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times(2) - times, times - get process times - man 2 times

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TIMES(2)                   Linux Programmer's Manual                  TIMES(2)



NAME
       times - get process times

SYNOPSIS
       #include <sys/times.h>

       clock_t times(struct tms *buf);

DESCRIPTION
       The times() function stores the current process times in(1,8) the struct tms
       that buf points to.  The struct tms is as defined in(1,8) <sys/times.h>:

       struct tms {
              clock_t tms_utime;  /* user time(1,2,n) */
              clock_t tms_stime;  /* system time(1,2,n) */
              clock_t tms_cutime; /* user time(1,2,n) of children */
              clock_t tms_cstime; /* system time(1,2,n) of children */
       };

       The tms_utime field contains the CPU time(1,2,n) spent executing  instructions
       of  the  calling  process.   The  tms_stime field contains the CPU time(1,2,n)
       spent in(1,8) the system while executing tasks  on  behalf  of  the  calling
       process.   The  tms_cutime  field contains the sum of the tms_utime and
       tms_cutime  values  for  all  waited-for  terminated   children.    The
       tms_cstime  field contains the sum of the tms_stime and tms_cstime val-
       ues for all waited-for terminated children.

       Times for terminated children (and their descendants) is  added  in(1,8)  at
       the  moment wait(2) or waitpid(2) returns their process ID. In particu-
       lar, times of grandchildren that the children  did  not  wait  for  are
       never seen.

       All times reported are in(1,8) clock(3,n) ticks.

RETURN VALUE
       The  function times returns the number of clock(3,n) ticks that have elapsed
       since an arbitrary point in(1,8) the past.  For  Linux  this  point  is  the
       moment  the system was booted.  This return value may overflow the pos-
       sible range of type clock_t.  On error(8,n), (clock_t) -1 is  returned,  and
       errno is set(7,n,1 builtins) appropriately.

NOTES
       The number of clock(3,n) ticks per second can be obtained using
              sysconf(_SC_CLK_TCK);
       In  POSIX-1996 the symbol CLK_TCK (defined in(1,8) <time.h>) is mentioned as
       obsolescent. It is obsolete now.

       On Linux, if(3,n) the disposition of SIGCHLD is  set(7,n,1 builtins)  to  SIG_IGN  then  the
       times   of  terminated  children  are  automatically  included  in(1,8)  the
       tms_cstime and tms_cutime fields, although POSIX 1003.1-2001 says  that
       this should only happen if(3,n) the calling process wait()s on its children.

       Note that clock(3,n)(3) returns values of type clock_t that are not measured
       in(1,8) clock(3,n) ticks but in(1,8) CLOCKS_PER_SEC.

CONFORMING TO
       SVr4, SVID, POSIX, X/OPEN, BSD 4.3

HISTORICAL NOTES
       SVr1-3  returns long and the struct members are of type time_t although
       they store clock(3,n) ticks, not seconds since the epoch.  V7 used long  for
       the struct members, because it had no type time_t yet.

       On  older  systems the number of clock(3,n) ticks per second is given by the
       variable HZ.

SEE ALSO
       time(1,2,n)(1), getrusage(2), wait(2), clock(3,n)(3), sysconf(3)



Linux                             2002-06-14                          TIMES(2)

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