Hadoop command

--Merge files

cat * > merged-file

hadoop com.sun.tools.javac.Main PearsonCorrelation.java
jar cf PearsonCorrelation.jar PearsonCorrelation*.class
hadoop jar PearsonCorrelation.jar PearsonCorrelation

--multiful files

export HADOOP_CLASSPATH=$JAVA_HOME/lib/tools.jar

-compile
hadoop com.sun.tools.javac.Main SmallFilesToSequenceFile.java FullFileRecordReader.java FullFileInputFormat.java
hadoop com.sun.tools.javac.Main *.java

-create jar
jar cf sfts.jar SmallFilesToSequenceFile*.class FullFile*.class
jar cf ISMR.jar ImageSimlarityMapReduce.class SimilaritySearchWithLIRE*.class WholeFileInputFormat*.class
jar cf ISMR.jar ImageSimlarityMapReduce.class SimilaritySearchWithLIRE.class WholeFileInputFormat.class WholeFileRecordReader.class
jar cf wc.jar *.class

-execute
hadoop jar sfts.jar SmallFilesToSequenceFile /user/unlv/sheep1/image /user/unlv/sheep1/aggimage1
hadoop jar imageSimlarityMapReduce.jar imageSimlarityMapReduce /home/unlv/workspace/imageProject/data/image/14985/129475963886.jpg
hadoop jar ImageSimlarityMapReduce.jar ImageSimlarityMapReduce 130054312049.jpg /user/unlv/sheep1/aggimage1 /user/unlv/sheep1/output/istest1

-count:
hdfs dfs -count /user/unlv/sheep1/image
-make directory
hdfs dfs -mkdir -p /user/unlv/sheep1/image/

-input multi file
hdfs dfs -put 1507*/* /user/unlv/sheep1/image/
java -jar ImageSimlarityMapReduce.jar /home/unlv/workspace/imageProject/data/image/14985/129475963886.jpg -XX:-UseGCOverheadLimit

-change replication
hadoop dfs -setrep -w 4 /path/to/file
use this command to find out the location of file, find #rack it is stored, what is the block name on all racks
hadoop fsck /path/to/your/directory -files -blocks -locations -racks