In the previous chapter, we looked at ways to interact with the device interactively using Pexpect and Paramiko. Both of these tools use a persistent session that simulates a user typing in commands as if they are sitting in front of the Terminal. This works fine up to a point. It is easy enough to send commands over for execution on the device and capture the output back. However, when the output becomes more than a few lines of characters, it becomes difficult for a computer program to interpret the output. In order for our simple computer program to automate some of what we do, we need to be able to interpret the returned results and make follow-up actions based on the returned result. When we cannot accurately and predictably interpret the results back, we cannot execute the next command with confidence.
Luckily, this problem was solved by...
