Is it not possible to install the mysql2 gem on Ubuntu 21 with Ruby 2.7.6?

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It is definitely possible to install the mysql2 gem on Ubuntu 21 with Ruby 2.7.6. Here are the steps:

1. Update the Ubuntu package manager:

   sudo apt-get update
   

2. Install the MySQL client library:

   sudo apt-get install libmysqlclient-dev
   

3. Install the mysql2 gem:

   gem install mysql2
   

If you encounter any issues during the installation process, you may need to install additional dependencies or troubleshoot your Ruby and MySQL installations.