How To Install PHP on Debian 13

PHP 8.4 represents a significant milestone in web development, introducing groundbreaking features and performance improvements that revolutionize server-side scripting. This comprehensive guide provides detailed instructions for installing PHP 8.4 on Debian 13 “Trixie,” ensuring optimal configuration for both development and production environments.

What’s New in PHP 8.4

PHP 8.4 introduces several revolutionary features that enhance developer productivity and application performance. Property hooks provide cleaner getter and setter functionality, allowing developers to implement transparent property access without traditional method overhead. Asymmetric visibility offers enhanced access control, enabling different visibility levels for property reads and writes.

The updated DOM API now includes comprehensive HTML5 support, modernizing document manipulation capabilities. Performance improvements include enhanced Just-In-Time (JIT) compilation optimizations and significant memory usage reductions. Security enhancements feature AEGIS256 support in the Sodium extension for faster encryption operations.

However, PHP 8.4 also introduces breaking changes. Four extensions have moved from core to PECL: IMAP, Pspell, OCI8, and PDO_OCI. Implicitly nullable parameter declarations are now deprecated, and the E_STRICT constant faces deprecation. These changes require careful consideration when upgrading existing applications.

System Requirements and Prerequisites

Debian 13 “Trixie” provides the stable foundation required for PHP 8.4 installation. Minimum system requirements include 512MB RAM, though 2GB is recommended for production environments. The installation requires approximately 200MB of available disk space and root or sudo access privileges.

Essential system packages must be installed before proceeding with PHP 8.4 installation. These include apt-transport-https for secure repository connections, lsb-release for system identification, ca-certificates for SSL/TLS validation, and curl or wget for downloading repository keys. The gnupg2 package provides GPG key verification capabilities essential for repository security.

Network requirements include an active internet connection for package downloads and access to external repositories, specifically packages.sury.org. This repository, maintained by Ondřej Surý, provides trusted PHP builds for Debian systems.

Pre-Installation System Preparation

System preparation begins with updating existing packages to ensure compatibility and security. Execute the following command to update the package index and upgrade installed packages:

sudo apt update && sudo apt upgrade -y

This process ensures all system components remain current and compatible with PHP 8.4 installation.

Before installing PHP 8.4, create comprehensive system backups. Document existing PHP installations using the following command to list current PHP packages:

dpkg -l | grep php | tee packages.txt

This command generates a detailed list of installed PHP packages, saving the output to packages.txt for reference during installation.

Install essential dependencies required for repository management and secure package downloads:

sudo apt install -y apt-transport-https lsb-release ca-certificates curl gnupg2

Each package serves a specific purpose: apt-transport-https enables secure HTTPS repository connections, lsb-release provides system version identification, ca-certificates manages SSL certificate validation, curl handles file downloads, and gnupg2 manages GPG key verification.

Method 1: Installing PHP 8.4 Using Sury Repository (Recommended)

Adding the Sury PHP Repository

The Sury repository, maintained by Ondřej Surý (Debian’s official PHP package maintainer), provides the most reliable source for PHP 8.4 packages. This repository has established a proven track record within the Debian community and receives regular security updates.

Import the GPG key to verify package authenticity and security:

curl -fsSL https://packages.sury.org/php/apt.gpg | gpg --dearmor -o /etc/apt/trusted.gpg.d/sury-php.gpg

Alternatively, use wget for environments where curl is unavailable:

sudo wget -O /etc/apt/trusted.gpg.d/php.gpg https://packages.sury.org/php/apt.gpg

Add the repository to APT sources using the system’s codename:

echo "deb https://packages.sury.org/php/ $(lsb_release -sc) main" | sudo tee /etc/apt/sources.list.d/sury-php.list

Update the package index to recognize the new repository:

sudo apt update

Core PHP 8.4 Installation

Install the base PHP 8.4 package with command-line interface support:

sudo apt install -y php8.4

This command installs the core PHP 8.4 runtime and command-line interface. The installation automatically configures system paths and creates necessary directories.

Install the CLI interface separately if needed:

sudo apt install php8.4-cli

The CLI installation enables command-line PHP script execution and provides access to PHP’s interactive shell.

