How to check if Hadoop daemons are running?

Question

What are simple commands to check if Hadoop daemons are running?

For example if I\'m trying to figure out why HDFS is not setup correctly I\'ll want to know a way to ch

Answer 1

I did not find great solution to it, so I used

ps -ef | grep hadoop | grep -P  'namenode|datanode|tasktracker|jobtracker'

just to see if stuff is running

and

./hadoop dfsadmin -report

but last was not helpful until server was running.