Grep Quiet Mode
We can use
-q, --quiet argument which tells
grep to run in quiet mode and not display anything on standard output. If a match is found,
grep will exit with a status code of
$ seq 5 | grep -q 3 $ echo $? 0
grep found pattern “3”, it exited with
0 exit code without displaying anything.
$ seq 5 | grep -q 6 $ echo $? 1
grep had non-zero exit code since pattern “6” could not be found.