New in version 2.4.
The text search is currently a beta feature. As a beta feature:
You can enable the text search feature at startup with the textSearchEnabled parameter:
mongod --setParameter textSearchEnabled=true
Additionally, you can enable the feature in the mongo shell with the setParameter command. This command does not propagate from the primary to the secondaries. You must enable on each and every mongod for replica sets.
You must set the parameter every time you start the server. You may prefer to add the parameter to the configuration files.