12 TOP Command Examples in Linux

This is the part of our on-going series of commands in Linux. We have covered basic ls command and cat command. In this article, we are trying to explore top command which is one of the most frequently used commands in our daily system administrative jobs. top command displays processor activity of your Linux box and also displays tasks managed by kernel in real-time. It’ll show processor and memory are being used and other information like running processes. This may help you to take correct action. top command found in UNIX-like operating systems.

Linux Top Command Examples

Linux Top Command Examples

You might also be interested in following tutorials :

  1. Htop (Linux Process Monitoring) tool for RHEL, CentOS & Fedora
  2. Iotop (Monitor Linux Disk I/O) in RHEL, CentOS and Fedora

1. Display of Top Command

In this example, it will show information like tasks, memory, cpu and swap. Press ‘q‘ to quit window.

# top
Linux Top Command

Linux Top Command

2. Sorting with -O (Uppercase Letter ‘O’).

Press (Shift+O) to Sort field via field letter, for example press ‘a‘ letter to sort process with PID (Process ID).

Sorting Process ID's with Top

Sorting Process ID’s with Top

Type any key to return to main top window with sorted PID order as shown in below screen. Press ‘q‘ to quit exit the window.

Sorting Process ID's

Sorting Process ID’s

3. Display Specific User Process

Use top command with ‘u‘ option will display specific User process details.

# top -u tecmint
Top with Specific User Processes

Top with Specific User Processes

4. Highlight Running Process in Top

Press ‘z‘ option in running top command will display running process in color which may help you to identified running process easily.

Top Process with Colorful

Top Process with Colorful

5. Shows Absolute Path of Processes

Press ‘c‘ option in running top command, it will display absolute path of running process.

Top with Specific Process Path

Top with Specific Process Path

6. Change Delay or Set ‘Screen Refresh Interval’ in Top

By default screen refresh interval is 3.0 seconds, same can be change pressing ‘d‘ option in running top command and change it as desired as shown below.

Top - Set Refresh Time

Top – Set Refresh Time

7. Kill running process with argument ‘k’

You can kill a process after finding PID of process by pressing ‘k‘ option in running top command without exiting from top window as shown below.

Top - Kill Process ID

Top – Kill Process ID

8. Sort by CPU Utilisation

Press (Shift+P) to sort processes as per CPU utilization. See screenshot below.

Top - High CPU Utilization

Top – High CPU Utilization

9. Renice a Process

You can use ‘r‘ option to change the priority of the process also called Renice.

Top - Renice Process

Top – Renice Process

10. Save Top Command Results

To save the running top command results output to a file /root/.toprc use the following command.

# top -n 1 -b > top-output.txt
Top Command Save Results

Top Command Save Results

11. Getting Top Command Help

Press ‘h‘ option to obtain the top command help.

Top Command Help

Top Command Help

12. Exit Top Command After Specific repetition

Top output keep refreshing until you press ‘q‘. With below command top command will automatically exit after 10 number of repetition.

# top -n 10

There are number of arguments to know more about top command you may refer man page of top command. Please share it if you find this article useful through our comment box below.

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80 Responses

  1. Sairam says:

    much usefull and clear explanation of the command with screenshots..also simple and easy to understand

  2. Victor says:

    Can someone please help me to gather only the top 20 processes information from the top command into a file after each 60 seconds of interval?

  3. harsha says:

    Excellent Ravi,

    Thank you for you information..

  4. Abhishek Sharma says:

    Hi Ravi

    Point 10 saving top’s output to a file saves it configuration instead.
    Please suggest in that,correct it if its wrong.
    PFB output.

    RCfile for “top with windows” # shameless braggin’
    Id:a, Mode_altscr=0, Mode_irixps=0, Delay_time=3.000, Curwin=0
    Def fieldscur=AEHIOQTWKNMbcdfgjPlrsuvyzX
    winflags=62777, sortindx=15, maxtasks=0
    summclr=1, msgsclr=1, headclr=3, taskclr=1
    Job fieldscur=ABcefgjlrstuvyzMKNHIWOPQDX
    winflags=62777, sortindx=0, maxtasks=0
    summclr=6, msgsclr=6, headclr=7, taskclr=6
    Mem fieldscur=ANOPQRSTUVbcdefgjlmyzWHIKX
    winflags=62777, sortindx=13, maxtasks=0
    summclr=5, msgsclr=5, headclr=4, taskclr=5
    Usr fieldscur=ABDECGfhijlopqrstuvyzMKNWX
    winflags=62777, sortindx=4, maxtasks=0
    summclr=3, msgsclr=3, headclr=2, taskclr=3

    • Ravi Saive says:

      @Abishek,

      Yes its just only saves top configuration, to save the top running output to a file use the following command.

      # top -n 1 -b > top-output.txt
      
  5. LTTR says:

    This is very helpful. Is there a guide to definitions of all the top headers? i.e. PR, NI etc.

  6. Alex says:

    This was VERY helpful for my OCR Computing Controlled Assesment, thanks!

  7. TecGeeks says:

    If server has multiple processor suppose (3) is CPU usage will show 300% in top command or consolidate under 100%, and How can we see individual CPU Usage if server has multiple processors

  8. Srinivas says:

    Ravi, it’s good collection of examples. Each and every details covered. Want to see more of this kind of work

  9. Fatiha says:

    Thank you very much ! Very helpful and useful.

    Now I use : top -u myUser

  10. Prince says:

    Hello, I was wondering if anyone could help me by evaluating the usefulness of the top command to a technician when using it with ps and kill in order to investigate a system that is misbehaving. Thank you.

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