Reviewing some Regular Expressions
Bash shell does not support the +([0-9])-type regular expressions.
- Matches the word VISA in any combination of upper and lowercase letters
- Matches both principle and principal (to catch misspelled words) as well as other words starting with princip and two more letters
- Matches a dollar sign followed by one digit
- Matches any word starting with Fig or fig
- Matching any word that starts with The and is the first word on a line
- Matches any word with an “a” before a “c” (and zero or more letters between them)