Slightly more useful than grep, but doesn't make you want to punch the computer like sed or cut.

reg_match

#!/usr/bin/env python

from __future__ import print_function, unicode_literals

import argparse
import re
from sys import stdin

parser = argparse.ArgumentParser()

parser.add_argument('-o', '--output')
parser.add_argument('-a', '--front', action='store_true', help=
    'Anchor the match at the front of each line')
parser.add_argument('-b', '--back', action='store_true', help=
    'Anchor the match at the back of each line')
parser.add_argument('-c', '--lock', action='store_true', help=
    'Anchor the match at the fron and back of each line')
parser.add_argument('-s', '--sep', default='\t', help=
    'The character with which to separate groups under standard format')
parser.add_argument('-i', '--ignore-case', action='store_true')
parser.add_argument('regex')
parser.add_argument('files', nargs='*')

def match(regex, istr, output):
    for line in istr:
        line = line.rstrip('\n')
        match = regex.search(line)
        if match:
            print(match.expand(output))

def make_regex(args):
    base = args.regex
    if args.lock or args.front:
        base = '\A' + base
    if args.lock or args.back:
        base = base + '\Z'
    
    flags = 0
    if args.ignore_case:
        flags = flags | re.I
    
    return re.compile(base, flags)

def make_output(regex, output, sep):
    if output:
        return output
    elif regex.groups != 0:
        return sep.join('\g<{0}>'.format(i+1) for i in range(regex.groups))
    else:
        return '\g<0>'

def run(regex, output, files):
    if files:
        for name in files:
            print('{0}:'.format(name))
            with open(name) as f:
                match(regex, f, output)
    else:
        match(regex, stdin, output)

def main():
    args = parser.parse_args()
    regex = make_regex(args)
    run(regex, make_output(regex, args.output, args.sep), args.files)

if __name__ == '__main__':
    main()