CODEWITHSUNDEEP
hadoophadoop2
Vishrant
Vishrant

Reputation: 16628

hadoop -version giving me wrong result why? Hadoop 1.2.1

I executed below command: hadoop -version on hadoop version 1.2.1

vishrant@ubuntu:~$ hadoop -version
java version "1.7.0_79"
OpenJDK Runtime Environment (IcedTea 2.5.5) (7u79-2.5.5-0ubuntu0.12.04.1)
OpenJDK Server VM (build 24.79-b02, mixed mode)

I was expecting hadoop version but I got the version of JDK installed on my system. I know that correct command is hadoop version [without hyphen] but instead of getting error I got the version of JDK why?

Upvotes: 2

Views: 296

Answers (1)

Binary Nerd
Binary Nerd

Reputation: 13927

It looks like the hadoop script for 1.2.x has much less checking than more recent versions, at this point (2016) its about 3 years old. You can see the source for it here.

In the 1.2.x script if you type hadoop -version the script will hit the final else statement where it works out what class to run and sets $CLASS to $COMMAND (line 338) instead of a class.

You can see what it will run on line 434:

exec "$JAVA" -Dproc_$COMMAND $JAVA_HEAP_MAX $HADOOP_OPTS -classpath "$CLASSPATH" $CLASS "$@"

So if you type hadoop version it will run (removed classpath stuff to keep it short):

java -Dproc_version -Xmx1000m -classpath <LIBS> org.apache.hadoop.util.VersionInfo

If you type hadoop -version you get:

java -Dproc_-version -Xmx1000m -classpath <LIBS> -version

So because the default behavior is to set $CLASS to $COMMAND you basically end up with it running:

java -version

Which is what you're getting.

Upvotes: 2

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