How to Install CentOS 7

Prerequisites

  • Recommended minimum of 10GB of free disk space
  • CentOS 7 ISO install file

Follow the Steps to Install CentOS 7
If you are only looking to update or upgrade CentOS, see How to Upgrade or Update CentOS.

Step 1: Download CentOS 7

To download the official and up-to-date CentOS 7 ISO file, navigate to https://www.centos.org/download/.
Our recommendation for non-enterprise environments is to download the DVD ISO option, which includes the GUI. We recommend the Minimal ISO option only for production enterprise environments.

Select DVD ISO option for CentOS 7 installation.

Step 2: Create Bootable USB or DVD

Now that you have downloaded the ISO image, you can create a bootable USB, burn it on a DVD or load the image on a VM.
Several applications can help you create a bootable USB. We recommend using Etcher. Download the application for your system (Windows, macOS or Linux), install and run.

etcher running on a drive

The setup is intuitive and easy:

  1. Select the CentOS 7 ISO image.
  2. Insert the USB flash.
  3. Find the USB and select it in the Select drive step.
  4. Click Flash.

Step 3: Boot the CentOS ISO File

Upon booting the CentOS 7 ISO file, you can begin the installation process. To do so, select Install CentOS 7. That will start the installer’s graphical interface.
Read More

How to Set or Change a Hostname in CentOS 7

Prerequisites

  • Server running CentOS 7
  • Access to a user account with root privileges
  • Terminal window (Menu > Applications > Utilities > Terminal)
  • A text editor, like Vim

How to Change Centos Hostname

Step 1: Check Existing Hostname

Before you start, it is advised to check what your current hostname is. Type the following command in the console to find out:

hostnamectl

The output should return the static hostname, as well as a list of other information about your network configuration and operating system.

check static hostname on centos

Step 2: Set a New Static Hostname

As CentOS 7 only allows Fully Qualified Domain Names (FQDNs), double-check the hostname you plan to use.
Acceptable values include:

  • Lower-case letters a to z
  • Numbers 0 to 9
  • Periods and hyphens
  • Hostnames must be between 2 and 63 characters
  • Hostnames must start and end with a number or letter

Type in the following command in the terminal:

hostnamectl set-hostname my.new-hostname.server

Note: Make sure to replace my.new-hostname.server with your chosen hostname.


Step 3: Check the Hostname

Next, verify the hostname by using the following command again:

hostnamectl

The console should display the new hostname.

Step 4: Edit the /etc/hosts File

Start by opening the hosts file by typing:

sudo vim /etc/hosts

In the text editor, look for the line that begins with 127.0.0.1 (the IP address that refers to the system you are working on). It should read:

127.0.0.1  localhost localhost.localdomain localhost 4 localhost4.localdomain4 old.hostname

Change the entry old.hostname to my.new-hostname.server – and spell it the same as in Step 2.
Save the file and exit.

Step 5: Reboot and Check CentOS 7 machine hostname

Restart your system. Open a console window, and run:

hostnamectl

It should display your new hostname.
You can also use your text editor to open and verify your /etc/hostsfile. It should still have your new hostname listed.

Step 6 (Optional): Using a Pretty Hostname

To use a “pretty” hostname type the following command:

hostnamectl set-hostname “My Boss’s Hostname”

Make sure you have the quotation marks.
Once that completes, check the hostname:

hostnamectl status

The console should return a list of information. Check the Static hostname and Pretty hostname lines – they should look like this:

Static hostname:  mybossshostname
Pretty hostname:  My Boss’s Hostname

By putting the hostname in quotes, you’re telling the system to use the complex characters inside the quotes as a pretty hostname.
This enables you to avoid character restrictions for static hostnames.

using a pretty name on centos

But you still need a FQDN hostname for the machine to understand. Fortunately, CentOS is smart enough to remove or change any unacceptable characters and render the static hostname automatically.

