# Linux commands: top

> Learn how the Linux top command shows running processes in real time, with live CPU, memory, and system load, and how top -o mem sorts them by memory use.

Author: [Flavio Copes](https://flaviocopes.com/about/) | Published: 2020-09-08 | Topics: [CLI](https://flaviocopes.com/tags/cli/) | Canonical: https://flaviocopes.com/linux-command-top/

A quick guide to the `top` command, used to list the processes running in real time

The `top` command is used to display dynamic real-time information about running processes in the system.

It's really handy to understand what is going on.

Its usage is simple, you just type `top`, and the terminal will be fully immersed in this new view:

![Terminal window showing top command output with system stats and process list sorted by CPU usage](https://flaviocopes.com/images/linux-command-top/Screen_Shot_2020-09-03_at_11.39.53.png)

The process is long-running. To quit, you can type the `q` letter or `ctrl-C`.

There's a lot of information being given to us: the number of processes, how many are running or sleeping, the system load, the CPU usage, and a lot more.

Below, the list of processes taking the most memory and CPU is constantly updated.

By default, as you can see from the `%CPU` column highlighted, they are sorted by the CPU used.

You can add a flag to sort processes by memory utilized:

```bash
top -o mem
```

> This command works on Linux, macOS, WSL, and anywhere you have a UNIX environment