debian 3.16.0-4-amd64 now running on my lap. Now I need `kali Linux. I came to know that kali Linux is based in debian, so is it possible to upgrade (Not sure if I need to downgrade) my current OS to kali Linux. If yes how can I do that. I need to do it from terminal window. Will editing /etc/apt/sources.list allow me to achieve that ?
You should never attempt to convert a Debian into another Debian based distribution, get a Kalilinux installation medium and install it from scratch in another partition. There should not be a problem since you are likely already using grub. You will be able to select it alongside of Debian whenever you boot.
3.16.0-4-amd64 is the version of the kernel you are running. Here is a good summary on how to update your Debian system though.
You can see the Debian release you are using by doing this (probably jessie):
For me that is:
PRETTY_NAME="Debian GNU/Linux 9 (stretch)" NAME="Debian GNU/Linux" VERSION_ID="9" VERSION="9 (stretch)"
Also in future when you desire information about a certain version of a linux distro you might also post the output of
uname --all which would look something like this:
Linux $hostname 4.9.0-3-amd64 #1 SMP Debian 4.9.30-2+deb9u2 (2017-06-26) x86_64 GNU/Linux
Adding to Sheppy's answer I wouldn't recommend jumping straight from any other version to another one except for the next version.
The version of GNU/Linux kernel you have or are using is 3.16 which is used in jessie.
The one sheppy is using is 4.9.0-3 which is used in stretch
and I am using which is currently being used in buster.
─[$] uname -a Linux debian 4.11.0-1-amd64 #1 SMP Debian 4.11.6-1 (2017-06-19) x86_64 GNU/Linux
[$] apt-cache policy linux-image-4.11.0-2-amd64 linux-image-4.11.0-2-amd64: Installed: (none) Candidate: 4.11.11-1+b1 Version table: 4.11.11-1+b1 1 1 http://httpredir.debian.org/debian unstable/main amd64 Packages
There isn't much of a benefit unless you have either one of the newest processors or are have bugs in an old kernel release and know that is changed in any of the newer versions.
If you do want to upgrade nonetheless, I would suggest editing your /etc/apt/sources.list putting the newer release name, do either an
apt update , update the index and then install the newer kernel version, reboot the system and see everything is fine. You 'could' also take your time and upgrade components one by one but it's a long process and possibility of breakage is possible. Even if everything goes your way, it's time consuming.
On the other hand, if you freshly install stretch you would get bugfixes while partitioning for filesystem you choose and many other things as well.
Another thing you could and should do is -
$ apt list --installed | less
Hope the above gave you something to chew about :)