Need help with understanding output of ps -ef on linux

Question

When I do ps -ef on my Linux box, I get: UID PID PPID C STIME TTY TIME CMD

Please help me with meaning of C,TIME. is the TIME , the actual cpu time allocated to the process?

Answer 1

If you run man ps then type /SpaceShift+CSpaceEnter, you should see this line.

   C     pcpu         cpu utilization

but that's under the OBSOLETE SORT KEYS header, so is not what we're looking for.

Press n to find the next match:

   c           C         processor utilization. Currently, this is the
                         integer value of the percent usage over the
                         lifetime of the process.
                         (see %cpu).

which sounds right. For more details, we search for %cpu and find:

   %cpu        %CPU      cpu utilization of the process in "##.#" format.
                         Currently, it is the CPU time used divided by the
                         time the process has been running cputime/realtime
                         ratio), expressed as a percentage. ...
                         (alias pcpu).

And TIME has two matches, but only one that matches the hh:mm:ss format:

   cputime     TIME      cumulative CPU time, "[DD-]hh:mm:ss" format. (alias time).

---

Cumulative CPU time is the amount of time the processor spent running the process, i.e. actually using CPU cycles, not sleeping, waiting to run, or waiting for I/O.

It's determined by summing the utime and stime values that are described in the proc(5) man page.

  utime %lu   Amount of time that this process has been scheduled in user mode...
  stime %lu   Amount of time that this process has been scheduled in kernel mode...