Test, validate and match regular expressions
This regex matches GRUB configuration lines for the GRUB_CMDLINE_LINUX directive, which specifies kernel boot parameters. It captures individual command line options (like 'quiet', 'splash', or 'root=/dev/sda1') separated by whitespace within the quotes. Useful for parsing and modifying GRUB configuration files, typically found at /etc/default/grub on Linux systems.