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NAME

       times - get process times

SYNOPSIS

       #include <sys/times.h>

       clock_t times(struct tms *buf);

DESCRIPTION

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

       struct tms {
              clock_t tms_utime;  /* user time */
              clock_t tms_stime;  /* system time */
              clock_t tms_cutime; /* user time of dead children */
              clock_t tms_cstime; /* system time of dead children */
       };

       The tms_utime field contains the CPU time spent executing  instructions
       of  the  calling  process.   The  tms_stime field contains the CPU time
       spent in 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
       values for all waited-for terminated children.

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

       All times reported are in clock ticks.

RETURN VALUE

       times()  returns  the  number of clock ticks that have elapsed since an
       arbitrary point in the past.  For Linux 2.4 and earlier this  point  is
       the  moment  the  system  was  booted.   Since Linux 2.6, this point is
       (2^32/HZ) - 300 (i.e., about 429 million) seconds  before  system  boot
       time.   The  return  value  may  overflow  the  possible  range of type
       clock_t.  On  error,  (clock_t)  -1  is  returned,  and  errno  is  set
       appropriately.

NOTES

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 It is obsolete now.

       In Linux kernel versions before 2.6.9, if the disposition of SIGCHLD is
       set  to SIG_IGN then the times of terminated children are automatically
       included in  the  tms_cstime  and  tms_cutime  fields,  although  POSIX
       1003.1-2001  says  that  this should only happen if the calling process
       wait()s on its children.  This non-conformance is  rectified  in  Linux
       2.6.9 and later.

       On  Linux,  the  buf argument can be specified as NULL, with the result
       that times() just returns a function result.  However, POSIX  does  not
       specify  this  behaviour, and most other Unix implementations require a
       non-NULL value for buf.

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

CONFORMING TO

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

HISTORICAL NOTES

       SVr1-3  returns long and the struct members are of type time_t although
       they store clock 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 ticks per second is given by the
       variable HZ.

SEE ALSO

       time(1), getrusage(2), wait(2), clock(3), sysconf(3)