All of the Hadoop commands and subprojects follow the same basic structure:
Usage: shellcommand [SHELL_OPTIONS] [COMMAND] [GENERIC_OPTIONS] [COMMAND_OPTIONS]
| FIELD | Description |
|---|---|
| shellcommand | The command of the project being invoked. For example, Hadoop common uses hadoop, HDFS uses hdfs, and YARN uses yarn. |
| SHELL_OPTIONS | Options that the shell processes prior to executing Java. |
| COMMAND | Action to perform. |
| GENERIC_OPTIONS | The common set of options supported by multiple commands. |
| COMMAND_OPTIONS | Various commands with their options are described in this documention for the Hadoop common sub-project. HDFS and YARN are covered in other documents. |
All of the shell commands will accept a common set of options. For some commands, these options are ignored. For example, passing ---hostnames on a command that only executes on a single host will be ignored.
| SHELL_OPTION | Description |
|---|---|
| --buildpaths | Enables developer versions of jars. |
| --config confdir | Overwrites the default Configuration directory. Default is $HADOOP_PREFIX/etc/hadoop. |
| --daemon mode | If the command supports daemonization (e.g., hdfs namenode), execute in the appropriate mode. Supported modes are start to start the process in daemon mode, stop to stop the process, and status to determine the active status of the process. status will return an LSB-compliant result code. If no option is provided, commands that support daemonization will run in the foreground. For commands that do not support daemonization, this option is ignored. |
| --debug | Enables shell level configuration debugging information |
| --help | Shell script usage information. |
| --hostnames | When --slaves is used, override the slaves file with a space delimited list of hostnames where to execute a multi-host subcommand. If --slaves is not used, this option is ignored. |
| --hosts | When --slaves is used, override the slaves file with another file that contains a list of hostnames where to execute a multi-host subcommand. If --slaves is not used, this option is ignored. |
| --loglevel loglevel | Overrides the log level. Valid log levels are FATAL, ERROR, WARN, INFO, DEBUG, and TRACE. Default is INFO. |
| --slaves | If possible, execute this command on all hosts in the slaves file. |
Many subcommands honor a common set of configuration options to alter their behavior:
| GENERIC_OPTION | Description |
|---|---|
| -archives <comma separated list of archives> | Specify comma separated archives to be unarchived on the compute machines. Applies only to job. |
| -conf <configuration file> | Specify an application configuration file. |
| -D <property>=<value> | Use value for given property. |
| -files <comma separated list of files> | Specify comma separated files to be copied to the map reduce cluster. Applies only to job. |
| -jt <local> or <resourcemanager:port> | Specify a ResourceManager. Applies only to job. |
| -libjars <comma seperated list of jars> | Specify comma separated jar files to include in the classpath. Applies only to job. |
All of these commands are executed from the hadoop shell command. They have been broken up into User Commands and Admininistration Commands.
Commands useful for users of a hadoop cluster.
Creates a hadoop archive. More information can be found at Hadoop Archives Guide.
Usage: hadoop checknative [-a] [-h]
| COMMAND_OPTION | Description |
|---|---|
| -a | Check all libraries are available. |
| -h | print help |
This command checks the availability of the Hadoop native code. See #NativeLibraries.html for more information. By default, this command only checks the availability of libhadoop.
Usage: hadoop classpath [--glob |--jar <path> |-h |--help]
| COMMAND_OPTION | Description |
|---|---|
| --glob | expand wildcards |
| --jar path | write classpath as manifest in jar named path |
| -h, --help | print help |
Prints the class path needed to get the Hadoop jar and the required libraries. If called without arguments, then prints the classpath set up by the command scripts, which is likely to contain wildcards in the classpath entries. Additional options print the classpath after wildcard expansion or write the classpath into the manifest of a jar file. The latter is useful in environments where wildcards cannot be used and the expanded classpath exceeds the maximum supported command line length.
Usage: hadoop credential <subcommand> [options]
| COMMAND_OPTION | Description |
|---|---|
| create alias [-provider provider-path] | Prompts the user for a credential to be stored as the given alias. The hadoop.security.credential.provider.path within the core-site.xml file will be used unless a -provider is indicated. |
| delete alias [-provider provider-path] [-f] | Deletes the credential with the provided alias. The hadoop.security.credential.provider.path within the core-site.xml file will be used unless a -provider is indicated. The command asks for confirmation unless -f is specified |
| list [-provider provider-path] | Lists all of the credential aliases The hadoop.security.credential.provider.path within the core-site.xml file will be used unless a -provider is indicated. |
Command to manage credentials, passwords and secrets within credential providers.
The CredentialProvider API in Hadoop allows for the separation of applications and how they store their required passwords/secrets. In order to indicate a particular provider type and location, the user must provide the hadoop.security.credential.provider.path configuration element in core-site.xml or use the command line option -provider on each of the following commands. This provider path is a comma-separated list of URLs that indicates the type and location of a list of providers that should be consulted. For example, the following path: user:///,jceks://file/tmp/test.jceks,jceks://hdfs@nn1.example.com/my/path/test.jceks
indicates that the current user’s credentials file should be consulted through the User Provider, that the local file located at /tmp/test.jceks is a Java Keystore Provider and that the file located within HDFS at nn1.example.com/my/path/test.jceks is also a store for a Java Keystore Provider.
When utilizing the credential command it will often be for provisioning a password or secret to a particular credential store provider. In order to explicitly indicate which provider store to use the -provider option should be used. Otherwise, given a path of multiple providers, the first non-transient provider will be used. This may or may not be the one that you intended.
Example: hadoop credential list -provider jceks://file/tmp/test.jceks
Usage: hadoop distch [-f urilist_url] [-i] [-log logdir] path:owner:group:permissions
| COMMAND_OPTION | Description |
|---|---|
| -f | List of objects to change |
| -i | Ignore failures |
| -log | Directory to log output |
Change the ownership and permissions on many files at once.
Copy file or directories recursively. More information can be found at Hadoop DistCp Guide.
This command is documented in the File System Shell Guide. It is a synonym for hdfs dfs when HDFS is in use.
Usage: hadoop jar <jar> [mainClass] args...
Runs a jar file.
Use yarn jar to launch YARN applications instead.
Usage: hadoop kerbname principal
Convert the named principal via the auth_to_local rules to the Hadoop user name.
Example: hadoop kerbname user@EXAMPLE.COM
View and modify Hadoop tracing settings. See the Tracing Guide.
Commands useful for administrators of a hadoop cluster.
Usage:
hadoop daemonlog -getlevel <host:httpport> <classname> hadoop daemonlog -setlevel <host:httpport> <classname> <level>
| COMMAND_OPTION | Description |
|---|---|
| -getlevel host:httpport classname | Prints the log level of the log identified by a qualified classname, in the daemon running at host:httpport. This command internally connects to http://<host:httpport>/logLevel?log=<classname> |
| -setlevel host:httpport classname level | Sets the log level of the log identified by a qualified classname, in the daemon running at host:httpport. This command internally connects to http://<host:httpport>/logLevel?log=<classname>&level=<level> |
Get/Set the log level for a Log identified by a qualified class name in the daemon.
Example: $ bin/hadoop daemonlog -setlevel 127.0.0.1:50070 org.apache.hadoop.hdfs.server.namenode.NameNode DEBUG