Disabling PHP Short Open Tags

Short open tags (<? ?>) create compatibility issues with XML declarations and are considered poor practice. While they’re disabled by default in modern PHP versions, you may need to manage this setting when working with legacy code or specific server configurations.

Configuration Methods

Via php.ini

The primary way to control short open tags is through the php.ini configuration file:

short_open_tag = Off

Locate your active php.ini file:

php --ini

This outputs the configuration file path. Edit it directly:

sudo nano /etc/php/8.3/cli/php.ini

Then restart your web server:

sudo systemctl restart nginx
# or for Apache
sudo systemctl restart apache2

Via .htaccess (Apache only)

If you can’t modify php.ini, use .htaccess in your project root:

php_flag short_open_tag Off

This requires mod_php and won’t work with PHP-FPM configurations.

Via .user.ini (PHP-FPM)

For PHP-FPM setups, create a .user.ini file in your project root:

short_open_tag = Off

This takes effect within seconds (check user_ini.cache_ttl in php.ini if changes don’t apply immediately).

Via docker-compose or environment

In containerized environments, override settings at runtime:

RUN echo "short_open_tag = Off" >> /etc/php/8.3/fpm/php.ini

Verification

Check your current setting:

php -i | grep "short_open_tag"
# Output: short_open_tag => Off => Off

Or in a PHP script:

<?php
echo ini_get('short_open_tag') ? 'On' : 'Off';

Why This Matters

Modern frameworks (Laravel, Symfony, Drupal) and CMSs (WordPress) enforce the full <?php tag syntax. Short tags conflict with:

XML declarations (<?xml version="1.0"?>)
XHTML processing instructions
Server configurations where short tags are disabled

PHP 8.0+ disables short open tags by default. If you’re stuck supporting legacy code that uses them, use a code migration tool instead:

# Find all short tags in your codebase
grep -r "<?" --include="*.php" . | grep -v "<?php"

Then convert them systematically rather than relying on the setting being enabled across all environments.

Edge Cases

If you inherit a large codebase with short tags enabled everywhere, consider:

Automated replacement: Use sed to convert files

find . -name "*.php" -exec sed -i 's/<?\s/<?php /g' {} \;

Gradual migration: Keep short tags disabled in production while fixing code in development
AST-based tools: Use tools like PHP-Parser for safer refactoring of complex codebases

Always verify your application works after disabling short open tags—this surfaces incompatible code before it reaches production.

Additional Tips and Best Practices

When implementing the techniques described in this article, consider these best practices for production environments. Always test changes in a non-production environment first. Document your configuration changes so team members can understand what was modified and why.

Keep your system updated regularly to benefit from security patches and bug fixes. Use package managers rather than manual installations when possible, as they handle dependencies and updates automatically. For critical systems, maintain backups before making any significant changes.

Quick Verification

After applying the changes described above, verify that everything works as expected. Run the relevant commands to confirm the new configuration is active. Check system logs for any errors or warnings that might indicate problems. If something does not work as expected, review the steps carefully and consult the official documentation for your specific version.