How safe is it if I run the suggested command line. Is there a bug?
The following packages were automatically installed and are no longer required:
linux-headers-4.15.0-32 linux-headers-4.15.0-32-generic
linux-headers-4.15.0-33 linux-headers-4.15.0-33-generic
linux-headers-4.15.0-34 linux-headers-4.15.0-34-generic
linux-image-4.15.0-32-generic linux-image-4.15.0-33-generic
linux-image-4.15.0-34-generic linux-modules-4.15.0-32-generic
linux-modules-4.15.0-33-generic linux-modules-4.15.0-34-generic
linux-modules-extra-4.15.0-32-generic linux-modules-extra-4.15.0-33-generic
linux-modules-extra-4.15.0-34-generic
Use 'sudo apt autoremove' to remove them.
man apt-get
will quickly answer your question. – user535733 Nov 10 '18 at 16:47