acme.c	Tue Oct 27 22:06:57 2009
+++ /sys/src/cmd/acme/acme.c	Tue Oct 27 22:06:54 2009
@@ -57,10 +57,10 @@
 threadmain(int argc, char *argv[])
 {
 	int i;
-	char *p, *loadfile;
+	char *p, *label, *loadfile;
 	char buf[256];
 	Column *c;
-	int ncol;
+	int labelfd, ncol;
 	Display *d;
 	static void *arg[1];
 
@@ -68,6 +68,7 @@
 
 	ncol = -1;
 
+	label = nil;
 	loadfile = nil;
 	ARGBEGIN{
 	case 'a':
@@ -99,9 +100,14 @@
 		if(loadfile == nil)
 			goto Usage;
 		break;
+	case 'L':
+		label = ARGF();
+		if(label == nil)
+			goto Usage;
+		break;
 	default:
 	Usage:
-		fprint(2, "usage: acme [-ab] [-c ncol] [-f font] [-F fixedfont] [-l loadfile | file...]\n");
+		fprint(2, "usage: acme [-ab] [-c ncol] [-f font] [-F fixedfont] [-L label] [-l loadfile | file...]\n");
 		exits("usage");
 	}ARGEND
 
@@ -184,6 +190,11 @@
 	plumbsendfd = plumbopen("send", OWRITE|OCEXEC);
 
 	fsysinit();
+	if(label){
+		labelfd = open("/dev/label", ORDWR);
+		write(labelfd, label, strlen(label));
+		close(labelfd);
+	}
 
 	#define	WPERCOL	8
 	disk = diskinit();
--- /sys/man/1/acme	Tue Oct 27 22:07:03 2009
+++ /sys/man/1/acme	Tue Oct 27 22:06:59 2009
@@ -19,6 +19,10 @@
 .I fixfont
 ]
 [
+.B -L
+.I label
+]
+[
 .B -l
 .I loadfile
 |
@@ -76,6 +80,11 @@
 Tab intervals are set to the width of 4 (or the value of
 .BR $tabstop )
 numeral zeros in the appropriate font.
+.PP
+The
+.B -L
+option sets the label of the acme window for the duration of
+its run.
 .PP
 .SS Windows
 .I Acme