I have installed two php versions. How to set default version.

 

To set the default PHP version when multiple versions are installed, you can use the update-alternatives command on Linux-based systems like Ubuntu or Debian. Here's how you can do it:

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Step 1: Check Installed PHP Versions

Run the following command to list the installed PHP versions:

php -v

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Step 2: Check Available PHP Alternatives

List all PHP alternatives managed by update-alternatives:

sudo update-alternatives --list php

You’ll see something like this:

/usr/bin/php7.4
/usr/bin/php8.1

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Step 3: Set Default PHP Version

To set a specific version as the default, use:

sudo update-alternatives --set php /usr/bin/php8.1

Replace /usr/bin/php8.1 with the path to the desired PHP version.

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Step 4: Use Interactive Selection (Optional)

If you want to select the version interactively:

sudo update-alternatives --config php

You’ll see a list of installed PHP versions:

There are 2 choices for the alternative php (providing /usr/bin/php).

  Selection    Path             Priority   Status
------------------------------------------------------------
* 1            /usr/bin/php7.4   74        auto mode
  2            /usr/bin/php8.1   81        manual mode

Press <enter> to keep the current choice[*], or type selection number:

Enter the number corresponding to your desired PHP version.

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Step 5: Verify the Change

Check the default PHP version again:

php -v

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Step 6: Configure PHP for Web Server (Optional)

If you are running a web server like Apache or Nginx, ensure the selected PHP version is active for it.

For Apache:

Disable the current PHP module and enable the desired one:

sudo a2dismod php7.4
sudo a2enmod php8.1
sudo systemctl restart apache2

For Nginx:

Ensure the fastcgi_pass directive in your Nginx configuration points to the correct PHP-FPM version, such as /run/php/php8.1-fpm.sock.

Restart PHP-FPM and Nginx:

sudo systemctl restart php8.1-fpm
sudo systemctl restart nginx

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Now, your default PHP version is set, and the web server should use it appropriately. Let me know if you face any issues!