1. grub2-editenv list
saved_entry=CentOS Linux (3.10.0-1160.el7.x86_64) 7 (Core)
这个命令查询出当前启动的内核版本。
2.grep ^menu /boot/grub2/grub.cfg
menuentry 'CentOS Linux (3.10.0-1160.el7.x86_64) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-1160.el7.x86_64-advanced-26a5fd4c-b8a4-4010-b378-b82e841ac433' {
menuentry 'CentOS Linux (0-rescue-46718494b30f470a96ba54dcc33dcfee) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-0-rescue-46718494b30f470a96ba54dcc33dcfee-advanced-26a5fd4c-b8a4-4010-b378-b82e841ac433' {
3.设定为第一个内核的命令
grub2-set-default 0
