The ps command, which stands for Process Status, is one of the most popular commands used in today's environment. It displays the current processes running within a system; when we work within a Linux environment, we often overlook the underlying processes that make it all possible. All the information that the ps command displays comes from a very popular directory; namely, the /proc filesystem. The /proc filesystem is not actually a real filesystem, per se; it is in fact a virtual filesystem. It's loaded upon boot time, and you will find the /proc filesystem in almost every Linux distribution available today. Let's dive into the ps command.
To begin with, we can display any process that has started in the current shell:
[philip@localhost ~]$ ps
PID TTY TIME CMD
2220 pts/0 00:00:00 bash
95677 pts/0 ...