Thanks a lot for the clarification.
Now, I am using Linux Mint live booting from USB. I run the same command and I get this as output:
[email protected]:~$ cat /etc/*release*
DISTRIB_ID=LinuxMint
DISTRIB_RELEASE=19.1
DISTRIB_CODENAME=tessa
DISTRIB_DESCRIPTION="Linux Mint 19.1 Tessa"
NAME="Linux Mint"...