htop

htop is an interactive, text-based process viewer for Linux. It is frequently preferred over top because it offers a much more user-friendly, colorful interface, allows vertical and horizontal scrolling to see all processes and full command lines, and supports mouse interactions in modern terminal emulators.

Note: htop is often not installed by default on many minimal Linux distributions. You may need to install it via your package manager (e.g., apt install htop or yum install htop).

Basic Syntax

htop [OPTIONS]

Common Flags/Options

Option	Description
-d DECISECONDS	Delay between updates, in tenths of seconds.
-u USERNAME	Show only processes owned by a specific user.
-p PID,PID...	Show only the given PIDs.
-C	Disable color output.

Interactive Commands (While htop is running)

The bottom of the htop screen displays the function keys for common actions:

Key	Action
F1 / h	Help menu.
F2 / S	Setup menu (configure meters, display options, and colors).
F3 / /	Search for a process by name.
F4 / \	Filter processes by name.
F5 / t	Toggle tree view (shows parent/child relationships).
F6 / < >	Select the sort column (CPU, Memory, User, etc.).
F7 / ]	Decrease the priority (nice value) of the selected process.
F8 / [	Increase the priority (nice value) of the selected process.
F9 / k	Send a signal (usually SIGTERM or SIGKILL) to the selected process.
F10 / q	Quit htop.
Space	Tag a process (allows you to apply actions to multiple processes at once).

Real-world Examples

1. Launching htop

Simply running the command gives you the full interactive dashboard.

htop

2. Searching and Filtering

When you have hundreds of processes, finding one can be hard.

• Press F4, type "nginx", and press Enter. Now you will only see nginx processes.
• Press F5 to see the hierarchy of those nginx master and worker processes.

3. Killing a misbehaving process easily

1. Open htop.
2. Use the arrow keys (or click with your mouse) to highlight the frozen process.
3. Press F9.
4. A menu of signals will appear on the left. Press Enter to send the default SIGTERM (15), or select SIGKILL (9) if it refuses to close.