Here is a step-by-step tutorial in English on how to enable OPcache.

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### Step 1: Install the OPcache PHP Extension

First, you need to install the OPcache module for your specific PHP version. The package name is typically `php-opcache`, but it's a virtual package. You must specify the exact version.

1.  **Check your PHP version:**
    `php -v`

2.  **Install the correct package:**
    Replace `<version>` with your PHP version (e.g., `8.3`, `8.4`).
    `sudo apt install php<version>-opcache`

This command installs the extension for both the CLI (Command-Line Interface) and PHP-FPM/Apache.

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### Step 2: Configure `php.ini`

Now, you need to enable and configure OPcache in your PHP configuration file. The file's location depends on your web server.

1.  **Find your `php.ini` file:**

      * **For Nginx/PHP-FPM:** `/etc/php/<version>/fpm/php.ini`
      * **For Apache:** `/etc/php/<version>/apache2/php.ini`

2.  **Edit the file:**
    Open the file using a text editor like `nano`.
    `sudo nano /etc/php/<version>/fpm/php.ini`

3.  **Add/Edit the `[opcache]` section:**
    Add or find the `[opcache]` section and ensure the following lines are present and uncommented (remove the `;` if it's there).

    ```ini
    [opcache]
    opcache.enable=1
    opcache.memory_consumption=512
    opcache.max_accelerated_files=20000
    opcache.revalidate_freq=60
    ```

      * `opcache.enable=1`: This enables OPcache for your web server.
      * `opcache.memory_consumption`: Adjust this value based on your server's RAM and website size. For a 24 GB server and a large site, `512` is a good starting point.
      * `opcache.max_accelerated_files`: Adjust this based on the number of PHP files in your project. A value of `20000` or higher is recommended for large websites.
      * `opcache.revalidate_freq`: This tells OPcache how often (in seconds) to check for file updates. `60` is a good value for a production environment.

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### Step 3: Restart Your Web Server

After saving the `php.ini` file, you must restart your web server for the changes to take effect. The command depends on your setup.

  * **For Nginx (with PHP-FPM):**
    `sudo systemctl restart php<version>-fpm`

  * **For Apache (with mod\_php):**
    `sudo systemctl restart apache2`

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### Step 4: Verify that OPcache is Active

To confirm that OPcache is working, create a PHP info file in your web root.

1.  **Create a file named `info.php`:**

    ```php
    <?php
    phpinfo();
    ?>
    ```

2.  **View the file in your browser:**
    Navigate to `http://your_domain.com/info.php`.

3.  **Check the OPcache section:**
    Search for **"Zend OPcache"**. The "Opcode Caching" status should be **"Up and Running"**.  You will also see the configuration settings you just applied.