Which linux version we have to do with?

Here is a memo to find it:

Check linux kernel version number

Open a shell prompt and type the following command to see your current Linux kernel version:

$ uname -a

Sample outputs:
Linux vivek-laptop 2.6.32-23-generic-pae #37-Ubuntu SMP Fri Jun 11 09:26:55 UTC 2010 i686 GNU/Linux
Where:
- 2.6.32-23 – Linux kernel version number
- pae – pae kernel type indicate that I’m accssing more than 4GB ram using 32 bit kernel.
- SMP – Kernel that supports multi core and multiple cpus.

/proc/version file

Type the following command to see Linux version info:

$ cat /proc/version

Sample outputs:
Linux version 3.2.0-0.bpo.1-amd64 (Debian 3.2.4-1~bpo60+1) (ben@decadent.org.uk) (gcc version 4.4.5 (Debian 4.4.5-8) ) #1 SMP Sat Feb 11 08:41:32 UTC 2012
The above output identifies the kernel version that is currently running.

Find Distribution Version

Type the following command:

$ cat /etc/*release

OR

$ lsb_release -a

Sample outputs:

No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 10.04 LTS
Release: 10.04
Codename: lucid

Rif: 
https://www.cyberciti.biz/faq/command-to-show-linux-version/