$grep -n root /etc/passwd 1:root:x:0:0:root:/root:/bin/bash $ $cat hello.txt hello world $grep -v hello hello.txt world $ $cat hello.txt hello world helloo $grep -c hello hello.txt 2 $grep -c helloo hello.txt 1 $ $cat hello.txt hello world helloo Hello $grep hello hello.txt hello helloo $grep -i hello hello.txt hello helloo Hello $