Step 7 (Optional): Setting a Transient Hostname

Fist, open the console and type the following:

sudo hostnamectl –transient set-hostname temporary.hostname

You can check the hostname in the same way you did earlier, with the hostnamectl or hostnamectl status command.
This change will last until you reboot the machine.
You can use this command with any type of hostname (Static, Pretty, or Transient) as an option with the double-hyphen.
Just use the double-hyphen to indicate what you want:

sudo hostnamectl --prettyset-hostname “Pretty Hostname”

or

sudo hostnamectl --staticset-hostname temporary.hostname

How to Install WordPress On CentOS 7

Step 1) Preflight Check:

This article assumes you have CentOS 7 installed and are logged into your server as the root user. We are also using the most recent version of WordPress for this install. This article also assumes you have already installed LAMP (Linux, Apache, MySQL, PHP) on your server and your PHP is updated to the latest version. You will also need to know your root mysql password so you can log into mysql as root.
Need help to install LAMP? Click this link!
mysql
 
If the above command isn’t working for you, then you may not be logged in as root user. In that case, you can run the following instead.
mysql -u root -p
 
Keep in mind that you will be prompted for the password you set earlier as root when you installed MySQL so you will need to have that handy. If you do not have your root password, you will have to reset it. If you need help with that, check out this article here and scroll down to the method via “Reset using command line“. Once you do gain access, you can safely move to step 2!
 
A successful login should look something like this:
login
 
 
 
 
 

Note:
To exit mysql at any time simply type: exit

exit
 

Step 2) Create a database

Hooray! We successfully logged in. Now we can create a database with the following command. You can call it whatever you would like, but for this article, we are calling it WordPress.
CREATE DATABASE wordpress;

Note:
While it’s easier to copy and paste directly in the command line. You should know that every mysql command will require a ;  (colon) at the end of every statement in case you are getting an error.

Once our database is created, you need to create a user for that database. Once again I am using a very simple username, and password so feel free to make yours more secure. Do remember your username and password as we will need it later in this article. Type the following command.
CREATE USER [email protected] IDENTIFIED BY 'password';
At this point, we have created a database user however, we still need to give that user permissions to access the database. We can add those permissions with the following command:
GRANT ALL PRIVILEGES ON wordpress.* TO [email protected] IDENTIFIED BY 'password';
Replace anything in red with your database name, user, and password. Also, note that the password is contained in single quotes followed by a colon;

Note:
Remember your username and password you use in this step as will be needed later.

Now we want to flush MySQL so that it is made aware of those changes.
FLUSH PRIVILEGES;
 
and finally, exit MySQL
exit

 

Step 3) Install WordPress

 
cd ~
wget http://wordpress.org/latest.tar.gz

 

Note:
if you do not have wget yet you can download it with yum using the following:

 
yum install wget
 
Now, let’s  unzip that tar file
tar -xzvf latest.tar.gz
 
That should create a file named WordPress in our home directory. Next, we want to move that file and its contents to our public_html folder, so it can serve up the content for our website. We want to keep the same file permission, so we use the following rsync command.
sudo rsync -avP ~/wordpress/ /var/www/html/
For WordPress to be able to upload files, we need to create an uploads directory. Go ahead and use the following:
mkdir /var/www/html/wp-content/uploads
 
Lastly, update the Apache permissions for new WordPress files
sudo chown -R apache:apache /var/www/html/*

Step 4) Configuring WordPress

Next, we have to update the wp-config.php file in WordPress for it to connect to the database successfully. So let’s go to the html folder where your WordPress install is located.
cd /var/www/html
Create a wp-config.php file by copying the sample file WordPress has provided.
cp wp-config-sample.php wp-config.php
Now, we need to edit the new wp-config.php file with the correct database information we created in Step 1.
I used vim to make that change, but you can use any editor you are comfortable with.
vim  wp-config.php
Next, we need to add info into the following fields of the databaseuser, and password we created in Step 1.
Old Settings:
// ** MySQL settings - You can get this info from your web host ** //
/** The name of the database for WordPress */
define( 'DB_NAME', 'database_name_here' );
/** MySQL database username */
define( 'DB_USER', 'username_here' );
/** MySQL database password */
define( 'DB_PASSWORD', 'password_here' );


New Settings:

// ** MySQL settings - You can get this info from your web host ** //
/** The name of the database for WordPress */
define( 'DB_NAME', 'wordpress' );
/** MySQL database username */
define( 'DB_USER', 'adminuser' );
/** MySQL database password */
define( 'DB_PASSWORD', 'password' );

Once you have made those changes, go ahead and save the file using the :wq command in Vim.
 

