All mapreduce commands are invoked by the bin/mapred script. Running the mapred script without any arguments prints the description for all commands.
Usage: mapred [SHELL_OPTIONS] COMMAND [GENERIC_OPTIONS] [COMMAND_OPTIONS]
Hadoop has an option parsing framework that employs parsing generic options as well as running classes.
| COMMAND_OPTIONS | Description |
|---|---|
| SHELL_OPTIONS | The common set of shell options. These are documented on the Hadoop Commands Reference page. |
| GENERIC_OPTIONS | The common set of options supported by multiple commands. See the Hadoop Commands Reference for more information. |
| COMMAND COMMAND_OPTIONS | Various commands with their options are described in the following sections. The commands have been grouped into User Commands and Administration Commands. |
Commands useful for users of a hadoop cluster.
Creates a hadoop archive. More information can be found at Hadoop Archives Guide.
Prints the class path needed to get the Hadoop jar and the required libraries.
Usage: mapred classpath
Copy file or directories recursively. More information can be found at Hadoop DistCp Guide.
Command to interact with Map Reduce Jobs.
Usage: mapred job | [GENERIC_OPTIONS] | [-submit <job-file>] | [-status <job-id>] | [-counter <job-id> <group-name> <counter-name>] | [-kill <job-id>] | [-events <job-id> <from-event-#> <#-of-events>] | [-history [all] <jobOutputDir>] | [-list [all]] | [-kill-task <task-id>] | [-fail-task <task-id>] | [-set-priority <job-id> <priority>]
| COMMAND_OPTION | Description |
|---|---|
| -submit job-file | Submits the job. |
| -status job-id | Prints the map and reduce completion percentage and all job counters. |
| -counter job-id group-name counter-name | Prints the counter value. |
| -kill job-id | Kills the job. |
| -events job-id from-event-# #-of-events | Prints the events’ details received by jobtracker for the given range. |
| -history [all]jobOutputDir | Prints job details, failed and killed tip details. More details about the job such as successful tasks and task attempts made for each task can be viewed by specifying the [all] option. |
| -list [all] | Displays jobs which are yet to complete. -list all displays all jobs. |
| -kill-task task-id | Kills the task. Killed tasks are NOT counted against failed attempts. |
| -fail-task task-id | Fails the task. Failed tasks are counted against failed attempts. |
| -set-priority job-id priority | Changes the priority of the job. Allowed priority values are VERY_HIGH, HIGH, NORMAL, LOW, VERY_LOW |
Runs a pipes job.
Usage: mapred pipes [-conf <path>] [-jobconf <key=value>, <key=value>, ...] [-input <path>] [-output <path>] [-jar <jar file>] [-inputformat <class>] [-map <class>] [-partitioner <class>] [-reduce <class>] [-writer <class>] [-program <executable>] [-reduces <num>]
| COMMAND_OPTION | Description |
|---|---|
| -conf path | Configuration for job |
| -jobconf key=value, key=value, … | Add/override configuration for job |
| -input path | Input directory |
| -output path | Output directory |
| -jar jar file | Jar filename |
| -inputformat class | InputFormat class |
| -map class | Java Map class |
| -partitioner class | Java Partitioner |
| -reduce class | Java Reduce class |
| -writer class | Java RecordWriter |
| -program executable | Executable URI |
| -reduces num | Number of reduces |
command to interact and view Job Queue information
Usage: mapred queue [-list] | [-info <job-queue-name> [-showJobs]] | [-showacls]
| COMMAND_OPTION | Description |
|---|---|
| -list | Gets list of Job Queues configured in the system. Along with scheduling information associated with the job queues. |
| -info job-queue-name [-showJobs] | Displays the job queue information and associated scheduling information of particular job queue. If -showJobs options is present a list of jobs submitted to the particular job queue is displayed. |
| -showacls | Displays the queue name and associated queue operations allowed for the current user. The list consists of only those queues to which the user has access. |
Commands useful for administrators of a hadoop cluster.
Runs a MapReduce hsadmin client for execute JobHistoryServer administrative commands.
Usage: mapred hsadmin [-refreshUserToGroupsMappings] | [-refreshSuperUserGroupsConfiguration] | [-refreshAdminAcls] | [-refreshLoadedJobCache] | [-refreshLogRetentionSettings] | [-refreshJobRetentionSettings] | [-getGroups [username]] | [-help [cmd]]
| COMMAND_OPTION | Description |
|---|---|
| -refreshUserToGroupsMappings | Refresh user-to-groups mappings |
| -refreshSuperUserGroupsConfiguration | Refresh superuser proxy groups mappings |
| -refreshAdminAcls | Refresh acls for administration of Job history server |
| -refreshLoadedJobCache | Refresh loaded job cache of Job history server |
| -refreshJobRetentionSettings | Refresh job history period, job cleaner settings |
| -refreshLogRetentionSettings | Refresh log retention period and log retention check interval |
| -getGroups [username] | Get the groups which given user belongs to |
| -help [cmd] | Displays help for the given command or all commands if none is specified. |