Bash : grep unique lines

Question

I'd like to grep unique line. This is the file content:

this is line 1
this is line 1
this is line 2
this is line 1
this is line 1

I just want to output this is line 2 to my shell. How can I do that?

Answer 1

sort x.txt |uniq -u

assuming your file is in x.txt which gives

this is line 2