Run-time Database Configuration  The command line and
configuration file interfaces provide MongoDB administrators
with a large number of options and settings for controlling the
operation of the database system. This document provides an
overview of common configurations and examples of best-practice
configurations for common use cases.  While both interfaces
provide access to the same collection of options and settings,
this document primarily uses the configuration file interface.
If you run MongoDB using a control script or installed from a
package for your operating system, you likely already have a
configuration file located at /etc/mongodb.conf. Confirm this by
checking the contents of the /etc/init.d/mongod or
/etc/rc.d/mongod script to ensure that the control scripts start
the mongod with the appropriate configuration file (see below.)
To start a MongoDB instance using this configuration issue a
command in the following form:  mongod --config
/etc/mongodb.conf mongod -f /etc/mongodb.conf  Modify the