Bash extract after substring and before substring

Question

Say I have a string:

random text before authentication_token = 'pYWastSemJrMqwJycZPZ', gravatar_hash = 'd74a97f

I want a shell command to extract everything after "authentication_token = '" and before the next '.

So basically, I want to return pYWastSemJrMqwJycZPZ.

How do I do this?

Answer 1

Use parameter expansion:

#!/bin/bash
text="random text before authentication_token = 'pYWastSemJrMqwJycZPZ', gravatar_hash = 'd74a97f"
token=${text##* authentication_token = \'}   # Remove the left part.
token=${token%%\'*}                          # Remove the right part.
echo "$token"

Note that it works even if random text contains authentication token = '...'.