So I have tried to write a Bash script to extract the 10 most common double-vowels words from a file, like good, teeth, etc. Here is what I have so far:

grep -E -o '[aeiou]{2}' $1|tr 'A-Z' 'a-z' |sort|uniq -c|sort -n | tail -10

I tried to use grep with flag E, then find the pattern match, such as 'aa', 'ee', 'ii' , etc, but it is not working at all,