How to grep only words which consist of capital characters

Question

I have problem write grep which should grep only those lines, in which is word that consist only from capital characters.

For example I have file : file1.txt

Abc AAA
ADFSD
F
AAAAx

And output should be :

Abc AAA
ADFSD
F

Thank for any advice.

Print line on which is some word that consist only from big letters. — Tempus, Oct 08 '13 at 17:48
Please read descriptions of tags before applying them, in particular those of "linux" and "unix", which simply don't belong here. — Ulrich Eckhardt, Dec 31 '18 at 13:10

Carl Norum · Answer 1 · 2019-11-18T18:40:47.503

15

You can just use:

grep -E '\b[[:upper:]]+\b' file1.txt

That is, look for whole words composed of only uppercase letters.

edited Nov 18 '19 at 18:40

answered Oct 08 '13 at 17:48

Carl Norum

219,201
40
422
469

score 10 · Answer 2 · answered Oct 08 '13 at 17:49

10

This egrep should work:

egrep '\b[A-Z]+\b' file

answered Oct 08 '13 at 17:49

anubhava

761,203
64
569
643

This don't work when `file` contains capitalize word having `_`(e.g. `HELLO_WORLD`) – alhelal Dec 30 '17 at 17:15
`_` is not considered a word boundary so `HELLO_WORLD` is not really a word that consists of only capital letters. – anubhava Dec 30 '17 at 17:24
I think `_` is in word boundary, but not meaningful word boundary. If I am wrong, then you can give me a reference so that I can learn something new. Thank you for giving interesting information. – alhelal Dec 30 '17 at 17:28
See this Q&A: https://stackoverflow.com/questions/1324676/what-is-a-word-boundary-in-regexes – anubhava Dec 30 '17 at 17:31
2

There they say **...with a word character ([0-9A-Za-z_])**. Thank you, very much for such a link. This idea is new to me. – alhelal Dec 30 '17 at 17:40

CS Pei · Answer 3 · 2018-12-31T12:58:22.390

3

This will produce the desired results,

egrep '\b[A-Z]+\b'  file1.txt

Results are

Abc AAA
ADFSD
F

edited Dec 31 '18 at 12:58

answered Oct 08 '13 at 17:46

CS Pei

10,869
1
27
46

The `[^ ]*` would seem to permit mixedCASE? – tripleee Oct 08 '13 at 18:51
Yeah this would allow mixed case; if you just want capitals and underscores, I may suggest `grep -w '\([_]*[A-Z]\+\)\+' file1.txt;` – Alex Walczak Dec 31 '18 at 05:29
(And to allow unlimited underscores out front: `grep -w '[_]*[A-Z]\+[A-Z_]*' file1.txt`) – Alex Walczak Dec 31 '18 at 05:53
@awalllllll you are right, my original answer did allow mixed case. – CS Pei Dec 31 '18 at 12:56
@tripleee, sorry, I was wrong and the answer was updated – CS Pei Dec 31 '18 at 12:58

score 1 · Answer 4 · answered Oct 08 '13 at 17:47

1

GNU grep supports POSIX patterns, so you can simply do:

grep -e '[[:upper:]]' file1.txt

answered Oct 08 '13 at 17:47

Elias Probst

275
1
12

2

Huh? This will find uppercase anywhere. – tripleee Oct 08 '13 at 18:50

Jirka · Answer 5 · 2018-03-30T11:48:27.603

1

If your input contains non-ASCII characters, you may want to use \p{Lu} instead of [A-Z]:

grep -P '\b\p{Lu}+\b' file

For

LONDON 
Paris
MÜNCHEN Berlin

this will return

LONDON
MÜNCHEN Berlin

You can probably list most of these things manually, and as @Skippy-le-grand-gourou says, egrep extends [A-Z] to accented letters, but by using \p{Lu}, you do not need to deal with things like "Since June 2017, however, capital ẞ is accepted as an alternative in the all-caps style"

edited Mar 30 '18 at 11:48

answered Nov 02 '16 at 08:00

Jirka

4,184
30
40

+1 for the working alternative, but FWIW anubhava's answer with `egrep` correctly displays and triggers on accentuated characters. – Skippy le Grand Gourou Mar 29 '18 at 09:41

alhelal · Answer 6 · 2017-12-30T18:18:31.877

1

grep -oP '\b[A-Z0-9_]+\b' file1.txt

This results words consisting of uppercase/digit/_ (e.g. HELLO, NUMBER10, RLIMIT_DATA).

But, this also accept eDw.

edited Dec 30 '17 at 18:18

answered Dec 30 '17 at 17:25

alhelal

916
11
27

score 0 · Answer 7 · answered Oct 08 '13 at 17:58

0

grep '\<[A-Z]*>' file1.txt

answered Oct 08 '13 at 17:58

dono

17
1

1

this do nothing. – alhelal Dec 30 '17 at 17:17

How to grep only words which consist of capital characters

7 Answers7