Normally the cat command is applied for basically three things in particular:

• Display the contents of a file
• Copy text files to another text file
• Append a text file’s contents to another text file

Being a UNIX command it is ported to all GNU/LINUX distributions and of course, it has options to expand and vary the power of the command itself.  Let’s see the output at the terminal if we do the following command:

cat --help

The command shows us a quick help on the cat command including its options.

The basic usage syntax is:

cat [OPTION] [FILE]…

And the list of commands is shown in this table:

Don’t worry; we’ll examine the most useful options with several examples.

Display Content of File

If we want to show the content of a text file, the syntax would be:

cat path_of_the_archive

I’m going to show the content of a file called file1.txt located in the Example folder. Run below command to display file1.txt content.

cat file1.txt

And there we have the content of the file shown on the terminal in above image.

If you would like to display the contents of several files, simply place them next. Run below command to display contents of two files file1.txt and file2.txt.

cat file1.txt file2.txt

The exit at the terminal would be as follows:

You can see the contents of both files one by one in above image.

Identify Specific File Content

As we can see in above image, it simply shows the contents of file 1 and when it ends, it immediately shows the content of file 2 as if they were “concatenated”. If you would like to know where the content of each file ends, then use the -e option to show a $ at the end of the file.

cat –e file1.txt file2.txt

Add Number of Lines in Output

If you want to display the number of lines along with the file content then you can show it by adding -n option. Run below command to display the line numbers while displaying the file content.

cat –n file1.txt file2.txt

Copy Contents of One file to Another

We can also copy the content of one text file to another using CAT command. Run below command to copy content of file1.txt to file4.txt.

cat file1.txt > file4.txt

In this case, the command reads the contents of file1.txt and overwrites the contents of the new file. If it does not exist, it is simply created. Now we can validate above command whether contents have been copied to not. Now we proceed to show the contents of file4.txt to verify that it made the “copy”. Display content of file4.txt by running below command.

cat file4.txt

We can see the content is same as file1.txt in above image.

Combine or Append the Content of One File to Another

The cat command also allows us to combine or append a text file data to another one, thanks to the operator >>

In this case, we will combine the content of file1.txt with that of file2.txt

cat file1.txt >> file2.txt

And then we check the contents of the file2.txt file to validate it.

cat file2.txt

We can see contents have been combined in to this file. Basically the command takes the content of file1.txt and places it at the end of the file2.txt file

As a conclusion we can say that the cat command is a useful and important command to work with text files in GNU/LINUX and everything about the terminal. It is very useful for managing service configuration files on a server.

I hope you like this article. Please follow us on our Facebook page and Twitter handle to get latest updates.

Read More:

• 11 Examples of ls command to List Files in Linux
• Add, Delete & Modify Linux User Accounts
• How to Reset or Change Linux User Passwords?
• How to Change Linux Server Name?

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USERS IN GNU/LINUX 

The first thing we need to know is that, in GNU/LINUX there are different types of users already predefined and each of them have different characteristics for the correct functioning of the system. The first of these is the root user.

Root user

The Root user is the administrator of the operating system, with all options and permissions to perform operations and changes in the system. Its main features are:

• It is the only user account with system-wide privileges.
• In charge of controlling the administration of user accounts.
• It is the only user that can stop the system.
• The root user can install, uninstall and update basic system programs and libraries.

In other words, the root user is the all-powerful user of the system.

Special Users 

They are also called users without login. Their roles in the system are determined by the addition of installed programs. They are distinguished by:

• They are created (usually) automatically at the time of Linux or application installation.
• It does not have all the privileges of the root user, but depending on the account they assume different root privileges.
• They are created when installing the system or any of its extra components.
• Some of them are: bin, daemon, adm, lp, sync, shutdown, mail, operator, squid, apache

Common Users 

These last users are us. That is, they are accounts that are created to use all accessible parts of the system, such as assigned programs and directories. They have a Home directory where they can easily access their documents and files.

• Such users have only full privileges in their working directory or HOME.
• They are used for individual users.
• These users do not have privileges to manage the system or install software. 

How to Create or Add USERS TO Linux Systems?

