PHP

An easily integratable language for dynamic HTML with read/write file access possible on the server side.

Installation

As always, we’re assuming Debian + Nginx for this.

apt update
apt install php php-fpm

php-fpm should automatically enable it’s service. Verify via systemctl status php7.3-fpm.service

Setup

Check whether you want to use a TCP connection or a UNIX socket for php connections. The default and recommended way is TCP/IP.

TCP/IP

You can edit the IP and port of the connection in /etc/php/7.3/fpm/pool.d/www.conf The default is:

listen = 127.0.0.1:9000

Socket

For socket, use:

listen = run/php/php7.3-fpm.sock

Nginx

To enable nginx to talk to php add the following to your website config:

location ~ \.php${
    include snippets/fastcgi-php.conf
    fastcgi_pass 127.0.0.1:9000;
}

replace TCP/IP address with the appropriate socket file if that’s your preferred setup. Afterwards, since you’ve modified the nginx config, this of course requires a systemctl restart nginx. Tip: nginx -t let’s you verify your syntx without killing the running nginx instance, leading to a smoother switchover.

Create a file in the root dir for your website (so probably somwhere in /var/www/) ending in .php with the content:

<?php
    phpinfo();

And visit example.com/file.php to see whether it worked. You should get a screen with a lot of information about your php installation.

File writing permissions

Per default PHP is unable to read or write to your server drive. It is best for this to re-own any directories where php will be writing to to the user and group www-data. Thus a

chown -R www-data:www-data <dir>
chmod -R 744 <dir>

should be a good starting-off point. Files only need to have permissions of 644 of course so maybe change that as well.

Learning PHP

If you’re completely new to php w3schools’ course is probably a good starting point.