Use cases

We will now review the topics discussed through some use cases that are being used as common scenarios. These use cases, along with helping us to understand the concepts, can also be leveraged or enhanced to create complex automation that can perform actions at very large scale.

Using regular expressions (regex)

Let us examine a basic use of regex by parsing a base configuration containing the interface configuration of a router.
The task is to identify the interfaces that have trunk enabled:

import re
sampletext="""
interface fa0/1
switchport mode trunk
no shut

interface fa0/0
no shut

interface fa1/0
switchport mode trunk
no shut

interface fa2/0
shut

interface fa2/1
switchport mode trunk
no shut

interface te3...