exec("uptime",$output);

//11:04:42 up 25 days, 21:23,  6 users,  load average: 0.08, 0.08, 0.04

$uptime = ereg("^([[:digit:]]{1,2}:([[:digit:]]{2})(AM|PM)?) up (.+) day, ([[:digit:]]{1,2}:([[:digit:]]{2})?), 
(.{2}) user(s)?,  load averages: (.+)$", trim($output[0]),$regs);

echo $uptime;