Apache Hadoop Commands
In this tutorial, we will see the list of Hadoop commands which are used to perform multiple tasks like submit jobs, check the status of jobs, kill jobs, check the list of jobs, command to format namenode, command to rollback namenode in its previous state and so on.
| Commands | Description |
|---|---|
| $hadoop job -submit | This command is used to submit the job. |
| $hadoop job -status | This command is used to print the map and reduce the end percentage and all job counters. |
| $hadoop job -counter | This command will print group-name counter-name and counter value. |
| $hadoop job -kill job-id | This command will kill the job. |
| $hadoop job -events job-id from-event-# #-of-events. | This command is used to imprint the event details received by the job tracker for the delivered scope. |
| $hadoop job -history [all]jobOutputDir | This command is used to print job details such as the job is completed, failed, or killed. The option (all) will give more details such as successful tasks and the attempts composed for each task. |
| $hadoop job -list [all] | This command will display jobs that are yet to complete. |
| $hadoop job -kill-task task-id | This command will kill the task. |
| $hadoop job -fail-task task-id | This command will fail the task. |
| $hadoop job -set-priority job-id priority | This command will change the priority of the job. The values allowed for priority are very high, high, normal, low, and very low. |
| $hadoop dfsadmin -report | This command is used to describe the filesystem. |
| $hadoop dfsadmin -refreshNodes | This command will re-read the hosts and exclude files to update the set of Datanodes that are allowed to connect to the Namenode and those that should be decommissioned or recommissioned. |
| $hadoop dfsadmin -finalizeUpgrade | This command will finalize the upgrade of HDFS. |
| $hadoop dfsadmin -upgradeProgress status / details / force | This command will request the current distributed upgrade status, a detailed status, or force the upgrade to proceed. |
| $hadoop dfsadmin -metasave filename | This command saves the Namenode's fundamental data structures to the filename in the directory named by hadoop.log.dir property. |
| $hadoop dfsadmin -restoreFailedStorage true / false / check | This command is used to turn on/off planned effort to recover broken storage replicas. |
| $hadoop namenode -format | This command will format the namenode. |
| $hadoop namenode -rollback | This command is used to revert the namenode to the earlier version. This command is used when the Hadoop cluster is stopped. |
| $hadoop namenode -finalize | This command will remove the previous state of the files system. The recent upgrade will become permanent. The rollback option will not be available anymore. Once the finalization is completed post that, the namenode is shutdown. |
| $hadoop namenode -importCheckpoint | This command will load an image from a checkpoint directory and save it into the current one. Checkpoint dir is read from property fs. checkpoint. dir. |