Morning Removing last character

[sumncguy]

Use str.join

My output:

Output:
deadeye@nexus ~ $ python2.7 parse_ips.py                                                                                                                                                     
Without piping to program, you have to use --input-file
deadeye@nexus ~ $ python2.7 parse_ips.py --input-file                                                                                                                                        
usage: parse_ips.py [-h] [--input-file INPUT_FILE]
parse_ips.py: error: argument --input-file: expected one argument
deadeye@nexus ~ $ python2.7 parse_ips.py --input-file hosts.txt                                                                                                                              
^10\.10\.10\.10$|^10\.10\.10\.11$|^10\.10\.10\.12$|^10\.10\.10\.13$|^10\.10\.10\.14$                                              
deadeye@nexus ~ $ cat hosts.txt | python2.7 parse_ips.py                                                                                                                                     
^10\.10\.10\.10$|^10\.10\.10\.11$|^10\.10\.10\.12$|^10\.10\.10\.13$|^10\.10\.10\.14$

Yep thanks .. I understand that he "." means any char. The App Im pasting into recognizes an ip just so long its wrapped in ^$.

Thanks.

Code:

#!/usr/bin/env python2.7
from __future__ import print_function
import sys
import argparse


def ip2regex(text):
    ips = []
    for row in text.splitlines():
        try:
            ip, hostname = row.split()
        except ValueError:
            # skip errors
            continue
        ip = '^' + ip.replace('.', r'\.') + '$'
        ips.append(ip)
    return '|'.join(ips)


if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument('--input-file', required=False, help='Input file to generate regex output.')
    args = parser.parse_args()
    if args.input_file is None and not sys.stdin.isatty():
        print(ip2regex(sys.stdin.read()))
    elif args.input_file and sys.stdin.isatty():
        with open(args.input_file) as fd:
            print(ip2regex(fd.read()))
    else:
        print('Without piping to program, you have to use --input-file', file=sys.stderr)

Line 15-17 preparing the IP address. By the way, a dot is a metachar in regex. The dot stands for any kind of char.

If you use the dot without escaping it, the regex ^10.10.10.10$ will be also match: 10510710310

PS: split is the opposite of join.

---

Ive seen this construct in some example code .. but not in any instruction .... probably because Im just starting out.

What is it called and where can I learn about it ..

ips = [ip_addr for line in f for ip_addr, *_ in line.split()]