/regularexpression

Regular Expression Examples

The goal of this script is to provide examples for regular expression.

Learn regular expression from the book Automate the Boring Stuff with Python

Use Regexr Tool to build your regular expression pattern.

Overview

Sub-Section of Running Configuration

The below example pulls the management interface configuration from the show run.

First use the regexr online tool to build the regular expression pattern. Copy and paste the show running-config in the text section. Type the regular expression pattern in the expression field. You can use the cheat sheet for reference.

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import re

with open("switch_config.txt") as read_file:
    config = read_file.read()

pattern = re.compile(r'!\ninterface Management(0|1)\n((?:.|\n)*?)!')
mgmt_config = pattern.search(config).group()

print mgmt_config

Retrieve IP Address

From the management interface configuration, retrieve the IP address.

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import re

with open("switch_config.txt") as read_file:
    config = read_file.read()

pattern = re.compile(r'!\ninterface Management(0|1)\n((?:.|\n)*?)!')
mgmt_config = pattern.search(config).group()

pattern_ip = re.compile(r'((([0-9]){1,3})\.){3}([0-9]){1,3}')
ip_address = pattern_ip.search(mgmt_config).group()

print ip_address