NAME

       boottime, time_second, time_uptime — system time variables

SYNOPSIS

       #include <sys/time.h>

       extern struct timeval boottime;
       extern time_t time_second;
       extern time_t time_uptime;

DESCRIPTION

       The boottime variable holds the system boot time.

       The time_second variable is the system's “wall time” clock to the second.

       The time_uptime variable is the number of seconds since boot.

       The  bintime(9),  getbintime(9), microtime(9), getmicrotime(9), nanotime(9), and getnanotime(9) functions
       can be used to  get  the  current  time  more  accurately  and  in  an  atomic  manner.   Similarly,  the
       binuptime(9),  getbinuptime(9),  microuptime(9),  getmicrouptime(9),  nanouptime(9), and getnanouptime(9)
       functions can be used to get the time elapse since boot more accurately and in  an  atomic  manner.   The
       boottime variable may be read and written without special precautions.

SEE ALSO

       clock_settime(2),    ntp_adjtime(2),    settimeofday(2),    bintime(9),    binuptime(9),   getbintime(9),
       getbinuptime(9),  getmicrotime(9),  getmicrouptime(9),  getnanotime(9),  getnanouptime(9),  microtime(9),
       microuptime(9), nanotime(9), nanouptime(9)

       Poul-Henning  Kamp,  “Timecounters:  Efficient  and  precise  timekeeping in SMP kernels”, Proceedings of
       EuroBSDCon 2002, Amsterdam, /usr/share/doc/papers/timecounter.ascii.gz.

       Marshall Kirk McKusick and George V. Neville-Neil, The Design and Implementation of the FreeBSD Operating
       System, Addison-Wesley, 57-61,65-66, July 2004.

Debian                                         September 17, 2004                                        TIME(9)