To check Hadoop daemons are running or not, what you can do is just run the jps command in the shell.
You just have to type 'jps' (make sure JDK is installed in your system). It lists all the running java processes and will list out the Hadoop daemons that are running.
Alternatively, you can use the following command:
ps -ef | grep hadoop | grep -P 'namenode|datanode|tasktracker|jobtracker'
./hadoop dfsadmin -report
You can also check if the daemons are running or not through their web ui.
Learn more about Big Data Architect and its concepts from the Data architect course.