Using egrep to find lines that have 5-6 Upper Case letters. (but not more than 6)

Question

First off, this is homework and unfortunately I have to use egrep (and not with -w or anything of the like).

I need my grep to return lines that have exactly 5 or 6 upper case letters.

Doing egrep [A-Z]{5,6} .filename returns 5 and 6 letter words, but also unfortunately also more letter words than that.

So I for example in this list:

ASK

roger ROBERT gulliver

tom THOMAS

JONATHAN moore

MELISSA tenant

I need it to return only ROBERT and THOMAS.

Answer 1

egrep "^[^A-Z]*[A-Z]{5,6}[^A-Z]*$" .filename

Answer 2

Try with:

egrep '^[A-Z]{5,6}$'

where ^ and $ match beginning and ending of the line, respectively.

Answer 3

Yet another version

a) limited to 5 or 6 Upper Cases in the word;

b) word can have unlimited lower case, plus the '-' and the apostrophe: '

c) uses the \b word edge character (zero-width);

This finds more than your list, (which you would want), and follows all limitations you state. This may result in more than you bargained for, since it also permits any number of lower-case letters between the upper-case letters:

"\b[a-z'-]([A-Z][a-z'-]){5,6}\b"

Will find: awesome JET-LI

Jane DeSILVA

But not: old MacDONALD