yes, Patrick is right. If you type nc you will see the available supported flags. For example, Usage: nc [OPTIONS] HOST PORT - connect nc [OPTIONS] -l -p PORT [HOST] [PORT] - listen
-e PROG Run PROG after connect (must be last) -l Listen mode, for inbound connects -lk With -e, provides persistent server -p PORT Local port -s ADDR Local address -w SEC Timeout for connects and final net reads -i SEC Delay interval for lines sent -n Don’t do DNS resolution -u UDP mode -v Verbose -o FILE Hex dump traffic -z Zero-I/O mode (scanning) -q was used to wait for x seconds for a response to come back from the server. This usually helps to give some secs for the server to respond and reduce false positives if any. On the same note, I would suggest using *zkServer.sh status *command and grep the mode to see in which mode an instance is running. In the cluster, the zookeeper runs in either leader or a follower. So this enhances the healthcheck and guarantees that the zookeeper cluster is running as well as it is in a quorum (which I believe is a good thing :) ) On Thu, Oct 29, 2020 at 9:25 AM Patrick Hunt <[email protected]> wrote: > I believe it depends which version of netcat you're using, see the > following for background: > https://issues.apache.org/jira/browse/ZOOKEEPER-737 > > Regards, > > Patrick > > On Thu, Oct 29, 2020 at 6:18 AM Debraj Manna <[email protected]> > wrote: > > > Anyone any thoughts on this one? Same has been asked in stackoverflow > also > > > > > > > https://stackoverflow.com/questions/64587307/correct-way-to-check-zookeepers-running-mode > > > > On Wed, Oct 28, 2020 at 9:37 PM Debraj Manna <[email protected]> > > wrote: > > > > > Hi > > > > > > Can someone let me know what is the recommended way to check if > zookeeper > > > is running via netcat? > > > > > > The documentation > > > <https://zookeeper.apache.org/doc/r3.5.2-alpha/zookeeperAdmin.html> > > > states echo "isro" | nc localhost 2181 . > > > > > > But in few places it is recommended to use -q with netcat > > > > > > https://stackoverflow.com/a/28424409/785523 > > > > > > Can someone let me know if -q is needed ? > > > > > > > > > - Zookeeper Version 3.4.13 > > > - OS - Ubuntu 18 > > > > > > > > >