The adduser command is a “new” alternative to the useradd binary that allows us to add common users to our GNU/LINUX distribution. It is much more “friendly” and intuitive than useradd and allows us to add additional information about the new user. Here we will learn how to create user on Linux system.

In order to use the adduser command we must be root users, for that reason write the following command in a terminal

#Connect using su.
su

You need to write the root password then we can use adduser. The most basic way to use the adduser command is:

adduser new_user 

where new_user is the name of user account. With this “basic” form a new user is created and by giving Enter we are asked to enter the new password for this new user account.

Type the password for your new user account and press Enter. Prompt will ask you to reenter the same password. Re-enter the password and press enter button.

After that you will be asked for any additional information such as Full Name, phone number etc.

At the end, prompt will ask us to confirm the information provided. Type Y to proceed if all information is correct.

Now, as mentioned above, that is the most basic way to create a user but adduser also has options and alternatives to create users. These alternatives are given by the options that can be added to the command, some of them are:

adduser [--home DIR] [--shell SHELL] [--no-create-home] [--uid ID]
[--firstuid ID] [--lastuid ID] [--gecos GECOS] [--ingroup GROUP | --gid ID]
[--disabled-password] [--disabled-login] [--add_extra_groups] USER

You can see various options available with adduser command in above screenshot. Let’s look at example. If you would like to add a user named angelob, and set their home directory to /opt/angelob/ the the command will be as follows.

adduser --home /opt/angelob/ angelob

And then it will ask us for the new password and basic user information. This way you can add user to Linux system.

How to Delete Linux User Accounts? 

As in above section we have learnt how to create user on Linux system. Here i will explain how remove user from Linux system. Removing users from the Linux system is simple and the command to do so is userdel and has many fewer options to make the task. You can see the descriptions for this command in below image.

The easiest way to delete a user is to remove it by running below command. Here user is the name of user account.

#user is the name of user account.
userdel user

We can also delete your entire personal directory with the -r option. Run below command to do this.

userdel -r user

How to Modify Linux User Accounts? 

I have shown how to remove Linux user  in above section. Here, i will explain how to modify a Linux user. To modify users in the GNU/LINUX system we use the command usermod. We can see in the following image the possibilities shown in command:

For example, if we wanted to change the password of a created user, it would be as follows.

#user is the name of Linux user account.
usermod -p ‘new_password’ user

Obviously this method is not recommended because it leaves the password visible. Be careful. Read below article if you want to change your Linux user account password.

• How to Reset or Change User Password on RHEL?

Another useful example is to move the personal folder of the desired user to another one, for it we must combine the options -d and -m in the following way.

usermod -d /opt/angelob1/ -m angelob

With the rest of the options, we only have to place them according to our needs.

In conclusion we can say that the administration of GNU/LINUX users is a matter for system administrators, the subject is wide and with many options to take into account for the creation of them.

Adduser simplifies the creation of user accounts and usermod allows us to modify them in a very fast and dynamic way. And if a user has already completed his life cycle in the system, we can remove it with userdel.

I hope this small guide has been useful to understand a little bit about GNU/LINUX users, clarifying that the commands explained in the article can be used in all popular distributions such as Ubuntu, Red Hat, Suse, Debian and others.
I hope you like this article. Please follow our Facebook page and Twitter handle to get latest updates.

Read More:

• RHEL Interview Questions and Answers
• How to Change Hostname of RHEL system?
• How to Install and Use Htop to Monitor Linux Processes?
• Install Debian 9 Stretch in Step by Step Process

The post Linux User Administration – Add, Delete & Modify User Accounts appeared first on Techyaz.com.

Red Hat Linux Interview Questions and Answers

1. What is Red Hat Enterprise Linux?

Answer – It is a GNU/LINUX distribution created and developed by the multinational enterprise oriented company Red Hat, being the basis for deploying cloud applications, servers or data center.

2. Which is the package manager used by RHEL?

Answer – The package manager in RHEL is YUM.

3. How do I install a program in RHEL?

Answer – Installing a package or program in RHEL is simple thanks to YUM. With root permission we type in a terminal.

yum install package_name

4. How can I update the packages in RHEL?

Answer – Run below command to update all packages in your RHEL system.

yum upgrade

5. How can I remove the packages in RHEL?

Answer – Run below command to remove any package from RedHat Linux system.