Verify the installation by checking the PHP version:

php -v

Expected output displays PHP 8.4.x version information, confirming successful installation.

Essential PHP Extensions Installation

Install commonly required PHP extensions using a comprehensive package list:

sudo apt install -y php8.4-cli php8.4-fpm php8.4-mysql php8.4-zip php8.4-xml php8.4-gd php8.4-curl php8.4-mbstring php8.4-bcmath php8.4-soap php8.4-readline php8.4-intl php8.4-common

For efficient bulk installation, use brace expansion:

sudo apt install php8.4-common php8.4-{bcmath,bz2,curl,gd,gmp,intl,mbstring,opcache,readline,xml,zip}

This method installs multiple extensions simultaneously, reducing installation time and ensuring consistency.

Discover additional available extensions using:

apt search php8.4

This command lists all available PHP 8.4 extensions in the repository, allowing customized installations based on specific requirements.

Method 2: Installing PHP-FPM for Web Server Integration

PHP-FPM Installation and Configuration

PHP-FPM (FastCGI Process Manager) provides superior performance compared to traditional Apache module installations. FPM offers better resource efficiency, improved process isolation, and enhanced security through separated process management.

Install PHP-FPM alongside the CLI interface:

sudo apt install php8.4-cli php8.4-fpm

The installation automatically enables and starts the PHP-FPM service. Verify service status using:

sudo systemctl status php8.4-fpm

Manage the PHP-FPM service with standard systemctl commands:

sudo systemctl start php8.4-fpm
sudo systemctl stop php8.4-fpm
sudo systemctl restart php8.4-fpm

Configuration files are located in /etc/php/8.4/fpm/php.ini for main settings and /etc/php/8.4/fpm/pool.d/www.conf for pool configuration.

Web Server Integration

For Apache integration, enable the PHP-FPM configuration:

sudo a2enconf php8.4-fpm
sudo systemctl restart apache2

This command activates the PHP-FPM configuration in Apache and restarts the web server to apply changes.

Nginx integration requires updating the fastcgi_pass directive in server blocks:

fastcgi_pass unix:/run/php/php8.4-fpm.sock;

Update Nginx configuration files to reference the PHP 8.4 FPM socket path.

Test web server integration by creating a PHP info file:

<?php
phpinfo();
?>

Save this content to /var/www/html/info.php and access it through a web browser to verify PHP-FPM functionality.

Version Management and Switching

The Sury repository enables multiple PHP version coexistence, allowing seamless switching between versions. Each PHP version installs in separate directories with unique binary paths: /usr/bin/php8.4, /usr/bin/php8.3, etc.

Configure version switching using update-alternatives:

sudo update-alternatives --config php

This interactive command presents available PHP versions for selection.

Set a specific version directly:

update-alternatives --set php /usr/bin/php8.4

For web server version switching with Apache modules:

sudo a2dismod php8.3
sudo a2enmod php8.4
sudo systemctl restart apache2

PHP-FPM version switching requires updating socket paths in web server configurations and restarting both FPM services and web servers.

Compare configuration files between versions:

diff /etc/php/8.3/cli/php.ini /etc/php/8.4/cli/php.ini

This command highlights configuration differences, facilitating migration planning.

Post-Installation Configuration and Optimization

Optimize PHP.ini settings for production environments by adjusting memory limits, execution timeouts, and file upload restrictions. Key configuration parameters include memory_limit, max_execution_time, upload_max_filesize, and post_max_size.

Configure OPcache for improved performance:

opcache.enable=1
opcache.memory_consumption=128
opcache.interned_strings_buffer=8
opcache.max_accelerated_files=4000
opcache.revalidate_freq=2
opcache.fast_shutdown=1

These settings optimize code caching and reduce script compilation overhead.

Set appropriate error reporting levels for different environments. Development environments benefit from comprehensive error reporting, while production systems require minimal error exposure for security.

Security hardening involves disabling dangerous functions in production:

disable_functions = exec,passthru,shell_exec,system,proc_open,popen

Configure open_basedir restrictions to limit file system access and set appropriate file permissions for PHP directories and files.

