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install htop

Every system administrator likes to use some of the more commonly used commands. Today I recommend htop as an alternative to the top command. To use the htop command normally , you need to install it first.

# Installation epel source (also called repository)
dnf -y install epel-release
# Generate cache
dnf makecache
# Install htop
dnf -y install htop

Use htop

You only need to type htop in the terminal, and the interactive interface is as follows:

0[ |||                      3%]     Tasks: 24, 14thr; 1 running
1[ |                        1%]     Load average: 0.00 0.00 0.05
Mem[ |||||||           197M/8G]     Uptime: 00:31:39
Swap[                  0K/500M]
PID   USER   PRI   NI   VIRT   RES   SHR   S   CPU%   MEM%   TIME+   Commad(merged)
...

F1Help F2Setup F3Search F4Filter F5Tree F6SortBy F7Nice F8Nice+ F9Kill F10Quit

Top Description

  • The top 0 and 1 indicate the number of your CPU cores, and the percentage indicates the occupancy rate of a single core (of course, the total occupancy rate of the CPU can also be displayed)

    • The different colors of the progress bar indicate the percentage of different process types:

      Color Description
      Blue Percentage of CPU used by low-priority processes
      Green Percentage of process CPU owned by ordinary users
      Red Percentage of CPU used by system processes
      Orange Percentage of CPU used by IRQ time
      Magenta Percentage of CPU used by soft IRQ time
      Gray Percentage of CPU occupied by IO waiting time
      Cyan Percentage of CPU consumed by Steal time

  • Tasks: 24, 14thr; 1 running, process information. In my example, it means that my current machine has 24 tasks, which are divided into 14 threads, of which only 1 process is in a running state.

  • Mem memory and swap information. Similarly, use different colors to distinguish:
Color Description
Blue Percentage of memory consumed by the buffer
Green Percentage of memory consumed by the memory area
Orange Percentage of memory consumed by the cache area
  • Load average, the three values ​​respectively represent the average load of the system in the last 1 minute, the last 5 minutes, and the last 15 minutes
  • Uptime, which means the running time after booting

Process information description

  • PID-Process ID number

  • USER-the owner of the process

  • PRI-Display the process priority as seen by the Linux kernel
  • NI-displays the process priority of reset by normal user or root super user

  • VIRI-virtual memory being consumed by a process

  • RES-physical memory being consumed by a process

  • SHR-shared memory being consumed by a process

  • S-The current state of the process, there is a special state to pay attention to! That is Z (zombie process). When there are a large number of zombie processes in the machine, it will affect the performance of the machine.

  • CPU%-Percentage of CPU consumed by each process

  • MEM%-Percentage of memory consumed by each process

  • TIME+-shows the running time since the process was started
  • Commad-the command corresponding to the process

Shortcut key description

In the interactive interface, press the F1 button to see the corresponding shortcut key description.

  • The up, down, left, and right direction keys can scroll through the interactive interface, and space can mark the corresponding process, which is marked in yellow.
  • The N button, the P button, the M button and the T button are respectively PID, CPU%, MEM%, TIME+ is used for sorting. Of course, you can also use the mouse to click to sort in ascending or descending order of a certain field.

Other commonly used

To manage the process, use the F9 button to send different signals to the process. The list of signals can be found in kill -l. The more commonly used ones are:

Signal Description
1 Let the process shut down immediately, and then restart after re-reading the configuration file
9 Used to immediately end the running of the program, used to forcibly terminate the process, similar to the forced end in the windows taskbar
15 The default signal for the kill command. Sometimes if a problem has occurred in the process and the process cannot be terminated normally with this signal, we will try signal 9

End

htop is much easier to use than the top that comes with the system, it is more intuitive, and it improves daily use greatly. This is why usually the first thing after installing the operating system the author installs it.

Last update: January 5, 2022

Author: tianci li

Contributors: Steven Spencer

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