#Make sure to change the name of package that needs to be removed.
yum remove package_name

6. How can I create a user in RHEL?

Answer – We can create a new user from the terminal with the command:

#Pass the user name in place of user_name 
useradd user_name

7. How can I change the user password?

Answer – The command that allows us to change the password of the active user is passwd. By entering the command in the terminal, you will be prompted for the current password and twice for the new password. Read below article to learn step by step process to change user as well as sudo passwords.

• How to Reset or Change User Password on RHEL?

8. How can I change the system language?

Answer- In RHEL, the system language can be changed using the following command:

localectl set-locale LANG=”xx_XX.utf8”

For example, if the system is in English and we want to change to German

localectl set-locale LANG=de_DE.utf8

Then simply restart the active session (not the system)

9. What is a GNU/LINUX service?

Answer – A service is a program that runs in the background, outside the interactive control of the users of the system.

10. How can I list the services that are running in RHEL?

Answer – This is very useful when managing systems in GNU/LINUX. We can list all the services that are running with the command:

systemctl -t service --state=active

If you want to check specific service running on RHEL then you can pass service name in above command. For example, i want to check SQL Server service running on my RHEL system then i will run below command. This command will show the output for only this service.

systemctl status mssql-server

11. How can I start or stop a service?

Answer – During the administration of a GNU/LINUX based server we will have to initialize and also stop services.

To initialize:

systemctl start name.service 

To Stop:

systemctl stop name.service

To Restart:

systemctl restart name.service

12. How do I know which version of the kernel I am using?

Answer – To know which version of the Linux Kernel we are using, just use the command:

uname –r

13. How can I add and remove kernel modules?

Answer – The kernel modules are small programs or libraries that are added to the kernel so that it can manage hardware devices. To add or remove it we use the command modprobe.

For example, to add a module:

modprobe module_name

And to remove a module

modprobe –r module_name

14. What is the file system RHEL uses?

Answer – The file system used by RHEL is XFS

15. How do I know how much space is available on my hard disk with RHEL?

Answer – This is useful to know when we are reaching the hard disk capacity. With the command:

df –h

16. Can I change hostname in RHEL?

Answer – Yes. There are multiple ways to change hostname of a RHEL system. For example if we want hostname to be example. com, we must write the following command in a terminal:

hostnamectl set-hostname example.com

I have explained it in below article in very details way. Have a look at this article to learn the process to rename or change the hostname of RHEL system.

• How to Change Hostname of RHEL system?

17. How do I know the IP address of the equipment in RHEL?

Answer – With the command:

nmcli dev show

We will not only be able to see the ip address, but also the complete information of all the network interfaces. You can read below article to learn how to check and change the IP address, subnet mask etc of a RHEL system.

• How to Find and Change IP Address, Subnet Mask and Default Gateway of RHEL system?

18. Can I install a Web server in RHEL?

Answer- Of course, we can install the web server we want: Apache, nGix or other.

19. After installing Apache2, where is the default Document Root located?

Answer – By default the apache2 DocumentRoot in RHEL sets it to /var/www/html/

20. How do I know which version of Red Hat Enterprise Linux is running the server?

Answer – Run the command in a terminal to get the RHEL version running on your system.

/etc/redhat-release

I hope you like this set of Linux Interview Questions and Answers. Please follow our Facebook page and Twitter handle to get latest updates.

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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.

Downloading Debian

To install Debian 9 Stretch, first we need to access the download section of the Debian website, and first choose how we want to download it.

There are multiple options to download the debian package. You can choose whatever is easiest for you. I almost always choose the method of downloading via Torrent because it is faster and helps not saturate the main distribution servers. I recommend this method. To download via Torrent, I recommend Deluge or Qbittorrent.

After that, we choose cd (smaller size and smaller packets included) or DVD (large size and more packets) and the processor architecture that is usually 64-bit. And finally burn it to a DVD or USB drive.

Install Debian 9 Stretch

Note: I always have to tell people that before they install a new operating system, try installing it on a virtual machine. This in order to minimize errors and loss of information. Once you are familiar with the process and satisfied with the result, you proceed to install it on the “real” computer.

