Euouae¹ (pronunciation: juːˈuːɪ²) — six letters long — is the longest English word consisting only of vowels. It's also the English word with the most consecutive vowels. Words with five consecutive vowels include cooeeing and queueing. Euouae is an abbreviation used in Latin psalters³ and other liturgical books⁴ to show the distribution of syllables in the differentia or variable melodic endings⁵ of the standard Psalm tones⁶ of Gregorian chant⁷.

One of the longest English words consisting strictly of alternating consonants and vowels is hepatoperitonitis: a medical term for the inflammation of the part of the peritoneum surrounding the liver.

One of the longest English words in which no letter appears more than once is dermatoglyphics¹¹: the scientific study of fingerprints, lines, mounts and shapes of hands.

Assignment

The current directory contains the text file words.txt¹² containing a list of English words. Each word is on a separate line and only consists of uppercase letters. Use a command from the grep family to restrict the list to the words with the following odd properties:

1. all words that can be played on a piano; these are all words that only consist of uppercase letters that are used to denote chords: A, B, C, D, E, F and G

2. all words that remain unchanged when mirrored horizontally; these are all words that only consist of the uppercase letters B, C, D, E, H, I, K, O and X

3. all words that contain at least five consecutive vowels; the vowels are the letters A, E, I, O and U

4. all words in which no letter appears more than once

5. all words consisting strictly of alternating consonants and vowels

6. all words whose letters are arranged in alphabetical order; consecutive occurrences of the same letter are allowed

7. all words that start and end with the same substring of at least four letters, without any overlap between the two substrings

Try to keep the regular expressions as concise as possible.