To do this we run e and f options at the same time

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To do this we run -e and f options at the same time. Again, -e will display all the processes running on the system and the f option displays extended information about each of those processes. Press Enter and now we see a lot more information displayed about each process. Let's scroll up here to the top so we can see what the names of the columns are. First we have the UID column. The UID column displays the name of the user account that owns that particular process. Usually that's the name of the user that initially launched the command togenerate that process. And as you can see most of these system processes here are owned by the root user, the super user on the system. We have the PID column like we did before, but we also have the PPID column too. The parent process ID. Anytime you have one process that launches another process, the process that launched the second process is called the parent process, the process that gets launched is called the child process. For example, let's look at this process right here, it's got a process ID number of six. But it says that its parent process ID is two. So if we go up in to PID column we can find this process right here. We know from this output that this process here launched this process right here. In fact it launched a whole bunch of these processes. Notice that a lot of these system processes all have the same parent process ID right here this process. The C column specifies how much processor time is being utilized by that process and we also have the S time column which specifies the time that the process was launched. So as you can see this system came up at 10:31 in the morning. That's when all these system processes were loaded. Now if you want to really crank up the amount of information displayed in the output of the ps command add an 'l' to the command. I like to remember it as ps -elf. The -l option displayed the long format of the ps output. If I press Enter even more information is displayed about each process running on the system. Let's scroll up to the top. For example we've added another column to the output labeled as S. This identifies the state of the process and this can be really useful. If there's a D in this column it means that the process has gone to sleep and it cannot be interrupted from sleep. An R in this column indicates that the process is just running normally. An S in this column which a lot of these system processes have indicates that the process is sleeping but can be interrupted if need be. If you see a T in this column it means that the process was stopped for some reason. Identify a Zombied Process 5:16-6:24 And if you see a Z in this column it indicates you can have a zombied process. A zombied process is one where basically a process got launched and exited out but things didn't get cleaned up after it exited and that's a little bit of a problem. We call it a zombie process because it's kind of still alive when it shouldn't be. It should be dead.
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