9. Process States

Let's take a look at the ps aux command again:

$ ps aux

In the STAT column, you'll see lots of values. A linux process can be in a number of different states. The most common state codes you'll see are described below:

• R: running or runnable, it is just waiting for the CPU to process it


• S: Interruptible sleep, waiting for an event to complete, such as input from the terminal


• D: Uninterruptible sleep, processes that cannot be killed or interrupted with a signal, usually to make them go away you have to reboot or fix the issue


• Z: Zombie, we discussed in a previous lesson that zombies are terminated processes that are waiting to have their statuses collected


• T: Stopped, a process that has been suspended/stopped