grubby is a utility for manipulating bootloader-specific configuration files. You can use grubby also for changing the default boot entry, and for adding/removing arguments from a GRUB2 menu entry.

What is grubby used for?

grubby is a command line tool for updating and displaying information about the configuration files for various architecture specific bootloaders. It is primarily designed to be used from scripts which install new kernels and need to find information about the current boot environment.

What is Grub_enable_blscfg?

If it's not set at all, grub2-switch-to-blscfg adds a ' GRUB_ENABLE_BLSCFG=true ' setting to /etc/default/grub for you, and of course goes on to regenerate your grub.