ISSUE
How do I run simple Hadoop Distributed File System tasks? Or
How do I test that HDFS services are working?
SOLUTION
Make sure the name node and the data nodes are started.
To start the name node:
su hdfs - -c "hadoop-daemon.sh --config /etc/hadoop/ start namenode"
To start a data node:
su hdfs - -c "hadoop-daemon.sh --config /etc/hadoop start datanode"
Put data files into HDFS. This command will take a file from disk and put into HDFS:
su hdfs hadoop fs -put trial_file.csv /user/hdfs/trial_file.csv
Read data from HDFS. This command will read the contents of a file from HDFS and display on the console:
su hdfs hadoop fs -cat /user/hdfs/trial_file.csv
References:
http://hadoop.apache.org/common/docs/current/file_system_shell.html
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