new_parser.py

#prints to console and creates and writes to a seperate file.

import re
user_input = input("What would you like to search for?\n")
err_occur = [] # The list where we will store results.
pattern = re.compile(user_input, re.IGNORECASE) # Compile a case-insensitive regex pattern.
try: # Try to:
    date_time = input("Date and time of the file?\n")
    with open ('output_log__{}.txt'.format(date_time), 'rt') as in_file: # open file for reading text.
        with open(user_input+'_'+date_time+'.txt', 'w') as wf: # Creates a file to write to using user input from above
            for linenum, line in enumerate(in_file): # Iterate on file per line, keeping track of line numbers.
                if pattern.search(line) != None: # If substring search finds a match,
                    err_occur.append((linenum, line.rstrip('\n'))) # strip linebreaks, store line and line number in list as tuple.
                    for linenum, line in err_occur: # Iterate over the list of tuples, and
                        print("Line ", linenum, ": ", line, sep='') # print results as "Line [linenum]: [line]".
                        wf.write(line+"\n")
except FileNotFoundError: # If log file not found,
    print("Log file not found.") # print an error message.
    print("year-month-day__hour-minute-second")