Note: The language in some of the screenshots is not in English but the command we have executed in English language. You just need to run the given commands and execution in your screen will show based on your preferred language set on the system,

Install Zabbix on Ubuntu 16.04

The first thing we have to do is update the system in order to have the latest security updates.

sudo apt update && sudo apt –y upgrade

With this composite command, we refresh the repository cache and at the same time say yes to updates.

Once you will enter sudo password in above screen, a series of transactions will be executed as shown in below screenshot.

Once we have the system updated, the next thing we need to do is to install a basic LAMP server to run the Zabbix and mysql frontend as database manager.

sudo apt install apache2 libapache2-mod-php7.0 mysql-server-5.7 mysql-client php7.0 php7.0-mysql php7.0-curl php7.0-json php7.0-cgi php-xml php-mbstring php-bcmath

Once you will execute above command, you will be getting a sequence of executions as shown in below image.

Once the LAMP server is installed, we must edit the php. ini file to set our time zone correctly. In my case “America/Caracas”.

sudo nano /etc/php/7.0/apache2/php.ini

Once you will execute above command, you will get below screen to edit the time zone. Inside the archive, we locate the part where the time zone is established and edit it with our own.

Now we will restart Apache service using below command..

sudo systmectl restart apache2.service

Now we must add the Zabbix repository, to do this we must download a. deb file hosted on their website.

wget http://repo.zabbix.com/zabbix/3.4/ubuntu/pool/main/z/zabbix-release/zabbix-release_3.4-1+xenial_all.deb

And then install it to add the repository.

sudo dpkg –i zabbix-release_3.4-1+xenial_all.deb

Now we must refresh the program sources cache and install zabbix packages. Run below command to update the repository.

sudo apt update

You can see the execution of above command.

Run below command to initiate the execution.

sudo apt install zabbix-server-mysql zabbix-frontend-php zabbix-agent

We can see the installation in below image.

Configure MySQL

In this step we must configure mysql, skip this if you already had an installation before.

sudo mysql_secure_installation

To the questions we must answer yes or no according to our needs. For this tutorial, the answers to these questions are no problem. The important thing is to remember the Mysql root password.

Then we must log in to Mysql when entering the command, we must enter the root password.

mysql –u root –p

Once inside, we must create the zabbix database.

CREATE DATABASE zabbix

We then create and give permission to a new Mysql user to use zabbix. This is a good security practice for our server.

GRANT ALL ON zabbix TO ‘zabbix’@localhost IDENTIFIED BY ‘zabbixpss’;

Replace’ zabbixpss’ with another username if you prefer, and’ zabbixpss’ with another password. you can see all above steps in below command.

Next we must “copy” the configuration of Mysql to the new zabbix user.

zcat /usr/share/doc/zabbix-server-mysql*/create.sql.gz | mysql –u zabbix –p

However at this point I got the error of “No database selected”. Don’t worry, we’ll figure it out. To fix error 1046, we must first copy and unzip the MySql creation file.

And then edit the “create.sql” file, we just must add USE zabbix; at the beginning of the file.

nano create.sql

Save and we will be able to import the file.

cat create.sql | mysql –u zabbix –p

This completes the configuration process of the database manager.

Now we proceed to edit the configuration file of zabbix to add the database parameters that the application will use.

sudo nano /etc/zabbix/zabbix_server.conf

Verify below parameters from below screenshot.

DBHost=localhost

DBName=zabbix

DBUser=zabbix

DBPassword=zabbixpss

These parameters are the ones that we have to locate in the archive and change for the positions.

Then we must restart Apache2 and Zabbix services.

sudo systemctl restart apache2.service
sudo systemctl restart zabbix-server.service

Configure Zabbix

Now, it’s ready. We have to go to our web browser and access from the ip address of the server computer.

http://IP_ADRESS/zabbix 

Then we proceed to configure it, pressing next. We check that all prerequisites are satisfied.

In this screen we must configure the database parameters that we have made in the previous steps.

Then you have to configure the server parameters. In this case, we leave it the same way.

In the end if everything is correct we should see a screen like this.

Finally we can now access through the following form:

Username: admin

Password: zabbix

And after that, we’ll have the main view with our zabbix running on the server.

As a conclusion we can say that Zabbix is a great open source application for server monitoring, its installation in server is relatively simple and is very useful to all system administrators.

