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.

Solution 1

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

Solution 2

Try with:

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

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

Comments

[Zerg12]

+1 all around, I wish I had more opportunity to use regexp's in my work life!

[roger34]

Forgot to mention that the words in the list were not at the start or end of the lines, my bad. Geeklab below had the right formula for the alternate version. Thanks for the help.

[Geeklab]

Update: you are explicitly talking about no more than 7 uppercase letters. I'm not sure what you want with lowercase. My regexp does allow xROBERTx, while cYrus' regexp refuses it.