Find Duplicate/Repeated or Unique words in file spanning across multiple lines

Question

in Linux, I have a text file which have duplicate words like this

abc line 1
xyz zzz
123 456
abc end line

Now I want to print only all DUPLICATE words (which is abc) how ?

Answer 1

You can tokenize the words with grep -wo and find consecutive duplicates with uniq -d, add -c to count the number of duplicates, e.g.:

grep -wo '[[:alnum:]]\+' infile | sort | uniq -cd

Output:

2 abc
2 line