Articles of the VPS column:

Linux is a system equipped with countless diagnostic tools that can be used with a command line interface (CLI) allowing sysadmins to identify and solve problems and malfunctionings. Regardless of the typical limitations of a textual environments, these supporting programs are really powerful as they can be invoked by simple commands or placed into automated scripts. In this article we’ll cover some of the most common: top, ps and netstat.

top and htop: processes, workload and memory under control

top is the command used to identify processes, a clear indicator of the system health state and allows to check parameters such as CPU and memory usage percentage in addition to the actual state of active processes.

01 top

Once invoked the command from a cli, a schematic table is displayed with information organized by columns. Despite the sight might be dedicated only to the content of the table, it’s quite important to observe those parameters indicated above it.

Indeed a common situation where a decrease of overall performances can be identified by observing the trend (probably growing) of the load average parameter despite a scarce usage of CPU and RAM. An increase of the wait state (wa) parameter is an indicator of the system difficulty to process instructions.

By analyzing the lower column we can note that processes are represented by their PID (Process IDentifier), while the following columns indicate the user that started the process, its priority, resource usage percentages and other additional parameters.

The graphical level offered by the Linux Shell is in any case quite limited, so an evolute version of top has been implemented: htop. Unlike top, this command is not natively present in Linux, it must be installed using the package manager of your favourite distro.
htop shows up with a significantly evolute graphical dress, still based on the concept of Text User Interface (TUI).

02 htop

In the upper part, a colored graph has been inserted to show the system load level, and the menu system allows to navigate inside processes, order them, apply filters on the list and perform researches. The processes interaction level has been improved, too: itìs now possible to increase and decrease the priority of a process, in addition to stop it.

ps: a tree of applications

Regarding processes monitoring, the reference command is ps: ps is a tool that allows to visualize a snapshot of executing processes on a user and system basis. Adding the -faxu options shows the process tree and sub-processes with useful information such as user, PID and state of the process.

03 psfaxu

netstat: who’s connecting to what?

Most active processes in a Linux system establish, or at least use during their activities, one of more network ports. Some signals of a bad system behaviour are often identified by a variation of the state of active connections on a service level, and on usage level too. The nestat command invoked with the –putln shows the actual oper ports and the related service or process.

04 netstat1

The service usage state on a network level is another potentially useful element to diagnose performance decreases. Lastly, netstat can be piped with the commands grep or wc -l which allows to apply filter on the results and to make a count of the occurrences of established connections.

05 netstat2

banner eng

fb icon evo twitter icon evo

Word of the Day

The term Edge Computing refers, when used in the cloud-based infrastructure sphere, the set of devices and technologies that allows...

>

The acronym SoC (System on Chip) describes particular integrated circuit that contain a whole system inside a single physical chip:...

>

The acronym PtP (Point-to-Point) indicates point-to-point radio links realized with wireless technologies. Differently, PtMP links connects a single source to...

>

Hold Down Timer is a technique used by network routers. When a node receives notification that another router is offline...

>

In the field of Information Technology, the term piggybacking refers to situations where an unauthorized third party gains access to...

>
Read also the others...

Download of the Day

Netcat

Netcat is a command line tool that can be used in both Linux and Windows environments, capable of...

>

Fiddler

Fiddler is a proxy server that can run locally to allow application debugging and control of data in...

>

Adapter Watch

Adapter Watch is a tool that shows a complete and detailed report about network cards. Download it here.

>

DNS DataView

DNS DataView is a graphical-interface software to perform DNS lookup queries from your PC using system-defined DNS, or...

>

SolarWinds Traceroute NG

SolarWinds Traceroute NG is a command line tool to perform advanced traceroute in Windows environment, compared to the...

>
All Download...

Issues Archive

  •  GURU advisor: issue 21 - May 2019

    GURU advisor: issue 21 - May 2019

  • GURU advisor: issue 20 - December 2018

    GURU advisor: issue 20 - December 2018

  • GURU advisor: issue 19 - July 2018

    GURU advisor: issue 19 - July 2018

  • GURU advisor: issue 18 - April 2018

    GURU advisor: issue 18 - April 2018

  • GURU advisor: issue 17 - January 2018

    GURU advisor: issue 17 - January 2018

  • GURU advisor: issue 16 - october 2017

    GURU advisor: issue 16 - october 2017

  • GURU advisor: issue 15 - July 2017

    GURU advisor: issue 15 - July 2017

  • GURU advisor: issue 14 - May 2017

    GURU advisor: issue 14 - May 2017

  • 1
  • 2
  • 3
  • BYOD: your devices for your firm

    The quick evolution of informatics and technologies, together with the crisis that mined financial mines, has brought to a tendency inversion: users that prefer to work with their own devices as they’re often more advanced and modern than those the companies would provide. Read More
  • A switch for datacenters: Quanta LB4M

    You don’t always have to invest thousands of euros to build an enterprise-level networking: here’s our test of the Quanta LB4M switch Read More
  • Mobile World Congress in Barcelona

    GURU advisor will be at the Mobile World Congress in Barcelona from February 22nd to 25th 2016!

    MWC is one of the biggest conventions about the worldwide mobile market, we'll be present for the whole event and we'll keep you posted with news and previews from the congress.

    Read More
  • 1