Modified xmonad-clock.c to display battery information from ACPI (will work only on linux though). Also restored three load averages instead of only one.

scripts/xmonad-acpi.c

@@ -0,0 +1,82 @@
+/*
+
+dwm/xmonad status bar provider. launch from your .xinitrc, and pipe
+into dzen2.
+ 
+to compile: gcc -Os -s -o xmonad-acpi xmonad-acpi.c
+ 
+Copyright (c) 2007, Tom Menari <tom dot menari at googlemail dot com>
+Copyright (c) 2007, Don Stewart
+ 
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+ 
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+ 
+#include <stdio.h>
+#include <time.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <signal.h>
+ 
+/* configuration */
+#define REFRESH_RATE    2
+#define TIME_FORMAT     "%a %b %d %H:%M:%S" 
+#define BATTERY_INFO    "/proc/acpi/battery/BAT0/info"
+#define BATTERY_STATE   "/proc/acpi/battery/BAT0/state"
+ 
+int main(void) {
+    FILE *acpi;
+    char b[34];
+    time_t epochtime;
+    struct tm *realtime;
+    int last_full, remaining;
+
+    double load[3];
+ 
+    signal(SIGPIPE, SIG_IGN);
+
+    if ((acpi = fopen(BATTERY_INFO, "r")) == NULL) {
+        perror("couldn't open "BATTERY_INFO);
+        exit(-1);
+    }
+    while (fgets(b, sizeof(b), acpi)) 
+        if (sscanf(b, "last full capacity: %d", &last_full) == 1)
+            break;
+    fclose(acpi);
+ 
+    for(;;) {
+        /* Load */
+        getloadavg(load, 3);
+
+        /* Battery */
+        if ((acpi = fopen(BATTERY_STATE, "r")) == NULL) {
+            perror("couldn't open "BATTERY_STATE);
+            exit(-1);
+        }
+        while (fgets(b, sizeof(b), acpi))
+            if (sscanf(b, "remaining capacity: %d", &remaining) == 1)
+                break;
+        fclose(acpi);
+        
+        /* Time */
+        epochtime = time(NULL);
+        realtime  = localtime(&epochtime);
+        strftime(b, sizeof(b), TIME_FORMAT, realtime);
+
+
+        fprintf(stdout, "%s | %.2f %.2f %.2f | %.1f%% \n", b, load[0], load[1], 
+                load[2], (float) (remaining * 100) / last_full);
+        fflush(stdout);
+        sleep(REFRESH_RATE);
+    }
+    return EXIT_SUCCESS;
+}