How to Use Top Command in Linux: Syntax and Examples

Use the top command in Linux to display real-time system processes and resource usage. Simply type top in the terminal to see CPU, memory, and process details updating live.

Syntax

The basic syntax of the top command is simple and can include options to customize the display.

• top: Starts the command with default settings.
• -d seconds: Sets the delay between screen updates.
• -p pid: Shows only the process with the specified PID.
• -n iterations: Limits the number of updates before exiting.

bash

top [-d seconds] [-p pid] [-n iterations]

Example

This example runs top with a 3-second update delay and shows only the process with PID 1234, refreshing 5 times before exiting.

bash

top -d 3 -p 1234 -n 5

Output

top - 15:30:00 up 1 day,  2:34,  1 user,  load average: 0.00, 0.01, 0.05

PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
1234 user      20   0  123456  23456   3456 S   0.0  0.1   0:00.01 example_process

(top exits after 5 updates)

Common Pitfalls

Common mistakes when using top include:

• Not running top with sufficient permissions to see all processes.
• Expecting top to exit automatically without using the -n option.
• Confusing the update delay -d with the number of iterations -n.

Always use Ctrl+C to exit top if you run it without the -n option.

bash

top -d 5
# This runs indefinitely until stopped manually

# Correct way to run for 3 updates:
top -d 5 -n 3

Quick Reference

Option	Description
-d seconds	Set delay between updates
-p pid	Show only specified process ID
-n iterations	Number of updates before exit
-b	Batch mode for logging
-u user	Show processes for a specific user

Key Takeaways

Run top in terminal to see live system process info.

Use -d to change update speed and -n to limit updates.

Press Ctrl+C to exit top if running indefinitely.

Use -p to focus on a specific process by PID.

Running top as root shows all system processes.