What Is htop: Linux Interactive Process Viewer

This article provides an essential overview of htop, a cross-platform interactive system-monitoring and process-viewer tool for Unix-like systems. You will learn what htop is, how it improves upon the traditional top utility, its primary features, and basic navigation shortcuts to help you effectively monitor system resources and manage running processes.

Understanding htop

htop is a text-mode, interactive process viewer designed as a modern replacement for the classic Unix top command. Written in C using the ncurses library, it gives system administrators and developers a real-time, visual representation of running processes and system resource utilization directly in the terminal.

Unlike older monitoring tools, htop offers a full-color, intuitive user interface that makes it easy to track CPU usage per core, system memory, swap space, and uptime at a single glance. Users can scroll through the entire process list both vertically and horizontally to view complete command lines without truncation.

Key Features of htop

  • Visual Meters: Displays real-time, color-coded meters for individual CPU cores, memory consumption, swap usage, and system tasks.
  • Mouse Support: Allows users to select processes, scroll, and click menu buttons directly in terminals that support mouse events.
  • Process Management: Lets you kill or change the priority (renice) of a process without manually looking up or typing its Process ID (PID).
  • Tree View: Organizes running processes in a hierarchical parent-child tree view to easily identify which parent service spawned a specific task.
  • Filtering and Searching: Provides instant search and filtering mechanisms to isolate specific processes by name or user.

For complete installation instructions, configuration flags, and source details, consult the htop Command line tool documentation website.

Essential Navigation Shortcuts

Once htop is running, you can interact with it using dedicated keyboard shortcuts:

  • F1 (or ?): Opens the help menu and displays all available keybindings.
  • F2 (or S): Enters the setup screen to customize display meters, columns, and color schemes.
  • F3 (or /): Searches for a specific process by name.
  • F4 (or ): Filters the process list dynamically to show only matching entries.
  • F5 (or t): Toggles between the standard list view and the hierarchical tree view.
  • F6 (or < / >): Selects a column to sort processes by (such as CPU%, MEM%, or PID).
  • F9 (or k): Sends a kill signal (such as SIGTERM or SIGKILL) to the currently highlighted process.
  • F10 (or q): Safely exits the application and returns to the shell.