Remove excess Linux kernels (fedora, ubuntu)

After the Linxu system kernel is upgraded
Grub boot items display the boot options for the new and old kernels,

How to delete unnecessary boot items:

1. Find the kernel version installed in the system

Ubuntu command: $ dpkg -- get-selections | grep linux-image

Fedora command: $ su-c 'rpm-qa kernel'

2. Uninstall the old kernel version
Ubuntu command: $ sudo apt-get remove linux-image-2.6.35-22-generic # delete old Kernel
Fedora command: $ su-c 'yum remove kernel-2.6.40.6-0.fc15.i686
Restart and you will find that the old kernel startup option is no longer available!

After the Linxu system kernel is upgraded
Grub boot items display the boot options for the new and old kernels,

How to delete unnecessary boot items:

1. Find the kernel version installed in the system

Ubuntu command: $ dpkg -- get-selections | grep linux-image

Fedora command: $ su-c 'rpm-qa kernel'

2. Uninstall the old kernel version
Ubuntu command: $ sudo apt-get remove linux-image-2.6.35-22-generic # delete old Kernel
Fedora command: $ su-c 'yum remove kernel-2.6.40.6-0.fc15.i686
Restart and you will find that the old kernel startup option is no longer available!