searching contents of files

[DeaD_EyE]

with open("a.txt") as master_file:
    keywords = {line.strip() for line in master_file} # this is a set comprehension
    # https://docs.python.org/3/library/stdtypes.html#types-set
    # https://docs.python.org/3/tutorial/datastructures.html#sets
    # this gives you an unique set of the lines in master_file
    # line.strip() removes newlines and whitespace
    # all happens inside memory, if the file is bigger than your memory, this doesn't work

# here you can work with keywords.
# just iterate over the second file, split the line, select the right field and look if this field
# is in keyweords, if True, then do something with the information
# like writing it to a third file