Command to yield just the linux distribution name only

Suppose I have a set of pre-requisites I need to install for any of a number of linux distributions. In this case, I'd need to switch my install expression against the distribution. I am aware of uname -v, and I am aware that I can inspect the output of this command with some friable string expression and logic. However what I really need is:

V=$(something-like-uname)
echo $V

"Debian"
# or
"Gentoo"
# or
"Redhat"
# or 
"Arch"
# etc.

What is this command? (Does it exist?)