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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

Exercise

Take a look at the running processes on your system and check out their process states.

Quiz Questions

Click the right arrow to view the answers

What STAT code is used to represent an uninterruptible sleep? D