Version Switching

PHM installs multiple PHP versions side by side. There are two ways to switch between them.

Recommended: Symfony CLI + `.php-version`

The recommended approach is to use Symfony CLI with a .php-version file in your project root. This gives you automatic, per-project PHP version switching.

Setup

Install Symfony CLI via PHM:

phm install symfony

Create a .php-version file in your project root:

echo "8.5" > .php-version

Use symfony php instead of php:

symfony php -v
# PHP 8.5.4 (cli) ...

symfony composer install
symfony console cache:clear

Symfony CLI reads the .php-version file and automatically selects the correct PHP binary from PHM’s /opt/php/ directory.

Per-project workflow

project-a/
├── .php-version    # Contains: 8.4
├── composer.json
└── src/

project-b/
├── .php-version    # Contains: 8.5
├── composer.json
└── src/

cd project-a
symfony php -v    # PHP 8.4.19

cd ../project-b
symfony php -v    # PHP 8.5.4

Symfony local web server

Symfony CLI includes a built-in web server that also respects .php-version:

# Start the server (uses PHP version from .php-version)
symfony server:start -d

# Check which PHP version is being used
symfony server:status

# View logs
symfony server:log

# Stop the server
symfony server:stop

The Symfony server provides automatic HTTPS with locally-trusted certificates, HTTP/2 support, and handles .php-version seamlessly.

Alternative: `phm use`

For setting a system-wide default PHP version:

# Set PHP 8.5 as the global default
phm use 8.5

# Verify
php -v

This creates symlinks in /opt/php/bin/ pointing to the selected version. It affects all terminal sessions.

Comparison

Feature	Symfony CLI + `.php-version`	`phm use`
Scope	Per-project	Global
Switching	Automatic (reads file)	Manual command
Team-friendly	Yes (commit `.php-version`)	No
Web server	Built-in (with HTTPS)	Requires separate setup
Recommended	Yes	For simple setups