Let’s install Debian 9 Stretch on our machine. This is the first image that Debian displays when you enter the installer. We choose Graphical install and press Enter as shown in below image. After that, we chose the language and our localization.

Once you choose graphical install from above image, you will get below image to select your preferred language. Here, i have chosen English as my language. You can go with your language.

Once you click on continue button after selecting the language, you will be getting next window to choose your time zone location . Here, choose your the location for which you want to display the server time. I have chosen united states time zone for myself.

Once you click on continue button of above image, next step will come to choose our “locals”. That is, the system’s regional configuration. After that we must choose the input language.

I have selected United States as locales and clicked on continue button to proceed. Now we have to choose keyboard language configuration (input language configuration). Here i have selected English.

Once you press continue button, the installer will start writing the changes that you have selected or entered during above steps. You can see this in below screenshot.

Once above changes will be set then next thing you’ll see about network configuration. We will enter the hostname and then the domain name. I have entered debian as hostname of this system. You can write your hostname as per your naming convention.

Next we need to type the domain of the system. Enter full domain name in which your server is hosted.

Once you will click at continue button, next window will come to set the root password. Enter the root password in below image.

Now it follows user creation and new user password creation. Set up a user and password in next windows. Enter the full name of your username in below image and click at continue button.

Now type your username that will be used to login to this server. I entered my first name as my username.

Once you will click at continue button after setting the username, next screen will come to set its password.

Then comes the delicate part of installing any operating system: Disk Partitioning. We can choose the option we like, but I like to have control of what partitioned so I choose manual.

In this window appears the hard disk of our computer, create a virtual disk from 0 and does not even have partitions but do not worry, see how it is done. Select the disc and click to continue.

As the disk is “new” it warns me that there is no partition table, but the installer offers to create it. We say yes.

Once you will press continue, below screen will come to proceed.

At this point we can create the first partition that we will use for the system as such. Select the free space and click on continue.  And then we enter the size. Debian also recommends a swap partition so we put a smaller size than the total.

Now we will allocate the size to this disk.

In the following windows we placed that the partition will be primary and created at the beginning of the free space.

Choose location of this new partition using below window.

After that, we must modify the file system type (Ext4) and the mounting point (/) and leave it as it is in the image. Select that we have finished defining partition and click on continue.

Then start creating the swap partition with the remaining disk space. Select the remaining free space and click on continue.

We then tell the installer that we want to create a new partition but this time it will be logical.

And in this step is where we define that it will be swap partition.

We say that we have finished defining the partition and click Continue to see the summary of the partition.

This way, a simple and basic partitioning in GNU/LINUX must remain: one partition for / and another for Swap. If you are installing this installation on a main computer and “real” and the hard disk must already be partitioned and what you should do is simply say where you want to install the system. Now we say that we have finished partitioning the disk and click Continue for the installer to make the changes.

After that Debian will ask us if we want to analyze another DVD, if we want to use a replica of beef and if we want to participate in an anonymous packet usage survey. In this tutorial, we use the DVD so to all questions I will answer NO.

Configure Popularity Contest.

And we come to the step of selecting the software to install. This is how it looks by default.

The software you choose will depend on you and your needs, for example for a production server you should not install graphical environment. There would be something like that.

In this case, I will choose MATE as my desktop environment. Once you have finished the installation process of the chosen software, you will ask us if we want to install the Boot Loader.

We say yes, and he’ll ask us where we want to be. Select your hard drive and click on continue.

After that we should see the window where the installation is finished and we can relocate the computer to use our brand-new Debian 9 Stretch.

Now your Debian 9 Stretch has been installed on your server. I hope you like this article. Please follow our Facebook page and Twitter handle to get latest updates.

Read More:

• How to Install RedHat Linux 7.3
• How to Install Ubuntu Server 16.04 

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PostgreSQL is for many the best in its area, and it is not the aim of this article to defend or support that theory, what we can say with all certainty is that it is one of the most robust and secure database handlers that exist. As if this were not enough, it has one of the most popular and complete graphical tools to manage it, such as pgAdmin.

As the project website says: “pgAdmin is the most popular and feature rich Open Source administration and development platform for PostgreSQL, the most advanced Open Source database in the world.” And of course we can install it in our preferred GNU/LINUX distribution. In this case we are going to install it in our Debian 9 Stretch a large GNU/LINUX distribution widely used in the server and database area.

