Question

I like to know how much time in second has elapsed since the user logged on. (TickCount is not good because that is from system start)

I know I can use last or who to get the timestamp but what I am looking for a simple but robust solution.
I would use it in Cocoa but a unix command is fine.

Answer 1

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);