The default settings for the GRUB2 timeout menu selection during the system boot is 5 seconds. To change this value open /etc/default/grub grub default config file. The content of the file looks similar the the one shown below:
This is a companion discussion topic for the original entry at https://linuxconfig.org/update-grub2-menu-timeout-on-rhel-7-linux
elias
you rock, i’ve been struggling for a week to optimize centos startup time on vagrant
David Wade
you can also enter GRUB_TIMEOUT=-1 and the menu will come up and wait until you pick an option
Mon Kallus
Thanks for the “appear / disable GRUB 2 menu” . It helped a lot 