Install PHP-FPM and Common PHP Extensions on Ubuntu

PHP-FPM is the usual way to run PHP behind Nginx on Ubuntu. It gives you a long-running PHP process manager instead of starting PHP from scratch for every request.

This guide walks through installing PHP-FPM, adding common PHP extensions, detecting the installed PHP version, tuning php.ini, and restarting the right PHP-FPM service.

What the Script Does

The deployment script this article is based on:

• Installs PHP, PHP-FPM, PHP CLI, and common extensions.
• Detects the installed PHP major/minor version.
• Finds the matching PHP-FPM service name.
• Backs up the PHP-FPM and CLI php.ini files.
• Updates upload, post, memory, and execution-time limits.
• Enables and restarts PHP-FPM.

Install PHP and Extensions

Run:

sudo apt update

sudo apt install -y \
    php \
    php-fpm \
    php-cli \
    php-common \
    php-mysql \
    php-curl \
    php-gd \
    php-imagick \
    php-mbstring \
    php-xml \
    php-zip \
    php-intl \
    php-bcmath \
    php-redis \
    php-soap \
    php-readline \
    php-bz2 \
    php-gmp \
    php-ldap \
    php-sqlite3 \
    php-tidy \
    php-dev

Those extensions cover many common WordPress and PHP application needs, including MySQL, image handling, XML, ZIP files, Redis, SOAP, and multibyte strings.

Detect the PHP Version

Ubuntu package names include the PHP version in the FPM service name.

Detect it with:

PHP_VERSION="$(php -r 'echo PHP_MAJOR_VERSION.".".PHP_MINOR_VERSION;')"
PHP_FPM_SERVICE="php${PHP_VERSION}-fpm"
PHP_FPM_INI="/etc/php/${PHP_VERSION}/fpm/php.ini"
PHP_CLI_INI="/etc/php/${PHP_VERSION}/cli/php.ini"

echo "PHP version: ${PHP_VERSION}"
echo "PHP-FPM service: ${PHP_FPM_SERVICE}"
echo "PHP-FPM ini: ${PHP_FPM_INI}"
echo "PHP CLI ini: ${PHP_CLI_INI}"

Example output:

PHP version: 8.3
PHP-FPM service: php8.3-fpm
PHP-FPM ini: /etc/php/8.3/fpm/php.ini
PHP CLI ini: /etc/php/8.3/cli/php.ini

Back Up PHP Config Files

Create a backup folder:

sudo mkdir -p /opt/server-backups/php
timestamp="$(date +%Y%m%d%H%M%S)"

Back up both PHP-FPM and PHP CLI settings:

sudo cp "${PHP_FPM_INI}" "/opt/server-backups/php/php.ini.fpm.before.${timestamp}.bak"
sudo cp "${PHP_CLI_INI}" "/opt/server-backups/php/php.ini.cli.before.${timestamp}.bak"

Tune PHP-FPM

This example sets:

• upload_max_filesize = 64M
• post_max_size = 64M
• memory_limit = 256M
• max_execution_time = 300

Apply them to the PHP-FPM php.ini:

sudo sed -i "s/^upload_max_filesize = .*/upload_max_filesize = 64M/" "${PHP_FPM_INI}"
sudo sed -i "s/^post_max_size = .*/post_max_size = 64M/" "${PHP_FPM_INI}"
sudo sed -i "s/^memory_limit = .*/memory_limit = 256M/" "${PHP_FPM_INI}"
sudo sed -i "s/^max_execution_time = .*/max_execution_time = 300/" "${PHP_FPM_INI}"

For CLI PHP, a common setup is to keep memory aligned but allow long-running command-line jobs:

sudo sed -i "s/^memory_limit = .*/memory_limit = 256M/" "${PHP_CLI_INI}"
sudo sed -i "s/^max_execution_time = .*/max_execution_time = 0/" "${PHP_CLI_INI}"

Restart PHP-FPM

Enable and restart the detected service:

sudo systemctl enable "${PHP_FPM_SERVICE}"
sudo systemctl restart "${PHP_FPM_SERVICE}"
sudo systemctl is-active --quiet "${PHP_FPM_SERVICE}"

Save after-change backups:

sudo cp "${PHP_FPM_INI}" "/opt/server-backups/php/php.ini.fpm.after.${timestamp}.bak"
sudo cp "${PHP_CLI_INI}" "/opt/server-backups/php/php.ini.cli.after.${timestamp}.bak"

Troubleshooting

If PHP-FPM does not restart, check:

sudo systemctl status "${PHP_FPM_SERVICE}"
sudo journalctl -u "${PHP_FPM_SERVICE}" -xe

If Nginx returns 502 Bad Gateway, confirm that the Nginx site config points to the correct PHP-FPM socket for your PHP version.

Quick Reference

PHP_VERSION="$(php -r 'echo PHP_MAJOR_VERSION.".".PHP_MINOR_VERSION;')"
PHP_FPM_SERVICE="php${PHP_VERSION}-fpm"
sudo systemctl restart "${PHP_FPM_SERVICE}"
sudo systemctl status "${PHP_FPM_SERVICE}"

The important habit is to detect the installed PHP version instead of hard-coding one. That makes the script work across different Ubuntu releases.