htop

An interactive process viewer that allows dynamic observation of system processes.

Description

The htop command is an interactive process viewer for Linux systems. It is a text-mode application (run in a console or X terminal) and requires the ncurses library.

Compared to the traditional top command, htop is more user-friendly. It allows interactive operations, supports color themes, enables horizontal and vertical scrolling of the process list, and supports mouse operations.

Advantages of htop over top:

• Scroll the process list horizontally and vertically to see all processes and complete command lines.
• Starts faster than top.
• No need to enter the PID to kill a process.
• Supports mouse operations.
• top is generally more cumbersome to use.

Disadvantages of top:

• Only supports keyboard operations.
• Display is relatively monotonous.

htop Official Website: http://htop.sourceforge.net/

htop Installation

In most Linux distributions, htop is not pre-installed. However, as one of the most popular utilities, you can find it in the default repositories of almost every Linux distribution.

For Debian/Ubuntu-based systems:

sudo apt install htop

For Fedora:

sudo dnf install htop

For CentOS or RedHat:

sudo yum install htop

A Snap package is also available:

sudo snap install htop

If you are using other distributions or want to build from source, you can use wget to download and install. This requires wget and cmake.

wget https://github.com/htop-dev/htop/archive/refs/tags/3.2.2.tar.gz
tar -zxvf 3.2.2.tar.gz
cd htop-3.2.2/
./autogen.sh && ./configure
make
sudo make install

Refer to the htop GitHub page for detailed instructions.

Note: By default, htop installs to /usr/local. To install to a different path, use the --prefix flag during configuration: ./configure --prefix=/some/path.

Syntax

htop

Options

-C --no-color               Use a monochrome color scheme
-d --delay=DELAY            Set the delay between updates, in tenths of a second
-s --sort-key=COLUMN        Sort by column (try --sort-key=help for a list)
-u --user=USERNAME          Show only processes for a specified user
-p --pid=PID,[,PID,PID...]  Show only specific PIDs
-h --help                   Print help message
-v --version                Print version information

Examples

• -C option: Set the interface to no color.
• -d option: Set the refresh interval in seconds. For example, htop -d 10 refreshes every 10 seconds.
• -s option: Sort by a specified column. For example, htop -s PID sorts the list by Process ID.
• -u option: Display process information for a specific user. For example, htop -u test shows only processes owned by the user "test".

Interactive Commands

h, ?    F1: View htop help/manual
S       F2: Setup
/       F3: Search for a process
\       F4: Filter processes by keyword
t       F5: Tree view
<, >    F6: Select sorting method
[       F7: Decrease nice value (increase priority)
]       F8: Increase nice value (decrease priority)
k       F9: Kill selected process
q       F10: Quit htop

/ : Search characters
h : Show help
l : List open files for a process (requires lsof)
u : Show processes for a specific user
U : Untag all processes
s : Trace system calls with strace
t : Toggle tree view

H : Show/hide user threads
I : Invert sort order
K : Show/hide kernel threads    
M : Sort by memory usage
P : Sort by CPU usage    
T : Sort by running time

Up/Down or PgUp/PgDn: Move selection
Left/Right or Home/End: Scroll process list
Space: Tag/Untag a process (commands like "kill" apply to all tagged processes)

htop Settings

Click "Setup" or press F2 to enter the htop configuration page.

1. Meters

Configure display information at the top. It's divided into "Left column" and "Right column". Select items from "Available meters" and press F5 to add to the left or F6 to add to the right. You can choose display modes like LED, Bar, or Text.

2. Display options

Select content to display. Press Space to toggle (x means selected). Press F10 to save.

3. Colors

Set the interface color scheme.

4. Columns

Add or remove columns. Use F7/F8 to move items up/down, F9 to remove, and F10 to save. You can add columns like PPID or PGRP based on your needs.

F3 Search Process Press F3 or "/" to enter search mode. Type the process name, and matches will be highlighted.

F4 Filter Case-insensitive fuzzy search. Only processes matching the keyword will be displayed.

F5 Tree View Displays processes in a parent-child hierarchy.

F6 Sort Choose the sorting criteria (e.g., CPU%, MEM%, PID).

F7, F8 Adjust Nice Value F7 decreases the nice value (increases priority), and F8 increases it (decreases priority). Range is -20 to 19.

F9 Kill Process Select a process and press F9 to send a signal (default is SIGTERM) to terminate it.

F10 Quit Exit htop.