Linux htop Command Examples

Example 1: Launch htop

htop

Launches htop with default settings, displaying CPU, memory, swap usage, and a list of processes with columns for PID, user, priority, CPU/memory usage, and command.

Sample Output: Interactive interface with real-time updates. Use arrow keys to navigate, F10 or q to quit.

Example 2: Filter Processes by User

htop -u username

Displays only processes owned by the specified user (replace username with an actual username, e.g., john).

Sample Output: htop interface shows only processes for the specified user, useful for isolating user-specific resource usage.

Interactive Tip: Press F4 in htop to filter interactively by typing a keyword.

Example 3: Sort Processes by a Specific Column

htop --sort-key CPU

Launches htop with processes sorted by CPU usage in descending order. Other sort keys include MEM, PID, TIME, etc.

Sample Output: Processes are displayed with the highest CPU-using process at the top.

Interactive Tip: Press F6 to select a sort column interactively.

Example 4: Display Tree View

htop --tree

Shows processes in a hierarchical tree view, grouping child processes under their parents, making it easier to see process relationships.

Sample Output: htop interface with processes indented to show parent-child relationships, e.g., a web server and its worker processes.

Interactive Tip: Press F5 to toggle tree view in htop.

Example 5: Show Specific Columns

htop

While not a direct command-line option, you can customize displayed columns interactively. Launch htop, press F2 (Setup), select "Columns," and add/remove columns like IO_READ, IO_WRITE, or COMMAND.

Sample Output: Updated htop interface with selected columns, e.g., showing I/O rates for processes.

Note: Changes are saved to ~/.config/htop/htoprc for future sessions.

Example 6: Kill a Process Interactively

htop

Launch htop, select a process with arrow keys, press F9, choose a signal (e.g., SIGTERM or SIGKILL), and confirm to terminate the process.

Sample Output: The selected process disappears from the htop interface after termination.

Warning: Use SIGKILL cautiously, as it forcefully terminates processes without cleanup.

Example 7: Change Process Priority

htop

Launch htop, select a process with arrow keys, press F7 to increase priority (lower nice value) or F8 to decrease priority (higher nice value).

Sample Output: The PRI or NI column updates to reflect the new priority value.

Note: Requires sufficient permissions (e.g., root for some changes). Negative nice values increase priority, while positive values decrease it.

Example 8: Limit Refresh Interval

htop -d 50

Sets the refresh interval to 5 seconds (50 tenths of a second). This reduces CPU usage for htop on systems where frequent updates are unnecessary.

Sample Output: htop interface updates every 5 seconds instead of the default 2 seconds.

Interactive Tip: Press + or - in htop to adjust the refresh interval dynamically.

Example 9: Display Only User Processes

htop -U

Shows only processes owned by the current user, excluding system processes, for a cleaner view.

Sample Output: htop interface lists only the current user’s processes, e.g., user applications and scripts.

Example 10: Save Configuration

htop

Launch htop, customize settings (e.g., columns, colors, sort order) via F2 (Setup), and save by exiting setup. Settings are stored in ~/.config/htop/htoprc.

Sample Output: No output. Future htop sessions load the customized settings.

Tip: Backup htoprc to preserve settings across systems or resets.