Some of the most commonly used commands in Hadoop introduce _php techniques

Suppose the installation directory for Hadoop is hadoop_home to/home/admin/hadoop.
Start and close
Start Hadoop
1. Enter the Hadoop_home directory.
2. Perform SH bin/start-all.sh

Turn off Hadoop
1. Enter the Hadoop_home directory.
2. Perform SH bin/stop-all.sh
File actions
Hadoop uses HDFs, which is similar to the disk system we use. and supports wildcard characters, such as *.

View File List
View the files in the/user/admin/aaron directory in HDFs.
1. Enter the Hadoop_home directory.
2. Perform sh bin/hadoop fs-ls/user/admin/aaron
In this way, we found the files in the/user/admin/aaron directory in HDFs.
We can also list all the files in the/user/admin/aaron directory in HDFs (including the files under subdirectories).
1. Enter the Hadoop_home directory.
2. Perform sh bin/hadoop fs-lsr/user/admin/aaron

Create a file directory
View the/user/admin/aaron directory in HDFs and create a new directory called Newdir.
1. Enter the Hadoop_home directory.
2. Perform sh bin/hadoop fs-mkdir/user/admin/aaron/newdir

deleting files
Delete a file named Needdelete in the/user/admin/aaron directory in HDFs
1. Enter the Hadoop_home directory.
2. Perform sh bin/hadoop fs-rm/user/admin/aaron/needdelete
Delete the/user/admin/aaron directory in HDFs and all files in the directory
1. Enter the Hadoop_home directory.
2. Perform sh bin/hadoop fs-rmr/user/admin/aaron

Uploading files
Upload a native/home/admin/newfile file to the/user/admin/aaron directory in HDFs
1. Enter the Hadoop_home directory.
2. Perform sh bin/hadoop fs–put/home/admin/newfile/user/admin/aaron/

Download files
Download the NewFile file in the/user/admin/aaron directory in HDFs to the native/home/admin/newfile
1. Enter the Hadoop_home directory.
2. Perform sh bin/hadoop fs–get/user/admin/aaron/newfile/home/admin/newfile

View Files
We can directly view the file directly in the HDFs, the function and the class is cat similar
View NewFile files in the/user/admin/aaron directory in HDFs
1. Enter the Hadoop_home directory.
2. Perform sh bin/hadoop fs–cat/home/admin/newfile

MapReduce Job operation
Submit MapReduce Job
In principle, all mapreduce jobs in Hadoop are a jar package.
Run a/home/admin/hadoop/job.jar mapreduce job
1. Enter the Hadoop_home directory.
2. Perform sh bin/hadoop jar/home/admin/hadoop/job.jar [jobmainclass] [Jobargs]

Kill a running job
Suppose job_id is: job_201005310937_0053
1. Enter the Hadoop_home directory.
2. Perform sh bin/hadoop job-kill job_201005310937_0053

More Hadoop commands
The operation commands of these Hadoop are the most commonly used. If you want to learn more, you can get instructions for the command in the following way.
1. Enter the Hadoop_home directory.
2. Perform SH bin/hadoop
We can see more instructions for the command:

Copy Code code as follows:

Usage:hadoop [--config Confdir] COMMAND
Where COMMAND is one of:
Namenode-format Format the DFS filesystem
Secondarynamenode Run the DFS secondary Namenode
Namenode Run the DFS namenode
Datanode Run a DFS datanode
Dfsadmin Run a DFS admin client
Fsck Run a DFS filesystem checking utility
FS Run a generic filesystem user Client
Balancer run a cluster balancing utility
Jobtracker run the MapReduce job Tracker node
Pipes run a pipes job
Tasktracker Run a MapReduce task Tracker node
Job Manipulate MapReduce Jobs
Queue get information regarding Jobqueues
Version Print the version
Jar <jar> Run a jar file
Distcp <srcurl> <desturl> Copy file or directories recursively
Archive-archivename NAME <src>* <dest> Create a Hadoop archive
Daemonlog Get/set The log level for each daemon
Or
CLASSNAME run the class named CLASSNAME
Most commands Print Help when invoked w/o parameters.