mongod: unrecognized service , mongod.service is present already

I had the same problem after pulling the ubuntu:17:04 docker image and installing mongodb-org

It looks like Mongodb created a systemd startup file which was already replaced by upstart.

As a workaround:

1. Create a new file /etc/init/mongod.conf (requires sudo rights). You can use: sudo gedit /etc/init/mongod.conf

2. Paste the following contents into the newly created upstart file:

   # Ubuntu upstart file at /etc/init/mongod.conf
   
   # Recommended ulimit values for mongod or mongos
   # See http://docs.mongodb.org/manual/reference/ulimit/#recommended-settings
   #
   limit fsize unlimited unlimited
   limit cpu unlimited unlimited
   limit as unlimited unlimited
   limit nofile 64000 64000
   limit rss unlimited unlimited
   limit nproc 64000 64000
   
   kill timeout 300 # wait 300s between SIGTERM and SIGKILL.
   
   pre-start script
     DAEMONUSER=${DAEMONUSER:-mongodb}
     if [ ! -d /var/lib/mongodb ]; then
       mkdir -p /var/lib/mongodb && chown mongodb:mongodb /var/lib/mongodb
     fi
     if [ ! -d /var/log/mongodb ]; then
       mkdir -p /var/log/mongodb && chown mongodb:mongodb /var/log/mongodb
     fi
     touch /var/run/mongodb.pid
     chown $DAEMONUSER /var/run/mongodb.pid
   end script
   
   start on runlevel [2345]
   stop on runlevel [06]
   
   script
     ENABLE_MONGOD="yes"
     CONF=/etc/mongod.conf
     DAEMON=/usr/bin/mongod
     DAEMONUSER=${DAEMONUSER:-mongodb}
     DAEMONGROUP=${DAEMONGROUP:-mongodb}
   
     if [ -f /etc/default/mongod ]; then . /etc/default/mongod; fi
   
     # Handle NUMA access to CPUs (SERVER-3574)
     # This verifies the existence of numactl as well as testing that the command works
     NUMACTL_ARGS="--interleave=all"
     if which numactl >/dev/null 2>/dev/null && numactl $NUMACTL_ARGS ls / >/dev/null 2>/dev/null
     then
       NUMACTL="$(which numactl) -- $NUMACTL_ARGS"
       DAEMON_OPTS=${DAEMON_OPTS:-"--config $CONF"}
     else
       NUMACTL=""
       DAEMON_OPTS="-- "${DAEMON_OPTS:-"--config $CONF"}
     fi
   
     if [ "x$ENABLE_MONGOD" = "xyes" ]
     then
       exec start-stop-daemon --start \
           --chuid $DAEMONUSER:$DAEMONGROUP \
           --pidfile /var/run/mongodb.pid \
           --make-pidfile \
           --exec $NUMACTL $DAEMON $DAEMON_OPTS
     fi
   end script
   

3. Now, you can use the following commands:

   sudo service mongod start

   sudo service mongod stop

   sudo service mongod status

reference: https://github.com/mongodb/mongo/blob/master/debian/mongod.upstart

I kept getting the same error when trying to start the mongo service. mongod worked, but then I need to keep one terminal window open to use mongo in another. nothing else worked for me except this:

'mongod --fork --logpath /var/log/mongodb.log'

Above command starts the mongo daemon if you don't already have it started and then you can just type 'mongo' in command line and mongo works

(from here: https://docs.mongodb.com/manual/tutorial/manage-mongodb-processes/)

I removed mongo lock file first

sudo rm /var/lib/mongodb/mongod.lock

then started the mongod using the following command

sudo mongod --fork -f /etc/mongod.conf