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 0.

Example

$ seq 5 | grep -q 3
$ echo $?
0

Here, since grep found pattern "3", it exited with 0 exit code without displaying anything.

$ seq 5 | grep -q 6
$ echo $?
1

Here, grep had non-zero exit code since pattern "6" could not be found.

Source: Linuxize