Mastering Python Scripting for System Administrators

Chapter 7, Text Processing and Regular Expressions

1. A regular expression is a method used in programming for pattern matching. Regular expressions provide a flexible and concise means to match strings of text.
2. Following is the answer:

import redef is_allowed_specific_char(string):    charRe = re.compile(r'[^a-zA-Z0-9.]')    string = charRe.search(string)    return not bool(string) print(is_allowed_specific_char("ABCDEFabcdef123450")) print(is_allowed_specific_char("*&%@#!}{"))

3. Answer: a. re is a part of the standard library and can be imported using import re.

4. Answer: a. It will look for the pattern at the beginning and return None if it isn't found.
5. Answer: d. This function returns the entire match.