$ uniq deserts.txt
uniq stands for "unique" and filters out adjacent, duplicate lines in a file. Here
uniq deserts.txt filters out duplicates of "Sahara Desert", because the duplicate of 'Sahara Desert' directly follows the previous instance. The "Kalahari Desert" duplicates are not adjacent, and thus remain.
$ sort deserts.txt | uniq
A more effective way to call
uniq is to call
sort to alphabetize a file, and "pipe" the standard output to
uniq. Here by piping
sort deserts.txt to
uniq, all duplicate lines are alphabetized (and thereby made adjacent) and filtered out.
sort deserts.txt | uniq > uniq-deserts.txt
Here we simply send filtered contents to uniq-deserts.txt, which you can view with the