How do I grep for all words that are less than 4 characters?

问题

I have a dictionary with words separated by line breaks.

回答1:

You can just do:

egrep -x '.{1,3}' myfile

This will also skip blank lines, which are technically not words. Unfortunately, the above reg-ex will count apostrophes in contractions as letters as well as hyphens in hyphenated compound words. Hyphenated compound words are not a problem at such a low letter count, but I am not sure whether or not you want to count apostrophes in contractions, which are possible (e.g., I'm). You can try to use a reg-ex such as:

egrep -x '\w{1,3}' myfile

..., but this will only match upper/lower case letters and not match contractions or hyphenated compound words at all.

回答2:

Like this: grep -v "^...." my_file

回答3:

Try this regular expression:

grep -E '^.{1,3}$' your_dictionary

来源：https://stackoverflow.com/questions/4982052/how-do-i-grep-for-all-words-that-are-less-than-4-characters