Interactive help in Python REPL

$ python

>>> help()

help> str.join

Help on method_descriptor in str:

str.join = join(...)
    S.join(iterable) -> string
   
    Return a string which is the concatenation of the strings in the
    iterable.  The separator between elements is S.
(END)

# Press Q to exit

Keep environment variable while using sudo

$ export A="B"

# Use -E to keep the above environment variable
$ sudo -E python a.py