import re

import argparse

import os

def extract_log_values(log_file, patterns):

"""

Extracts values from a log file based on provided regular expression patterns.

Args:

log_file (str): Path to the log file.

patterns (dict): A dictionary where keys are pattern names and values are

regular expression patterns.

Returns:

dict: A dictionary where keys are pattern names and values are lists of

extracted values. Returns an empty dictionary if the file

doesn't exist.

"""

results = {}

try:

with open(log_file, 'r') as f:

log_content = f.read()

except FileNotFoundError:

return {}

for pattern_name, pattern in patterns.items():

matches = re.findall(pattern, log_content)

results[pattern_name] = matches

return results

def main():

parser = argparse.ArgumentParser(description='Extract values from log files.')

parser.add_argument('log_file', help='Path to the log file.')

parser.add_argument('--patterns', nargs='+', help='List of patterns to extract (pattern_name:pattern). Example: --patterns "timestamp:\\d{4}-\\d{2}-\\d{2}" "level:ERROR"')

args = parser.parse_args()

patterns = {}

if args.patterns:

for pattern_str in args.patterns:

try:

name, pattern = pattern_str.split(':', 1)

patterns[name] = pattern

except ValueError:

print(f"Invalid pattern format: {pattern_str}. Use pattern_name:pattern")

return

results = extract_log_values(args.log_file, patterns)

for pattern_name, values in results.items():

print(f"Pattern: {pattern_name}")

for value in values:

print(value)

print("-" * 20)

if __name__ == "__main__":

main()