[root@mypc ~]# egrep ^menuentry /etc/grub2.cfg | cut -f 2 -d \’
CentOS Linux (3.10.0-514.6.1.el7.x86_64) 7 (Core)
CentOS Linux (3.10.0-123.4.2.el7.x86_64) 7 (Core)
CentOS Linux, with Linux 3.10.0-123.el7.x86_64
CentOS Linux, with Linux 0-rescue-11264912be38456483e63dfd21d402f4

[root@mypc ~]# yum update |grep kernel-tools
—> Package kernel-tools.x86_64 0:3.10.0-514.6.1.el7 will be updated
—> Package kernel-tools.x86_64 0:3.10.0-514.21.1.el7 will be an update
—> Package kernel-tools-libs.x86_64 0:3.10.0-514.6.1.el7 will be updated
—> Package kernel-tools-libs.x86_64 0:3.10.0-514.21.1.el7 will be an update
kernel-tools             x86_64 3.10.0-514.21.1.el7        updates       4.0 M
kernel-tools-libs        x86_64 3.10.0-514.21.1.el7        updates       3.9 M

[root@mypc ~]# yum update -y

[root@mypc ~]# egrep ^menuentry /etc/grub2.cfg | cut -f 2 -d \’
CentOS Linux 7 Rescue d0faf3b598364cbfadf9ac867b7b6979 (3.10.0-514.21.1.el7.x86_64)
CentOS Linux (3.10.0-514.21.1.el7.x86_64) 7 (Core)
CentOS Linux (3.10.0-514.6.1.el7.x86_64) 7 (Core)
CentOS Linux (3.10.0-123.4.2.el7.x86_64) 7 (Core)
CentOS Linux, with Linux 3.10.0-123.el7.x86_64
CentOS Linux, with Linux 0-rescue-11264912be38456483e63dfd21d402f4