ref: b66f5fc73ebf6d53cbbab66afc3676b5cc71fa9e
dir: /rc/bin/uptime/
#!/bin/awk -f
BEGIN{
	getline sysname < "/dev/sysname";
	getline < "/dev/time";
	sec = sprintf("%d", $3/$4);
	ct = sprintf("%02d:%02d:%02d", sec%86400/3600, sec%86400%3600/60, sec%60);
	printf("%s up %d days, %s\n", sysname, sec/86400, ct);
	exit
}