Read More:

• How to Install and Use HTop on Linux system?
• Installing PgAdmin 4 on Debian Stretch
• RHEL Interview Questions and Answers

The post How to Install Zabbix on Ubuntu Server 16.04? appeared first on Techyaz.com.

LIST FILES IN LINUX: “ls” COMMAND 

As it was said, the command ls allows you to list files and folders of a specific path, is easy to use and is very useful and used in the daily work. The command has several options to improve the listings. In a terminal, we can invoke the help of the command ls in this way.

ls --help 

Above command will display all options available for ls command to list the files and folders. In this way we get the syntax of usage and options as output per terminal.

As all options will not cover in one single screenshot so i have scrolled the above screen and taken another screenshots to cover all options in screenshots that has been displayed below.

As we can see the documentation is extensive, but don’t worry we will examine the most useful and used options. The basic syntax of the command is:

ls [options] [file|dir]

Although it is possible to use ls from the most basic form only by typing:

#List files from your given directory.
ls

With this we only list the files that are in the directory where we are located in the terminal. For example, if we wanted to list everything in the root directory of our GNU/LINUX distribution it would be with the command:

#List everything in the root directory
ls /

It was easy, wasn’t it?

Most Important Options of the Command “ls”

ls as well as all GNU/LINUX commands have options that modify the basic command execution result. Here is a list of the most outstanding ones for this command.

 Examples of Command “ls”

Here i have given different examples of command ls that you can use to fulfill different requirements.

List Hidden Files 

We can use option -a if we want to list the hidden files of a specific folder, it would be enough to write:

ls –a path

In my case it would be something like that:

ls –a /home/angelo/

You can see all hidden files as well in above screenshot. We can identify hidden files by looking at the output as such files or folders start with dot (.).

Display Files with their Index Number

We can list files with their index number by running below command. To show files/folders with their index number we will use the option –i along with command ls. You can see i have used below command and output is showing in below image.

ls -i /home/angelo/
 

List Files with full Details (Permissions, Index no, Owner, Create Date etc.)

We can use ls command to display information such as permissions and owner of the folder or file. We will be using option -I to show complete information about files and folders as shown in below screenshot.

ls -l /home/angelo/

This output shows us more specific information about what we have in the folder: First it shows the permissions on the folder, its index number, the owner of the folder, who created the folder, its size in kb, the date it was modified and the folder name.

List Files or Folders in a Reverse Order

ls command also gives an option to sort files and folders in reverse order. We can use -r option to show files and folders in a reverse order as shown in below screenshot after running below command.

ls –r  /home/angelo/

List Subdirectories Recursively

We can List subdirectories recursively by adding the -R option with ls command.  It will display the contents of the directory subfolders. Run below command to display the result.

ls –R /home/angelo/

 Display list of Directories Only

We can use -d and an asterisk option to list and show only the directories. Have a look at below command that has displayed the list of directories under /home/angelo.

ls –d */home/angelo/

Display Files Sort by their File Size

Run below command to display files sort by file size. It is possible with the option –S.

ls -S /home/angelo/

Sort by Date/Time

We can option -t to display files sort by date/time. Run below command to see the output that is also showing in below screenshot.

ls –t /home/angelo/

Display Files as they were Created

Use option -U to show folders and files in no order at all. It will display just as they are created.

ls –U /home/angelo/

Sort by File Extension

We can use option -X with ls command to sort files by their extension names. You can see this in below screenshot.

ls –X /home/angelo/

Sort by Modified Files

We can use combination of options -ltr to show last modification file or directory date. Simply run below command to display the output.

ls -lrt

ls -lrt [path]

In conclusion we can say that the ls command, even when it is relatively easy to use, is one of the tools most used by system administrators.

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Read More:

• RHEL Interview Questions & Answers
• Linux User Administration – Add, Delete & Modify User Accounts
• Install HTop and Use it to Monitor Linux Processes
• How to Change Host Name of RHEL system?
• How to Reset or Change Linux User Account Passwords?

The post 11 Examples of ls Command to List Files in Linux appeared first on Techyaz.com.

HTOP is a process viewer on the terminal created for the entire Unix family but has great popularity within GNU/LINUX. The main advantages of this tool are that we can monitor processes, finalize and explore them all from the terminal which guarantees a minimum expenditure of resources.

How to Install Htop on Various Linux Systems?

We can install Htop from your sources or simply from pre-compiled packages. However, Htop is found in most GNU/LINUX distributions through its main repositories. Please have a look at the step by step process to install Htop on Debian, RHEL, Ubuntu and other Linux systems.

