I very much like this patch.  I realized right away that I would never
again need to restart dwm when I work on my status script.  When it
dies, I can just start it up again without restarting DWM.  Someone
could even have multiple programs running to update the status text.  It
removes the need for the "readin" variable: you either set the property
or you don't.

The patch removes 39 SLOC:

    1546    dwm-5.3.1       ansic=1546
    1585    dwm-5.3.1-orig  ansic=1585

This would be 40 if the property were hard coded to XA_WM_NAME.  I left
in a comment to use a property named "DWM_STATUS" instead of XA_WM_NAME,
so people could play with it easily, but I think XA_WM_NAME is
ultimately the right way to do it.

To use this, modify your status script to use "xsetroot -name" instead
of "echo".  For instance:

    while true; do
        xsetroot -name "$(date)"
        sleep 1
    done

You could also pipe an existing status script to an xsetroot loop like
so:

    status | while read line; do xsetroot -name "$line"; done

If you'd prefer to not use the otherwise-unused WM_NAME property of the
root window, uncomment the commented "statusatom" line, and use xprop as
I detailed in my previous email to the list.  I decided WM_NAME was a
good choice, since the default is to display "dwm-"VERSION, and since
xsetroot has a nicer syntax than xprop.

Neale

-----8<----- cut here -----8<-----
diff -ur dwm-5.3.1.orig/config.def.h dwm-5.3.1/config.def.h
--- dwm-5.3.1.orig/config.def.h 2008-12-06 02:33:03.000000000 -0700
+++ dwm-5.3.1/config.def.h      2008-12-08 22:39:49.000000000 -0700
@@ -12,7 +12,6 @@
 static unsigned int snap            = 32;       /* snap pixel */
 static Bool showbar                 = True;     /* False means no bar */
 static Bool topbar                  = True;     /* False means bottom bar */
-static Bool readin                  = True;     /* False means do not read 
stdin */
 static Bool usegrab                 = False;    /* True means grabbing the X 
server
                                                    during mouse-based resizals 
*/
 
diff -ur dwm-5.3.1.orig/dwm.c dwm-5.3.1/dwm.c
--- dwm-5.3.1.orig/dwm.c        2008-12-06 02:33:03.000000000 -0700
+++ dwm-5.3.1/dwm.c     2008-12-08 22:39:49.000000000 -0700
@@ -6,12 +6,9 @@
  * events about window (dis-)appearance.  Only one X connection at a time is
  * allowed to select for this event mask.
  *
- * Calls to fetch an X event from the event queue are blocking.  Due reading
- * status text from standard input, a select()-driven main loop has been
- * implemented which selects for reads on the X connection and STDIN_FILENO to
- * handle all data smoothly. The event handlers of dwm are organized in an
- * array which is accessed whenever a new event has been fetched. This allows
- * event dispatching in O(1) time.
+ * The event handlers of dwm are organized in an array which is accessed
+ * whenever a new event has been fetched. This allows event dispatching
+ * in O(1) time.
  *
  * Each child of the root window is called a client, except windows which have
  * set the override_redirect flag.  Clients are organized in a global
@@ -30,7 +27,6 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
-#include <sys/select.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <X11/cursorfont.h>
@@ -196,6 +192,7 @@
 static void updategeom(void);
 static void updatenumlockmask(void);
 static void updatesizehints(Client *c);
+static void updatestatus(void);
 static void updatetitle(Client *c);
 static void updatewmhints(Client *c);
 static void view(const Arg *arg);
@@ -227,7 +224,7 @@
        [PropertyNotify] = propertynotify,
        [UnmapNotify] = unmapnotify
 };
-static Atom wmatom[WMLast], netatom[NetLast];
+static Atom wmatom[WMLast], netatom[NetLast], statusatom;
 static Bool otherwm;
 static Bool running = True;
 static Client *clients = NULL;
@@ -998,9 +995,11 @@
        Window trans;
        XPropertyEvent *ev = &e->xproperty;
 
-       if(ev->state == PropertyDelete)
+       if((ev->window == root) && (ev->atom = statusatom))
+               updatestatus();
+       else if(ev->state == PropertyDelete)
                return; /* ignore */
-       if((c = getclient(ev->window))) {
+       else if((c = getclient(ev->window))) {
                switch (ev->atom) {
                default: break;
                case XA_WM_TRANSIENT_FOR:
@@ -1026,7 +1025,7 @@
 
 void
 quit(const Arg *arg) {
-       readin = running = False;
+       running = False;
 }
 
 void
@@ -1180,60 +1179,13 @@
 
 void
 run(void) {
-       char *p;
-       char sbuf[sizeof stext];
-       fd_set rd;
-       int r, xfd;
-       unsigned int len, offset;
        XEvent ev;
 
