How to find out the time in seconds since log on?
See the utmpx(5) interface, specifically endutxent(3). It's the programmatic interface to what you're looking at from who and last.
At the end I used getlastlogx(), thanks for Rob Napier for pointing me to the right direction (+1).
this is I came up with:
struct lastlogx *lastLogin; uid_t myuid = getuid(); lastLogin = getlastlogx(myuid,nil); NSDate *dateAtLogon = [NSDate dateWithTimeIntervalSince1970:lastLogin->ll_tv.tv_sec]; NSDate *currentDate = [NSDate date]; NSTimeInterval timeSinceLogin = [currentDate timeIntervalSinceDate:dateAtLogon]; NSLog(@"%1.1f seconds since logon",timeSinceLogin);