Do not break pipes

Do not break pipes

As the option 'set -e -o pipefail' is very sensite on pipe breaking
stop using '-q' for grep commands.

Otherwise this command (with large enough table) would fail:

 dmsetup table | egrep -q

with exit code 141 (128 + SIGPIPE)

As Peter suggested, he prefers to keep '-o pipefail' - so make sure all
piped commands will read the whole output and will not exit too early.