More redirection: STDOUT to STDIN Finding relevant lines: grep

me@box:~$ cat test.txt test line one test line two TEST LINE TWO DATA LINE TWO test line three

me@box:~$ cat test.txt | grep two test line two

me@box:~$ grep -ir two . test line two TEST LINE TWO DATA LINE TWO

me@box:~$ grep -ir two . | grep -vi data test line two TEST LINE TWO