Install pgAdmin 4 on Debian 9 Stretch

Note: In this tutorial it is assumed that you have postgreSQL installed, otherwise, we must install it. You can find the way of doing it in below link.

• How to Install PostgreSQL 10.1 on Debian 9 Stretch

Let’s get started. The first thing we have to do is add the postgreSQL apt repository. If you have installed postgreSQL with the tutorial we have attached above, you can skip these steps. Otherwise we must add it.

First we logged in as root user. Write su in your terminal screen along with its password and press enter to connect.

#Connect using root user
su

Now, use below command to create the pgdp.list file in the /etc/apt/source.list.d/ path.

nano /etc/apt/source.list.d/pgdg.list

Here, we will add the next line of code to the terminal screen that will come after executing above command.

deb http://apt.postgresql.org/pub/repos/apt/ stretch-pgdg main

Press ctrl + x to exit and select yes to save the changes.

Now import the repository signing key by running below commands on your terminal screen.

#Import the repository signing key
wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | apt-key add -

And to refresh the repository cache, just run the following command.

#Refresh the repository.
apt update

You can see all packages have been updated in above screenshot. Now we are ready to start installing pgAdmin 4.

Installing Dependencies and Creating the Virtual Environment

We must install the necessary dependencies to handle the package. They are basically Python dependencies that needs to be resolved before installing pgadmin package. Execute below command in your terminal before going to install pgadmin.

#Install Python dependency.
apt install virtualenv python-pip libpq-dev python-dev

Type Y and press enter to install this dependency. The next step will be to create the virtual environment. In this case we will create it on /home/Your_user/. Run below commands to get this done.

#Go to your directory.
cd /home/your_user/

#Create Virtual Environment.
virtualenv pgadmin4

This creates a folder called “pgadmin4“. We must enter it to get in to this folder.

cd pgadmin4

The next step will be to “activate” the virtual environment by running below statement.

#Activate virtual environment.
source bin/activate

Downloading and Installing pgAdmin

Now, we will install pgadmin on this machine. We can download latest version pgAdmin4-2.1 from this link. For this tutorial we will use the python package that is showing in below screenshot.

And finally we will proceed to install pgadmin using pip command as given below.

#Replace <path-where-file-is-located> with your patch followed by file name.
pip install <path-where-file-is-located>

We will be running below command in our case.

#Run below command to install pgadmin.
pip install /home/angelo/Descargas/pgadmin4-2.1-py2.py3-none-any.whl

With this pgAdmin is already installed but we are not finished yet. You need to create a local configuration and run it. Run below command to do this.

#Go to pgadmin4 folder
cd lib/python2.7/site-packages/pgadmin4

#Create config file
touch config_local.py

The “touch” command creates an empty file from the linux terminal, if the file exists it will change the date and time of the modification. In that file we can place the settings we want, if the file is left empty it will take the global settings of python.

We can now execute below command to create the credentials. Once you run below command, it will ask you to enter your email address and password. Those credentials will be the ones we use to access the application from the browser.

python lib/python2.7/site-packages/pgadmin4/pgAdmin4.pyc

Now we have created the credentials as well in above screenshot. At the end, we will be told that we must log in with our favorite browser to 127.0.0.1:5050 to log in and enter the main page of pgAdmin.

Let’s go to our browser and type 127.0.0.1:5050

We put our email address and the password we have previously entered. We can also select the language. Once we will be logged in using given credentials, we can see the main pgAdmin panel that is also showing in below screenshot.

We can test the application by adding a server. In this case it will be a local server. We must click on the “Add new Server” link given in between Quick Link section. We will get below screen to enter details about the server that we want to add.

The name we want to give to the connection is placed in the window. I called it “local.” We’ll leave the rest the same, if we want to.

In the connection tab, we will enter the connection parameters Host name, port, database, username, and password to add the server. You can see this in beow screenshot.

And with this we already have an added server and we can start working with postgreSQL. You can see the server is added in left side pane of pgAdmin panel. You can expand the plus sign to see the details like databases etc.

