If you have a file with several lines that contains email addresses that you like to extract, you can do that with Linux grep command:
File “emails.txt”:
somestreng anotherstring 342345 somename.lastname@domain.com
where somename.lastname@domain.com is the string you like to extract:
you can do this with:
grep -EiEio '\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b' emails.txt
Result:
somename.lastname@domain.com