pygrep

#!/usr/bin/python
"""
Yet Another grep.
But user friendly.

sudo ln -s ./pygrep /usr/local/bin
"""
import re
import click
import sys


@click.group()
def main():
    pass


@main.command()
@click.argument('match_pattern')
@click.argument('replacement_pattern')
@click.argument('input', type=click.File('r'), default='-')
def replace_match(match_pattern, replacement_pattern, input):
    """
    Replaces the first matching part of each line with the replacement pattern.
    """
    r = re.compile(match_pattern)
    for line in input:
        print r.sub(replacement_pattern, line)


@main.command()
@click.argument('match_pattern')
@click.argument('input', type=click.File('r'), default='-')
@click.option('-g', '--group', default=-1)
def print_match(match_pattern, group, input):
    """
    Prints the first part of each line matching a pattern.
    group option:
        - < 0: prints the whole match if no capturing group specified, otherwise
               prints only the first capturing group.
        - = 0: prints the whole match
        - > 0: prints only the specified capturing group
    """

    r = re.compile(match_pattern)
    for line in input:
        match = r.search(line)
        if match:
            if group >= 0:
                print match.group(group)
            elif match.groups():
                print match.group(1)
            else:
                print match.group(0)


@main.command()
@click.argument('match_pattern')
@click.argument('input', type=click.File('r'), default='-')
def print_line(match_pattern, input):
    """
    Prints the lines matching the given pattern.
    """
    r = re.compile(match_pattern)
    for line in input:
        match = r.search(line)
        if match:
            print line


if __name__ == '__main__':
    main()