explainshell.com - cat.1posix a b c %7C grep %27%5Eii%27 %7C awk %27%7Bprint %242%7D%27 %7C sort %7C uniq

a b c %7C grep %27%5Eii%27 %7C awk %27%7Bprint %242%7D%27 %7C sort %7C uniq

concatenate and print files

source manpages: cat