function obtains the ID of the CPU-time clock of the process whose ID is
and returns it in the location pointed to by
is zero, then the clock ID of the CPU-time clock
of the calling process is returned.
on error, it returns one of the positive error numbers listed in ERRORS.
The kernel does not support obtaining the per-process
CPU-time clock of another process, and
does not specify the calling process.
The caller does not have permission to access
the CPU-time clock of the process specified by
(Specified as an optional error in POSIX.1-2001;
does not occur on Linux unless the kernel does not support
obtaining the per-process CPU-time clock of another process.)
There is no process with the ID
function is available in glibc since version 2.2.
with the clock ID obtained by a call to
is the same as using the clock ID
The example program below obtains the
CPU-time clock ID of the process whose ID is given on the command line,
and then uses
to obtain the time on that clock.
An example run is the following:
$ ./a.out 1 # Show CPU clock of init process
CPU-time clock for PID 1 is 2.213466748 seconds