grep whole words made of only uppercase letters

Question

Seems like this is rather simple, but I\'m having trouble.

I have a text document that looks, for example, like this:

This is a
TEXT DOCUME

Answer 1

To complement Zbynek Vyskovsky - kvr000's helpful answer:

grep's -E option allows use of extended regular expression, which includes quantifier + to mean one or more, which simplifies the solution:

 grep -Eo '\<[[:upper:]]+\>' Untitled.txt

Also, as mentioned in Benjamin W.'s answer, -w can be used to match on word boundaries without having to specify it as part of the regex:

 grep -Ewo '[[:upper:]]+' Untitled.txt

Note, however, that -w is a nonstandard option (but both BSD/OSX and GNU grep implement it).

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As for egrep: it is nothing more than an (effective) alias of grep -E, which, as stated, activates support for extended regular expressions, but the exact set of features is platform-dependent.

Additionally, only GNU grep supports the -P option to support PCREs (Perl-Compatible Regular Expression), which offer even more features and flexibility.