I want to generate the list of packages install in Python 3, the list of all packages in Python 2.7 and find all entries in the 2.7 list not in the Python 3 list.
Generating the list is easy: pip freeze
or pip3.4 freeze
.
Searching for a package in the list is equally trivial pip freeze | grep "wheel"
for example
However, if I want to search for intersections between the list, or in this instance non-intersections I would expect to use something like this pip freeze | grep -n pip3.4 freeze
However it tells me that, obviously the parameter for grep ...is not a file or directory
. My shell scripting is rusty and I vaguely remember there should be a simple way of doing this other than piping both lists to files?