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htop is an interactive process viewer for Linux. Install it with sudo apt install htop (Ubuntu/Debian) or from EPEL with sudo dnf install htop (AlmaLinux/Rocky), then run htop. The top shows one bar per CPU core, memory, swap, tasks and load average; below is every process. Press P to sort by CPU, M by memory, F4 to filter, F9 to kill and q to quit.

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Before you start

  • Connect with SSH.
  • Commands use sudo. If you are logged in as root, leave it out.
  • htop only reads information unless you press a key that changes something (kill, renice). Start it with htop --readonly if you want to rule that out.

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How to install htop

Check the version with htop --version. Ubuntu 24.04 ships htop 3.3.0.

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How to read the htop screen

Run htop. The screen has a header (meters) and a process list.
The bars use colours for different kinds of use. Press F1 to see the legend for your colour scheme. It reads CPU usage bar: [low/normal/kernel/guest used%] and Memory bar: [used/shared/compressed/buffers/cache used/total]. A CPU bar that is mostly kernel time or a memory bar that is mostly used (not cache) is worth a closer look.

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What the htop columns mean

CPU% above 100 is normal. On a 4-core server, one process can reach 400%. It means the program uses several cores, not that something is broken.

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How to find the busiest processes

1

Sort by CPU or memory

Press P to sort by CPU%, M by MEM% or T by TIME+. Press F6 to pick any column, and I to reverse the order.
2

Filter the list

Press F4 and type part of a name, for example nginx. Only matching processes stay on screen. Press F4 then Esc to clear it.
3

See which program started what

Press F5 for the tree view. Child processes appear under their parent, which helps with web servers, PHP-FPM pools and game server wrappers.
4

Show only one user

Press u and choose a user, for example www-data or alex.
5

Hide threads

Press H to hide user threads so each program appears once.
You can also start htop already sorted or filtered:

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How to kill or slow down a process in htop

1

Select the process

Move to it with the arrow keys, or press F3 and type part of its name.
2

Send a signal

Press F9. SIGTERM (15) is selected first and asks the program to close cleanly. Press Enter. Use SIGKILL (9) only if it doesn’t stop.
3

Or lower its priority

Press F8 to raise its nice value so other processes get the CPU first. Only root can lower the nice value again (F7).
Killing the wrong process can stop your website, database or SSH session. Run htop as your normal user when you only want to look, and stop services with sudo systemctl stop name rather than F9. See kill a process.

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How to check it worked

After a kill or priority change, the process should vanish from the list or show the new NI value. To confirm from the command line:

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Frequently asked questions

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What is the difference between top and htop?

top is installed on every Linux server. htop adds colour meters, scrolling, mouse support, a tree view and kill or renice without typing a PID. Both read the same kernel data.

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Why does htop show memory almost full?

Check the used part of the bar (F1 shows its colour), not the total. Linux uses spare RAM as cache and frees it on demand. free -h shows the real headroom in the available column. See check memory usage.

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Where does htop save my settings?

In ~/.config/htop/htoprc. Change settings with F2 (Setup) rather than editing the file, because htop overwrites it on exit.

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Why is a process stuck in state D?

D means it is waiting for disk or network I/O and can’t be killed until that finishes. Check the disk with iostat and iotop.

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Does htop slow my server down?

Very little. If you leave it open for a long time, raise the refresh delay with htop -d 30 (3 seconds).

VPS and dedicated server guides

Every server guide in one place.

Find what is using CPU

Track down a busy process.

Check memory usage

free, available memory and swap.

What is load average?

Read the three numbers.

Kill a process

kill, pkill and killall.

VPS Panel resource graphs

CPU, memory and network history.
Checked against the htop manual and the Fedora EPEL package list on 4 November 2026; commands tested on Ubuntu 24.04 LTS with htop 3.3.0. Commands can differ on other distributions or releases.

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Last Updated: November 2026