Step 5) Setup through wp-admin and verification

Now, let’s verify that your WordPress install is working. You should see something like the following on your server page. Replace server_domain_name_or_IP with your server name or IP.
http://server_domain_name_or_IP/wp-admin
install
 
If this is what you see then congrats!!! You have successfully installed WordPress on your Centos server, and you can close this article!
 
I have also listed a couple of common issues you might encounter in the sections below. Keep in mind that we cannot list every possible issue but, we have listed what we believe are the most common problems you may run into.
 

 

Database Error Establishing a Connection

If you are getting an Error about establishing a Database connection, verify that your wp-config.php file has the correct userpassword and database name. There should be no spaces between the single quotes! This error usually means you have something going on in the wp-config.php file so be sure to check your syntax.
// ** MySQL settings - You can get this info from your web host ** //
/** The name of the database for WordPress */
define( 'DB_NAME', 'database_name_here' );
/** MySQL database username */
define( 'DB_USER', 'username_here' );
/** MySQL database password */
define( 'DB_PASSWORD', 'password_here' );


Troubleshooting and Verifying php

The most common issue with php is, that it may not be fully up to date in order for it to work with the newer versions of WordPress. Usually, you will get the error “WordPress requires at least php version…
In this next step, we will verify the php version is at least PHP 7.1, by creating a phpinfo.php page. However, it is always preferable to have the most up to date version of PHP, which at the time of this article is PHP 7.2, especially for security reasons.
To create a phpinfo page go to your /var/www/html and create a file called phpinfo.php.
touch phpinfo.php
chmod 644 phpinfo.php

 
and then, let’s add the following code:
<?php
// Show all information, defaults to INFO_ALL
phpinfo();
?>

Then, go to http://server_domain-name_or_IP/phpinfo.php
phpinfo page
And you should see something like this if your php is set up successfully.
 
If for some reason your php is out of date, you may have to update yum’s config file to do so.
 
First, double-check you have to correct yum packages with the following command
 
yum install http://rpms.remirepo.net/enterprise/remi-release-7.rpm
To enable php 7.2, we need to enable the php 7.2 remi repo. At the time of the release of this article, we are using php 7.2. So, in going forward, when they release php 7.4 or php 7.5, you would edit the corresponding file.
 
These should be located in your /etc/yum.repos.d folder. Open the file with vim, and change the enabled field to a 1, and then save the file using vim’s :wq command
[remi-php72]
name=Remi's PHP 7.2 RPM repository for Enterprise Linux 7 - $basearch
#baseurl=http://rpms.remirepo.net/enterprise/7/php72/$basearch/
#mirrorlist=https://rpms.remirepo.net/enterprise/7/php72/httpsmirror
mirrorlist=http://cdn.remirepo.net/enterprise/7/php72/mirror
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-remi

Update yum
yum update
Now, check for the php version of the php-fpm packages that should be on the server, under the field Version:
 
The output should look similar to this
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: centos.myfahim.com
* epel: mirror.ehost.vn
* extras: centos.myfahim.com
* remi-php72: mirrors.thzhost.com
* remi-safe: mirrors.thzhost.com
* updates: centos.myfahim.com
remi-php72 | 2.9 kB 00:00:00
remi-php72/primary_db | 195 kB 00:00:08
Available Packages
Name : php
Arch : x86_64
Version : 7.2.8
Release : 1.el7.remi
Size : 3.2 M
Repo : remi-php72
Summary : ........

Next, install, enable and then start php fpm with the following commands:
yum install php-fpm php-gd php-pdo php-mbstring php-pear -y
systemctl enable php-fpm
systemctl start php-fpm

Don’t forget to restart apache, and/or php, if changes where made.
 
