Print just 1 results from the whole line

Hi All, need some help with writing a shell script. I tried to search this forum but couldn't find exactly what i want. If you all know any reference link i can read and refer to solve my issue, let me know.

I got 1 file i.e: example.txt. It is content list of data, as below example.

What i am trying do is, i want to read the file and output it to another file with single data. example output like below;

sort -u example.txt

uhu... what a simple command...
how silly i am thanks rdcwayx...