Eventually, the boot sector space filled with the downloaded images which creates system issues. Following commands are useful in identifying old images in the /boot partition and purge them from the system.
Initially, use df -h command and get the information about the space of the partitions
#df -h
Filesystem Size Used Avail Use% Mounted on
udev 3.9G 0 3.9G 0% /dev
tmpfs 787M 9.4M 778M 2% /run
/dev/mapper/ubuntu--vg-root 909G 255G 608G 30% /
tmpfs 3.9G 348K 3.9G 1% /dev/shm
tmpfs 5.0M 4.0K 5.0M 1% /run/lock
tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
/dev/sda1 472M 468M 0 100% /boot
tmpfs 787M 64K 787M 1% /run/user/1000
This provides the space availability of each partition and clearly shows the /boot partition is fully filled.
Go to /boot and type following command to identify the installed images in the system
#cd /boot
#dpkg -l linux-image-\* | grep ^ii
ii linux-image-4.4.0-108-generic 4.4.0-108.131 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP
ii linux-image-4.4.0-109-generic 4.4.0-109.132 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP
ii linux-image-4.4.0-112-generic 4.4.0-112.135 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP
ii linux-image-4.4.0-116-generic 4.4.0-116.140 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP
ii linux-image-4.4.0-121-generic 4.4.0-121.145 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP
ii linux-image-4.4.0-127-generic 4.4.0-127.153 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP
ii linux-image-4.4.0-128-generic 4.4.0-128.154 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP
ii linux-image-extra-4.4.0-108-generic 4.4.0-108.131 amd64 Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
ii linux-image-extra-4.4.0-109-generic 4.4.0-109.132 amd64 Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
ii linux-image-extra-4.4.0-112-generic 4.4.0-112.135 amd64 Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
ii linux-image-extra-4.4.0-116-generic 4.4.0-116.140 amd64 Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
ii linux-image-extra-4.4.0-121-generic 4.4.0-121.145 amd64 Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
ii linux-image-extra-4.4.0-127-generic 4.4.0-127.153 amd64 Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
Use uname command to check the current image version of the system
# uname -a
Linux chamara-X556UAK 4.4.0-128-generic #154-Ubuntu SMP Fri May 25 14:15:18 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
Use apt-get purge command to remove older versions of the images.
# sudo apt-get purge linux-image-4.4.0-108
Reading package lists... Done
Building dependency tree
Reading state information... Done
...
..
..
..
done
Purging configuration files for linux-image-4.4.0-108-generic (4.4.0-108.131) ...
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 4.4.0-108-generic /boot/vmlinuz-4.4.0-108-generic
run-parts: executing /etc/kernel/postrm.d/zz-update-grub 4.4.0-108-generic /boot/vmlinuz-4.4.0-108-generic
Now you will see the space available has increased in the /boot partition