If using Apache:
service httpd restart
If using Nginx:
service nginx restart
 
Once completed, your phpinfo.php page should show you using php 7.2 or later. If you are using Nginx, you may have to verify that it knows to how to send php requests to php-fpm. If you have an issue, double-check your nginx.conf for errors or misconfiguration problems.
If your php is working and up to date, check your web server settings.
 

Troubleshooting and verifying your web server

You should also check that your Apache or Nginx and ports configured correctly. You should be able to go here
http://server_domain_name_or_IP
and see something similar to this if apache is set up successfully.
testing123
Alternatively, if your using Nginx, something similar to this will appear
 
Lastly, don’t forget to restart your webserver any time you make changes.
 
If you are not getting one of these success pages, double check your configuration files in your Apache or Nginx settings. Also, you can check to see if you are listening to the proper ports.

How To Install the LAMP Stack on CentOS 7

Pre-flight Checks

To find out which Linux distribution you are running, use this command:
cat /etc/redhat-release
It’s now time to verify that our yum environment is clean and up to date, we’ll do this by cleaning all of the yum cache, and update yum using:
yum clean all
yum update

Installing LAMP

Now that we know what environment we’re working in let’s get started on installing the LAMP stack on CentOS 7:

L – Linux

The first part of the stack is Linux. This is your operating system and since it is already installed there no need to worry about installing it or make any modifications. Installing CentOS 7 is easy to download and install using the image files that are provided from centos.org. CentOS has a helpful installation guide if you need to reference it for additional installation instructions.

A – Apache

Apache is the next piece of the LAMP stack. Apache is the webserver software that is responsible for serving the content to your web browser from the server. It takes the requests that it receives and sends back the HTML code for your browser to interpret.
Install Apache using Yum:
yum -y install httpd
Open ports in the FW:
firewall-cmd --permanent --add-service=http -add-service=https
firewall-cmd --reload
Start and enable apache to run when the server starts:
systemctl start httpd
systemctl enable httpd

Default Apache installation locations:

Some important server locations to remember for Apache are listed below. These are out-of-the-box defaults and can be changed as you see fit:
httpd binary: /sbin/httpd
Apache configuration file: /etc/httpd/conf/httpd.conf
Website files: /var/www/html/
Apache logs: /var/log/httpd/

M – MySQL/MariaDB

MySQL and MariaDB are what handle your website’s database. In most of today’s websites, data is not stored in flat or static files. Instead, the base of the site is coded in PHP which can pull information from your website’s database to deliver more dynamic content. MySQL and MariaDB are popular database servers that help house that information. MariaDB is becoming more widely used, so we’ll use for installation. Both are very similar in setting up and configuring.
Install MariaDB:
yum -y install mariadb-server
systemctl start mariadb
Although securing mysql is optional, it is strongly recommended:
mysql_secure_installation
**Run through the steps on screen to secure your Mysql/MariaDB environment
Enable MariaDB to start when the server starts:
systemctl enable mariadb

Default installation locations:

Some important server locations to remember for MySQL/MariaDB are listed below. These are out-of-the-box defaults and can be changed as you see fit:
MariaDB binary: /bin/mysql
MariaDB Configuration file: /etc/my.cnf
Database location: /var/lib/mysql
MariaDB logs: /var/log/mariadb/mariadb.log

P – PHP

Most websites that exist today are built using PHP coding. PHP provides the programmer with more options for dynamic content compared to flat html code. Several PHP versions are available for use depending on what PHP version the website was built in. We’ll install the latest version of PHP.
In order to install the latest PHP version, we first need to install CentOS’s Software Collection repository (SCL):
yum -y install centos-release-scl.noarch
We’ll now have access to install PHP 7.2 :
yum -y install rh-php72
Now we’ll fix the symbolic link for the binary:
ln -s /opt/rh/rh-php72/root/usr/bin/php /usr/bin/php
Install the updated PHP Module for Mysql/MariaDB:
yum -y install rh-php72-php-mysqlnd
Restart apache to work with the newly installed PHP:
systemctl restart httpd