How to Enable Essential PHP Extensions on a VPS with CentOS and cPanel

Most PHP applications, from WordPress to Laravel, need a handful of PHP extensions such as mbstring, intl, xml and pdo_mysql. On your own VPS you install them with the operating system's package manager. This guide covers the current Linux systems, what changed since CentOS reached end of life, and what to do if you are on shared hosting instead.

1. CentOS, cPanel and what changed

This article used to be written for CentOS with cPanel. Two things have changed:

• CentOS Linux has reached end of life and gets no more security updates. For a new server, choose a maintained distribution. AlmaLinux and Rocky Linux are the usual replacements if you want a CentOS-like system; Ubuntu LTS and Debian are the other common choices.
• Domain India VPS plans don't offer cPanel, because of its licence cost. You choose a Linux OS, and optionally one of the control panels listed on the VPS page, or run the server with no panel. If you need cPanel, our shared cPanel hosting includes it.

The commands below work on a plain VPS with no control panel. If you run your own licensed cPanel & WHM server elsewhere, see section 7.

2. The essential extensions

These are the extensions most frameworks and CMSs ask for. Several are built into PHP and are always present.

For what each extension does in more detail, see a list of PHP modules and their functions.

3. Check what is already loaded

Log in to your VPS over SSH and run:

php -v
php -m
php -m | grep -i -E 'intl|mbstring|pdo_mysql'

php -m shows the command-line PHP. Your website may run a different PHP version, or PHP-FPM with its own settings, so also check what the web server sees. Create a test file in your site's folder:

<?php
foreach (['intl', 'mbstring', 'pdo_mysql', 'gd', 'zip'] as $ext) {
    echo $ext . ': ' . (extension_loaded($ext) ? 'loaded' : 'missing') . "\n";
}

Open it in your browser, read the result, then delete the file. On your own server you can also use a phpinfo() page, but delete it straight away: it shows your whole configuration to anyone who finds it.

4. Install extensions on Ubuntu or Debian

Package names start with php-, such as php-intl, which installs the extension for the distribution's default PHP version. If you run a specific version, include it, as in php8.3-intl.

5. Install extensions on AlmaLinux or Rocky Linux

These systems use dnf, the successor to yum. The PHP version comes from the distribution; on some releases you can pick a newer one as a module stream, which you can list with sudo dnf module list php.

Some extensions, such as zip, redis or imagick, may not be in the base repositories. The EPEL repository, or a PHP repository your distribution's community recommends, usually has them. Prefer packages to compiling.

6. Extensions from PECL

When no package exists, PECL builds the extension from source:

sudo pecl install redis

You then need to load it: create a file such as /etc/php/8.3/mods-available/redis.ini on Ubuntu and Debian (then sudo phpenmod redis), or /etc/php.d/40-redis.ini on AlmaLinux and Rocky Linux, containing extension=redis. Restart PHP-FPM afterwards. PECL needs build tools and the PHP development headers (php-dev or php-devel) installed first, and a PECL build must be redone after a PHP version upgrade, which is one more reason to prefer packages.

7. If your server runs cPanel & WHM

On a server where you hold your own cPanel licence, PHP comes from EasyApache 4, and extensions are managed there rather than with plain dnf or apt package names:

• In WHM, open Software › EasyApache 4, click Customize on the current profile, open PHP Extensions, switch on the extensions you need for each PHP version, then Review and Provision.
• EasyApache package names include the PHP version, for example ea-php83-php-intl.
• Provisioning applies the change. If a site still doesn't see the extension, restart PHP-FPM as well as Apache, and check with the test file from section 3.

cPanel's own documentation is the reference for the EasyApache screens on your version.

8. On Domain India shared hosting

On shared hosting the PHP builds are shared by every account on the server, so you can't install, compile or load an extension yourself, and a php.ini or .user.ini line can't add one. The common extensions are already loaded on our cPanel and DirectAdmin servers. What you can do:

• Check what your site sees with the test file from section 3. phpinfo() is disabled on our cPanel servers, so use extension_loaded().
• Try another PHP version in your panel; see how to change the PHP version.
• Ask support. Open a ticket with the extension name, your domain and your PHP version, and we will tell you whether it can be provided.

Some functions are switched off for security on shared hosting even when their extension is loaded. See PHP disabled functions on shared hosting.

9. Where Domain India fits

If you need extensions shared hosting doesn't provide, your own PHP version or PECL modules, a VPS gives you root access to install them. Domain India VPS plans are self-managed by default: you choose the OS and look after the software and updates yourself.

Card prices are live list prices, excluding 18% GST.

Ready to set up your server? Compare VPS plans, or if you are on shared hosting, check your extensions and open a support ticket with the extension name and PHP version.