msleep -- millisecond sleep.  i wrote this for hitting a particular value of /dev/^(date rtc)
without worring about missing the desired second or doing math with an external program.
e.g.

	end = futuretime
	while(! ~ `{/cat /dev/rtc} $end)
		msleep 500


Notes:
Tue Sep 12 07:45:09 EDT 2006 rsc
    Sorry, but no.  Next you'll want us to introduce lseek.
    


Reference: /n/sources/patch/sorry/msleep
Date: Sun Aug 13 17:40:18 CES 2006
Signed-off-by: quanstro@quanstro.net
Reviewed-by: rsc

--- /sys/man/1/sleep	Sun Aug 13 17:31:13 2006
+++ /sys/man/1/sleep	Sun Aug 13 17:31:10 2006
@@ -4,11 +4,16 @@
 .SH SYNOPSIS
 .B sleep
 .I time
+.br
+.B msleep
+.I time
 .SH DESCRIPTION
 .I Sleep
 suspends execution for
 .I time
-seconds.
+seconds; msleep suspends execution for
+.I time
+milliseconds.
 .SH EXAMPLES
 Execute a command
 100 seconds hence.
--- /sys/man/1/INDEX	Sun Aug 13 17:31:33 2006
+++ /sys/man/1/INDEX	Sun Aug 13 17:31:28 2006
@@ -234,6 +234,7 @@
 seq seq
 size size
 sleep sleep
+msleep sleep
 sort sort
 spell spell
 sprog spell
--- /sys/src/cmd/msleep.c	Thu Jan  1 00:00:00 1970
+++ /sys/src/cmd/msleep.c	Sun Aug 13 17:31:51 2006
@@ -0,0 +1,16 @@
+#include <u.h>
+#include <libc.h>
+
+void
+main(int argc, char **argv)
+{
+	vlong ms;
+
+	if(argc>1)
+		for(ms = atoll(argv[1]); ms > 0; ms -= 1000)
+			if(ms >= 1000)
+				sleep(1000);
+			else
+				sleep(ms);
+	exits(0);
+}