ref: 36eb768c5a6858183ea246f2f363a57cbcf3cb9d
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
}