Install Wordpress on Ubuntu 16.04

Step 4: Download WordPress

Now that our server software is configured, we can download and set up WordPress. For security reasons in particular, it is always recommended to get the latest version of WordPress from their site.
Change into a writable directory and then download the compressed release by typing:

cd /tmp

curl -O https://wordpress.org/latest.tar.gz

Extract the compressed file to create the WordPress directory structure:

tar xzvf latest.tar.gz

We will be moving these files into our document root momentarily. Before we do, we can add a dummy .htaccess file and set its permissions so that this will be available for WordPress to use later.
Create the file and set the permissions by typing:

touch /tmp/wordpress/.htaccess

chmod 660 /tmp/wordpress/.htaccess

We'll also copy over the sample configuration file to the filename that WordPress actually reads:

cp /tmp/wordpress/wp-config-sample.php /tmp/wordpress/wp-config.php

We can also create the upgrade directory, so that WordPress won't run into permissions issues when trying to do this on its own following an update to its software:

mkdir /tmp/wordpress/wp-content/upgrade

Now, we can copy the entire contents of the directory into our document root. We are using the -a flag to make sure our permissions are maintained. We are using a dot at the end of our source directory to indicate that everything within the directory should be copied, including hidden files (like the .htaccess file we created):

sudo cp -a /tmp/wordpress/. /var/www/html

Step 5: Configure the WordPress Directory

Before we do the web-based WordPress setup, we need to adjust some items in our WordPress directory.

Adjusting the Ownership and Permissions

One of the big things we need to accomplish is setting up reasonable file permissions and ownership. We need to be able to write to these files as a regular user, and we need the web server to also be able to access and adjust certain files and directories in order to function correctly.
We'll start by assigning ownership over all of the files in our document root to our username. We will use sammy as our username in this guide, but you should change this to match whatever your sudo user is called. We will assign group ownership to the www-data group:

sudo chown -R sammy:www-data /var/www/html

Next, we will set the setgid bit on each of the directories within the document root. This causes new files created within these directories to inherit the group of the parent directory (which we just set to www-data) instead of the creating user's primary group. This just makes sure that whenever we create a file in the directory on the command line, the web server will still have group ownership over it.
We can set the setgid bit on every directory in our WordPress installation by typing:

sudo find /var/www/html -type d -exec chmod g+s {} \;

There are a few other fine-grained permissions we'll adjust. First, we'll give group write access to the wp-content directory so that the web interface can make theme and plugin changes:

sudo chmod g+w /var/www/html/wp-content

As part of this process, we will give the web server write access to all of the content in these two directories:

sudo chmod -R g+w /var/www/html/wp-content/themes

sudo chmod -R g+w /var/www/html/wp-content/plugins

This should be a reasonable permissions set to start with. Some plugins and procedures might require additional tweaks.

Setting up the WordPress Configuration File

Now, we need to make some changes to the main WordPress configuration file.
When we open the file, our first order of business will be to adjust some secret keys to provide some security for our installation. WordPress provides a secure generator for these values so that you do not have to try to come up with good values on your own. These are only used internally, so it won't hurt usability to have complex, secure values here.
To grab secure values from the WordPress secret key generator, type:

curl -s https://api.wordpress.org/secret-key/1.1/salt/

You will get back unique values that look something like this:
Warning! It is important that you request unique values each time. Do NOT copy the values shown below!

Output
define('AUTH_KEY',         '1jl/vqfs<XhdXoAPz9 DO NOT COPY THESE VALUES c_j{iwqD^<+c9.k<J@4H');
define('SECURE_AUTH_KEY',  'E2N-h2]Dcvp+aS/p7X DO NOT COPY THESE VALUES {Ka(f;rv?Pxf})CgLi-3');
define('LOGGED_IN_KEY',    'W(50,{W^,OPB%PB<JF DO NOT COPY THESE VALUES 2;y&,2m%3]R6DUth[;88');
define('NONCE_KEY',        'll,4UC)7ua+8<!4VM+ DO NOT COPY THESE VALUES #`DXF+[$atzM7 o^-C7g');
define('AUTH_SALT',        'koMrurzOA+|L_lG}kf DO NOT COPY THESE VALUES  07VC*Lj*lD&?3w!BT#-');
define('SECURE_AUTH_SALT', 'p32*p,]z%LZ+pAu:VY DO NOT COPY THESE VALUES C-?y+K0DK_+F|0h{!_xY');
define('LOGGED_IN_SALT',   'i^/G2W7!-1H2OQ+t$3 DO NOT COPY THESE VALUES t6**bRVFSD[Hi])-qS`|');
define('NONCE_SALT',       'Q6]U:K?j4L%Z]}h^q7 DO NOT COPY THESE VALUES 1% ^qUswWgn+6&xqHN&%');

