Install urllib2 in Arch Linux

In ArchLinux, the command python defaults to python3. If you neeed to use 2.x, you should run the script with python2 whatever.py.

As aelfric5578 said, python defaults to python3

But if you wish to run it with python3 then you can search the Arch repos with pacman -Ss urllib which will a return a list of packages you can pacman -S

As a naming scheme, Arch sticks to python-libname for python 3 or python2-libname for python2, so it’s usually a safe bet to pacman -S python-missinglib