check storage engine from shell

Easiest way to find the storage engine being used currently.

Inside mongo console type

db.serverStatus().storageEngine

It returns the storage engine being used currently

{ "name" : "wiredTiger" }

Once it is confirmed that wiredTiger is being used then type

db.serverStatus().wiredTiger

to get all the configuration details of wiredTiger.

DISCLAIMER : Not a MongoDB Expert

Check the process list in Linux

WIREDTIGER_CONFIGURED=`ps -ef|grep mongod|grep -i storageengine|grep -ic wiredtiger`
echo ${WIREDTIGER_CONFIGURED}

1 means it's there

From the mongo shell

db.serverStatus()

You should see something like this

"wiredTiger" : {
   ...
   "cache" : {
      "tracked dirty bytes in the cache" : <num>,
      "bytes currently in the cache" : <num>,
      "maximum bytes configured" : <num>,
      "bytes read into cache" :<num>,

or you can just pull the storage engine name with

db.serverStatus().storageEngine.name

You will either get mmapv1 or wiredTiger

or from the command line

MONGO_ENGINE=`mongo -u... -p... --eval "db.serverStatus().storageEngine.name"`