How to check if Hadoop daemons are running?
If you see hadoop process is not running on ps -ef|grep hadoop, run sbin/start-dfs.sh. Monitor with hdfs dfsadmin -report:
[mapr@node1 bin]$ hadoop dfsadmin -reportConfigured Capacity: 105689374720 (98.43 GB)Present Capacity: 96537456640 (89.91 GB)DFS Remaining: 96448180224 (89.82 GB)DFS Used: 89276416 (85.14 MB)DFS Used%: 0.09%Under replicated blocks: 0Blocks with corrupt replicas: 0Missing blocks: 0-------------------------------------------------Datanodes available: 2 (2 total, 0 dead)Name: 192.168.1.16:50010Decommission Status : NormalConfigured Capacity: 52844687360 (49.22 GB)DFS Used: 44638208 (42.57 MB)Non DFS Used: 4986138624 (4.64 GB)DFS Remaining: 47813910528(44.53 GB)DFS Used%: 0.08%DFS Remaining%: 90.48%Last contact: Tue Aug 20 13:23:32 EDT 2013Name: 192.168.1.17:50010Decommission Status : NormalConfigured Capacity: 52844687360 (49.22 GB)DFS Used: 44638208 (42.57 MB)Non DFS Used: 4165779456 (3.88 GB)DFS Remaining: 48634269696(45.29 GB)DFS Used%: 0.08%DFS Remaining%: 92.03%Last contact: Tue Aug 20 13:23:34 EDT 2013
you can use Jps command as vipin said like this command :
/usr/lib/java/jdk1.8.0_25/bin/jps of course you will change the path of java with the one you have "the path you installed java in"
Jps is A nifty tool for checking whether the expected Hadoop processes are running (part of Sun’s Java since v1.5.0).
the result will be something like that :
2287 TaskTracker 2149 JobTracker 1938 DataNode 2085 SecondaryNameNode 2349 Jps 1788 NameNode I get the answer from this tutorial: http://www.michael-noll.com/tutorials/running-hadoop-on-ubuntu-linux-single-node-cluster/