Monitor System Performance In Linux

Every time a program or command is run, a process is created for it. These processes are all unique and identified by the process identification (PID) that becomes allocated to it. Management of processes can help keep the system stable or help when the system becomes unstable. Here are some of the process management commands you use:

ps           Displays information about running processes

kill         Terminates a process

pgrep Finds a process based on its PID

pidof Displays all processes related to service or command

top         Monitors system resources 

renice  Adjust the priority of a particular process

To view process with more detailed information of the processes the root user currently owns, you can use the “ps u” command. Here, you see not only the PID, but also the CPU and memory utilization. A common set of options that usually use when working with the ps command is aux combined with the grep command to get detailed information about a particular process.

To terminate a process, we need to know the PID of the process. For example, if you want to stop the SSH service because it isn’t responding, you just have to look for the PID associated with the SSH daemon. As you can see, the PID of SSH service is 2162. To kill the process forcefully and effectively stop the SSH service, you can do the following:

There are two more other commands you can use to determine the PID(s) of a service or command.

With the top command you will have an overview of processes on the system, including memory usage, CPU utilization, and more.

You can use the renice command to give that particular process higher priority on the CPU. The priority values range from -20 (first priority) to 20 (dead last priority). Only the root user may set processes to use a priority under 0. For example, I change the priority of SSH service from 0 (default) to -2.

Have fun!