Development Tools and Extensions

Install Xdebug for development and debugging:

sudo apt install php8.4-xdebug

Configure Xdebug in /etc/php/8.4/mods-available/xdebug.ini for debugging, profiling, and code coverage analysis.

Install PCOV for code coverage analysis:

sudo apt install php8.4-pcov

PCOV provides efficient code coverage reporting for testing frameworks.

Install Composer for dependency management:

curl -sS https://getcomposer.org/installer | php
sudo mv composer.phar /usr/local/bin/composer

Verify Composer compatibility with PHP 8.4 using composer --version.

Install database extensions based on requirements:

• MySQL/MariaDB: php8.4-mysql
• PostgreSQL: php8.4-pgsql
• SQLite: php8.4-sqlite3

Framework-specific extensions enhance compatibility with popular PHP frameworks like Laravel and Symfony.

Troubleshooting Common Issues

Repository and GPG key issues often manifest as signature verification failures. Resolve these by reimporting GPG keys and verifying repository URLs. Connectivity problems may require proxy configuration or alternative download methods.

Extension loading problems typically result from missing dependencies or configuration conflicts. Check error logs in /var/log/php8.4-fpm.log for detailed diagnostics. Resolve dependency issues by installing required system libraries.

Web server integration issues frequently involve socket permission problems with PHP-FPM. Ensure proper ownership and permissions on socket files:

sudo chown www-data:www-data /run/php/php8.4-fpm.sock
sudo chmod 660 /run/php/php8.4-fpm.sock

Apache module conflicts require careful version management. Disable conflicting modules before enabling new versions to prevent configuration errors.

Performance and memory issues may indicate insufficient resource allocation. Monitor memory usage with ps aux | grep php and adjust memory_limit settings accordingly. Optimize for resource-constrained environments by disabling unnecessary extensions and reducing process counts.

Version compatibility problems arise when applications use deprecated features. Implement migration strategies for legacy applications by testing compatibility in development environments before production deployment.

Testing and Verification

Verify command-line functionality using:

php -v
php -m

These commands display version information and loaded modules. Test basic script execution with simple PHP files.

Create comprehensive web interface tests using phpinfo() pages. Verify extension loading and configuration settings through web browsers. Check error logs for any initialization warnings or errors.

Implement performance testing using basic benchmarking scripts. Monitor memory usage during typical application operations. Establish baseline performance metrics for future comparison.

Verify security configurations by testing file permission restrictions and disabled functions. Ensure error reporting settings appropriate for the deployment environment.

Maintenance and Updates

Maintain PHP 8.4 installations through regular security updates:

sudo apt update
sudo apt upgrade php8.4*

Monitor for new releases and security patches through official PHP channels and repository notifications.

Update extensions through the package manager to ensure compatibility and security. Handle PECL extension updates separately, as they follow independent release cycles.

Implement backup strategies before updates:

sudo cp /etc/php/8.4/fpm/php.ini /etc/php/8.4/fpm/php.ini.backup
sudo cp /etc/php/8.4/fpm/pool.d/www.conf /etc/php/8.4/fpm/pool.d/www.conf.backup

Document rollback procedures for problematic updates, including service restart commands and configuration restoration steps.

Set up log monitoring for PHP errors and performance issues. Implement log rotation to manage disk space usage effectively.

Best Practices and Security Considerations

Production environment setup requires comprehensive security hardening. Implement firewall rules restricting unnecessary port access. Configure fail2ban for intrusion detection and automated response to suspicious activities.

Regular maintenance tasks include log rotation, temporary file cleanup, and performance monitoring. Establish automated backup procedures for configuration files and application code.

Monitor PHP error logs continuously for security incidents and performance degradation. Set up alerting for critical errors and resource threshold violations.

Implement security patch management workflows ensuring timely application of updates. Test patches in staging environments before production deployment.

Congratulations! You have successfully installed PHP. Thanks for using this tutorial for installing the latest version of PHP programming language on Debian 13 “Trixie” system. For additional help or useful information, we recommend you check the official PHP website.