import re
with open('file.txt', 'r') as f:
    text = f.read()
pattern = r"mypattern"
match = re.search(pattern, text)  # Gets the first match
matches = re.findall(pattern, text)  # Gets all matches
text = re.sub(pattern, "replacement", text) # Replaces any matches with "replacement"
print(match) # Prints out the match
print(match.groups()) # Prints out any captured groups