Install Htop on Debian 8 Jessie and Debian 9 Stretch

The first thing we need to do is login as root. Type su on your terminal window and press enter followed by typing its password.

su

Once you will be connected using su account, run below command to install Htop on Debian systems.

apt install htop

Install Htop on Ubuntu 14.04  and Ubuntu 16.04

Here, I will show you how to install Htop on Ubuntu servers. Installation of htop on Ubuntu is very much similar to installing it on Debian as we did in above section. In the case of Ubuntu, we must be root user to install htop. Type su and press enter followed by its password.

su

Once we will be connected using root user, we will proceed to install htop on Ubuntu by running below commands. A set of execution will start and execution will finish with its installation.

apt install htop

Install Htop on Fedora 26 and Fedora 27

There is little different way to install Htop on Fedora systems as we use dnf command to install it on fedora. Fedora users can easily install htop as following below steps. First we connect to root privileges using su account. Type su and its password.

su

Once we will be connected using su account, we can invoke dnf which is Fedora package manager. Run below dnf command to install htop on Fedora systems. A set of execution will start and finish with htop installation.

dnf install htop

Install Htop on Gentoo

For Gentoo we must also be root users. Write in a terminal:

su

Once we connected with root user permissions, we can install Htop by invoking Gentoo’s own package manager emerge. Run below command to start Htop installation on Gentoo system. A series of execution will start and finish with its installation.

emerge sys-process/htop

Install Htop on CentOS 7 and Red Hat Linux Enterprise

In the case of CentOS 7, we must first add the EPEL repository and then install it normally. First we logged in as root user to get installation privileges. Connect using su account by typing below command and its password.

su

Once logged in as root user, we proceed to download the package containing the EPEL repository:

wget http://mirror.pnl.gov/epel/7/x86_64/e/epel-release-7-5.noarch.rpm

And then install the downloaded package to add the EPEL repository:

rpm -Uvh epel-release-7-5.noarch.rpm

The next step is to “validate” the newly added repository by running below command.

yum repolist

And Finally we will install htop on RHEL and Centos by running below command.

yum install htop 

Basic use of HTOP

We have installed Htop on various Linux systems in above section. We must write the command htop To launch it. Here, it is not necessary to do it as root user. You can see i wrote htop on terminal window and press enter to get the Htop task manager screen in below image.

You will get below screen once you execute above command on your terminal screen.

It’s the initial screen. As we can see, it is very simple and easy to understand. We can have fun in three parts that we will study. In this “first part” we see the use of the processor and RAM by all processes along with other details. On the right side a small summary of them: how many tasks are running and the total active time.

“Second part” also you can say middle part is the main view where all the processes are showing. You can see this in below image.

This is where we have the information through columns that contain details about these processes. The columns are:

• PID: Displays the process identifier number.
• User: The user tells us that he has activated this process.
• PRI: It shows the priority with which the process is executed.
• NI: Shows the priority level
• VIRT: The number of virtual memory used by the process.
• RES: Used ram memory (Megabytes)
• SHR: Shared memory used
• S: Process status (Running, sleeping or zombie)
• CPU%: percentage of CPU used by the process
• MEM%: percentage of ram memory used by the process
• TIME+: Active life-time of the process
• Command: The command that executes the process.

So with this we have all the information of the processes that are running at that time.

The “last part” displays the tools provided by Htop for navigation. For example, allows us to search, sort the processes and the best, for me, the “kill” processes by using shortcut keys.

To kill a process we must navigate through the processes with the up and down keys, select it, press the F9 key, and choose the number that corresponds to the option of killing that serves us. I almost always use the 9th showing in below screen.

In conclusion we can say that Htop is a great tool to visualize the active and non-active processes in our Linux systems. Being terminal-based, it has the advantage of consuming virtually nothing in resources and helps us to close very heavy or unnecessary processes.

Here i have shown you how to install Htop on Red Hat, Ubuntu, Fedora and Debian systems and its uses. I hope you like this article. Please follow our Facebook page and Twitter handle to get latest updates.

Read More:

• How to Install Debian 9 Stretch?
• How to Install Zebbix on Ubuntu 16.4?
• How to Install RedHat Enterprise Linux?
• Installing Ubuntu 16.04 in Step by Step Process

The post How to Install Htop and Use it to Monitor Linux Processes? appeared first on Techyaz.com.