These are configuration lines that we can paste directly in our configuration file to set secure keys. Copy the output you received now.
Now, open the WordPress configuration file:

nano /var/www/html/wp-config.php

Find the section that contains the dummy values for those settings. It will look something like this:

/var/www/html/wp-config.php

. . .

define('AUTH_KEY',         'put your unique phrase here');
define('SECURE_AUTH_KEY',  'put your unique phrase here');
define('LOGGED_IN_KEY',    'put your unique phrase here');
define('NONCE_KEY',        'put your unique phrase here');
define('AUTH_SALT',        'put your unique phrase here');
define('SECURE_AUTH_SALT', 'put your unique phrase here');
define('LOGGED_IN_SALT',   'put your unique phrase here');
define('NONCE_SALT',       'put your unique phrase here');

. . .

Delete those lines and paste in the values you copied from the command line:

/var/www/html/wp-config.php

. . .

define('AUTH_KEY',         'VALUES COPIED FROM THE COMMAND LINE');
define('SECURE_AUTH_KEY',  'VALUES COPIED FROM THE COMMAND LINE');
define('LOGGED_IN_KEY',    'VALUES COPIED FROM THE COMMAND LINE');
define('NONCE_KEY',        'VALUES COPIED FROM THE COMMAND LINE');
define('AUTH_SALT',        'VALUES COPIED FROM THE COMMAND LINE');
define('SECURE_AUTH_SALT', 'VALUES COPIED FROM THE COMMAND LINE');
define('LOGGED_IN_SALT',   'VALUES COPIED FROM THE COMMAND LINE');
define('NONCE_SALT',       'VALUES COPIED FROM THE COMMAND LINE');

. . .

Next, we need to modify some of the database connection settings at the beginning of the file. You need to adjust the database name, the database user, and the associated password that we configured within MySQL.
The other change we need to make is to set the method that WordPress should use to write to the filesystem. Since we've given the web server permission to write where it needs to, we can explicitly set the filesystem method to "direct". Failure to set this with our current settings would result in WordPress prompting for FTP credentials when we perform some actions.
This setting can be added below the database connection settings, or anywhere else in the file:

/var/www/html/wp-config.php

. . .

define('DB_NAME', 'wordpress');

/** MySQL database username */
define('DB_USER', 'wordpressuser');

/** MySQL database password */
define('DB_PASSWORD', 'password');

. . .

define('FS_METHOD', 'direct');

Save and close the file when you are finished.

Step 6: Complete the Installation Through the Web Interface

Now that the server configuration is complete, we can complete the installation through the web interface.
In your web browser, navigate to your server's domain name or public IP address:

http://server_domain_or_IP

Select the language you would like to use:

Next, you will come to the main setup page.
Select a name for your WordPress site and choose a username (it is recommended not to choose something like "admin" for security purposes). A strong password is generated automatically. Save this password or select an alternative strong password.
Enter your email address and select whether you want to discourage search engines from indexing your site:

When you click ahead, you will be taken to a page that prompts you to log in:

Once you log in, you will be taken to the WordPress administration dashboard:

Upgrading WordPress

As WordPress upgrades become available, you will be unable in install them through the interface with the current permissions.
The permissions we selected here are meant to provide a good balance between security and usability for the 99% of times between upgrading. However, they are a bit too restrictive for the software to automatically apply updates.
When an update becomes available, log back into your server as your sudo user. Temporarily give the web server process access to the whole document root:

sudo chown -R www-data /var/www/html

Now, go back the WordPress administration panel and apply the update.
When you are finished, lock the permissions down again for security:

sudo chown -R sammy /var/www/html

This should only be necessary when applying upgrades to WordPress itself.