How to use the command 'phpdismod' (with examples)

The phpdismod command is a powerful tool used to manage PHP extensions on Debian-based operating systems. It allows you to disable PHP extensions, which can be crucial for maintaining a secure and efficient server environment. By selectively disabling certain PHP extensions, administrators can optimize server performance, enhance security, and ensure compatibility with specific applications or configurations. The command provides flexibility in handling different versions of PHP and varying server application programming interfaces (SAPIs).

Use case 1: Disable the JSON extension for every SAPI of every PHP version

Code:

sudo phpdismod json

Motivation:

This command is used when you want to quickly disable the JSON extension across all versions and SAPIs of PHP installed on your system. JSON (JavaScript Object Notation) is a commonly used data format, and the extension is frequently enabled by default. However, for security reasons or compatibility issues, you might need to disable this extension globally. For instance, if an application on your server has its own JSON parsing mechanism or if an extension conflict occurs, disabling the JSON extension system-wide can prevent disruptive behavior.

Explanation:

• sudo: This prefix is used to execute the command with superuser privileges, which is necessary when making system-level changes like modifying PHP configurations.
• phpdismod: This is the command used to disable PHP extensions.
• json: This is the name of the PHP extension that you want to disable. By specifying just the extension name, you direct the command to disable it across all installed PHP versions and SAPIs.

Example Output:

Upon running this command, you might not see any immediate output to the terminal. However, to verify the change, you can list PHP extensions for any version using, for example, php -m for any PHP version, and confirm that the json extension no longer appears.

Use case 2: Disable the JSON extension for PHP 7.3 with the cli SAPI

Code:

sudo phpdismod -v 7.3 -s cli json

Motivation:

This use case focuses on a more granular approach where the JSON extension is only disabled for PHP version 7.3 and only when PHP is executed via the command line interface (CLI). Such precision is essential when different applications on the same server may rely on different versions of PHP or work with different environments like CLI or Apache module. By targeting a specific version and SAPI, you ensure that only the relevant contexts are affected, reducing the risk of inadvertently disrupting web-facing applications or APIs that may rely on JSON extension in other PHP versions or environments.

Explanation:

• sudo: Again, this prefix escalates privileges to allow for system-level changes.
• phpdismod: The command responsible for disabling PHP extensions.
• -v 7.3: This argument specifies the PHP version for which the extension should be disabled. In this case, it’s version 7.3, allowing for targeted changes that don’t affect other versions.
• -s cli: This option sets the specific SAPI, which is the CLI in this scenario. The CLI SAPI is used for command-line scripts, so this change will not impact web applications running under other SAPIs like Apache or FastCGI.
• json: The name of the extension being disabled.

Example Output:

This command, like the previous one, typically doesn’t provide direct terminal feedback. To verify the effect, you can run php7.3 -m on the CLI and check that the json module is no longer listed in the output.

Conclusion:

The phpdismod command is an essential tool for managing PHP extensions on Debian-based systems. By using the command’s flexible options, administrators can precisely control the PHP environment, enhancing server performance and security. Whether disabling extensions across all PHP versions or targeting specific SAPIs and versions, phpdismod provides the granularity needed for effective server management.