CentOS deletes the old (kernel) kernel

When CentOS updates the kernel, many startup items will be added during startup. we can delete the old kernel and keep the latest kernel so that some disk space (/boot) can be released ). (1) view the installed kernel command: rpm-qkernel display result: kernel-2.6.32-279.14.1.el6.i686kernel-2.6.32-279.el6.x CentOS Kernel updated, will lead to a lot of startup items, we can delete the old kernel, keep the latest kernel to release some disk space (/boot ).
(1) view installed kernels
Command: rpm-q kernel
Show Results: kernel-2.6.32-279.14.1.el6.i686
Kernel-2.6.32-279.el6.x86_64
Kernel-2.6.32-358.6.1.el6.x86_64
(2) method 1 of deleting the old kernel:
Install yum-utls: yum install-y yum-utils
Set how many old kernels you want to retain, for example, I want to keep two: sudo package-cleanup -- oldkernels -- count = 2
Run rpm-q kernel again to view kernel information, with only the latest two: kernel-2.6.32-279.el6.x86_64
Kernel-2.6.32-358.6.1.el6.x86_64 Method 2: rpm-e kernel-2.6.32-279.14.1.el6.i686
(3) set the number of permanent kernel installations. I have set two
Sudo vi/etc/yum. conf
Set installonly_limit = 2
(4) restart and you will only see two kernel boot items.