Conclusion

We have installed pgadmin 4 in debian 9 stretch to manage PostgreSQL databases. Data management is vital to system administration and specialized programs are required to keep data secure and properly structured. Complementing PostgreSQL we have pgAdmin that helps us, with a friendly graphical interface, to manage our databases, to make sentences and to monitor the service.

Installing both is one of the best ways to have and view databases in a way that is appropriate for our applications.

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Installing PostgreSQL in Debian GNU/LINUX is not a major problem, as it is available in the main repositories, but the version that comes with it is not the last one and does not allow us to have the latest updates and security patches that are necessary to ensure data protection.

Read below article if you want to install PostgreSQL administration and development tool pgAdmin on your Debian 9 stretch server.

• How to Install PgAdmin 4 on Debian 9 Stretch

New Features in PostgreSQL 10

PostgreSQL improves with each version, the changes are multiple both in administration and security level. Some important new features of PostgreSQL 10.1 are:

• Improved authentication process. Thanks to the new authentication system SCRAM-SHA-256.
• Many bug fixes for logical replication. Users can now fine-tune replicated data to multiple database clusters and will have the ability to perform zero-time activity updates to larger future versions of PostgreSQL.
• Declaratory partitioning of tables. This means that users no longer need to create triggers for routing data; it’s all handled by the system.
• Improved parallel query execution.
• Fix memory leak over the lifespan of a query when evaluating a set-returning function from the target list in a SELECT.

As has been said, there are many changes at the application level and you can consult them all here.

Install PostgreSQL 10.1 on Debian

Let’s get to work  to install PostgreSQL. We will start with Adding PostgreSQL Apt Repository.

The first thing we must do is to create a new file called pgdg.list in the following path: /etc/apt/sources. list.d/. To do this, we must be logged in as superuser. Run below command to connect using superuser.

--Connect using superuser
su

As you can see in the image, we must enter the password for root access. Then we invoke the nano editor and create the file in question.

nano /etc/apt/sources.list.d/pgdg.list

We further add the below line of code:

deb http://apt.postgresql.org/pub/repos/apt/stretch-pgdg main

Press Ctrl + x to save the changes. We say yes and with this we already have the repository added to our software sources.

The next step is import the repository signing key. After updating the package lists, doing this makes our package manager recognize the repository as a reliable one. Execute below commands in your terminal window to import the repository signing key.

--import the repository signing key
wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | apt-key add -

And to refresh the repository cache, just use the following command

--Update Package Lists
apt-get update 

We are now proceeding to install the latest version PostgreSQL 10.1 in our Debian 9 Stretch.  Write in Terminal:

--Install PostgreSQL Latest Version.
apt install postgresql-10

Above command will download and install the latest version of PostgreSQL on this Debian machine. Type Y and press enter to proceed with the installation. After downloading and installing the packages, we must initialize the postgreSQL service because if it is not running, it is not possible to access or connect with it. We can do it with the following command.

--Start PostgreSQL service.
systemctl start postgresql

We verify that we can make connection with PostgreSQL:

--Connect to PostgreSQL and Verify Installed PostgreSQL version.
su postgres -c psql postgres

And that’s it. That’s all.!!!!!!!!! We already have installed the latest version of this powerful database manager.

Now we can start working, for example, we can show the existing databases in a clean installation of PostgreSQL.

Conclusion

Debian is a large Linux distribution and is among the most popular in the world of system administrators. Known for its high stability and flexibility, but in its main repositories it has older versions of software and in many cases this is often a big problem. However, there are external repositories that facilitate the distribution of the latest versions of these programs.

PostgreSQL in the world of database has a very high reputation that makes it compete for the throne with other free alternatives such as Mysql or SQLite. Upgrading to the latest stable version guarantees us security patches and new features focused on speed, performance is very useful if we have a large database.

I hope you have learnt how to install PostgreSQL on Debian. Please follow our Facebook page and Twitter handle to get latest updates.

Read More:

• How to Install SQL Server 2017 on Ubuntu 16.04?
• Installing SQL Server 2017 on Red Hat Linux Server
• Installing SQL Server on Ubuntu in Offline Mode

The post How to Install PostgreSQL 10.1 in Debian 9 Stretch appeared first on Techyaz.com.