Way to find variable=value using sed & awk in bash

Question

How to extract variable=value in a string using sed & awk?

e.g. consider following string,

Hi Folks how are you. I want to extract birthdate=July0808128 from this string.

Answer 1

$ s="birthdate=July0808128"

$ echo "${s%=*}"
birthdate

$ echo "${s#*=}"
July0808128

--edit--

I have file which many lines. out of which 3 lines are like, >Hi Rock how are you. I want to extract birthdate=July0808128 from this string. >Hi Akshay how are you. I want to extract birthdate=July0808128 from this string. I want to extract birthdate=July0808128 out of above string

grep -Po 'birthdate=\w+' yourfile 

OR

grep -Po 'birthdate=\w+[0-9]{7}' yourfile

Should work.