$ sudo linux-purge --list --keep=2 [linux-purge] WARNING: Using whiptail, if needed, because dialog is not installed. [linux-purge] ERROR: There are no meta-kernels so can not decide which kernels to keep.
$ sudo linux-purge --list --keep=2
[linux-purge] WARNING: Using whiptail, if needed, because dialog is not
installed.
[linux-purge] ERROR: There are no meta-kernels so can not decide which kernels
to keep.