-       /* main event loop, also reads status text from stdin */
+       /* main event loop */
        XSync(dpy, False);
-       xfd = ConnectionNumber(dpy);
-       offset = 0;
-       len = sizeof stext - 1;
-       sbuf[len] = stext[len] = '\0'; /* 0-terminator is never touched */
-       while(running) {
-               FD_ZERO(&rd);
-               if(readin)
-                       FD_SET(STDIN_FILENO, &rd);
-               FD_SET(xfd, &rd);
-               if(select(xfd + 1, &rd, NULL, NULL, NULL) == -1) {
-                       if(errno == EINTR)
-                               continue;
-                       die("select failed\n");
-               }
-               if(FD_ISSET(STDIN_FILENO, &rd)) {
-                       switch((r = read(STDIN_FILENO, sbuf + offset, len - 
offset))) {
-                       case -1:
-                               strncpy(stext, strerror(errno), len);
-                               readin = False;
-                               break;
-                       case 0:
-                               strncpy(stext, "EOF", 4);
-                               readin = False;
-                               break;
-                       default:
-                               for(p = sbuf + offset; r > 0; p++, r--, 
offset++)
-                                       if(*p == '\n' || *p == '\0') {
-                                               *p = '\0';
-                                               strncpy(stext, sbuf, len);
-                                               p += r - 1; /* p is sbuf + 
offset + r - 1 */
-                                               for(r = 0; *(p - r) && *(p - r) 
!= '\n'; r++);
-                                               offset = r;
-                                               if(r)
-                                                       memmove(sbuf, p - r + 
1, r);
-                                               break;
-                                       }
-                               break;
-                       }
-                       drawbar();
-               }
-               while(XPending(dpy)) {
-                       XNextEvent(dpy, &ev);
-                       if(handler[ev.type])
-                               (handler[ev.type])(&ev); /* call handler */
-               }
+       while(running && !XNextEvent(dpy, &ev)) {
+               if(handler[ev.type])
+                       (handler[ev.type])(&ev); /* call handler */
        }
 }
 
@@ -1322,6 +1274,8 @@
        wmatom[WMState] = XInternAtom(dpy, "WM_STATE", False);
        netatom[NetSupported] = XInternAtom(dpy, "_NET_SUPPORTED", False);
        netatom[NetWMName] = XInternAtom(dpy, "_NET_WM_NAME", False);
+       /* statusatom = XInternAtom(dpy, "DWM_STATUS", False); */
+       statusatom = XA_WM_NAME;
 
        /* init cursors */
        wa.cursor = cursor[CurNormal] = XCreateFontCursor(dpy, XC_left_ptr);
@@ -1356,8 +1310,7 @@
                        CWOverrideRedirect|CWBackPixmap|CWEventMask, &wa);
        XDefineCursor(dpy, barwin, cursor[CurNormal]);
        XMapRaised(dpy, barwin);
-       strcpy(stext, "dwm-"VERSION);
-       drawbar();
+       updatestatus();
 
        /* EWMH support per view */
        XChangeProperty(dpy, root, netatom[NetSupported], XA_ATOM, 32,
@@ -1365,7 +1318,8 @@
 
        /* select for events */
        wa.event_mask = 
SubstructureRedirectMask|SubstructureNotifyMask|ButtonPressMask
-                       |EnterWindowMask|LeaveWindowMask|StructureNotifyMask;
+                       |EnterWindowMask|LeaveWindowMask|StructureNotifyMask
+                       |PropertyChangeMask;
        XChangeWindowAttributes(dpy, root, CWEventMask|CWCursor, &wa);
        XSelectInput(dpy, root, wa.event_mask);
 
@@ -1647,6 +1601,13 @@
 }
 
 void
+updatestatus() {
+       if(!gettextprop(root, statusatom, stext, sizeof(stext)))
+               strcpy(stext, "dwm-"VERSION);
+       drawbar();
+}
+
+void
 updatewmhints(Client *c) {
        XWMHints *wmh;
 
-----8<----- cut here -----8<-----

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