Hadoop: «Error:Java_Home Is Not Set»

Error: JAVA_HOME is not set and could not be found after hadoop installation

Let's edit /etc/hadoop/hadoop-env.sh file and set JAVA_HOME for Hadoop. It is the path on which you didn't find hadoop-env.sh.

Open the file and find the line as bellow

export JAVA_HOME=/usr/lib/jvm/jdk-8-oracle-arm32-vfp-hflt/

If the line exists and is commented out, do uncomment. Otherwise, add the line into the file. Beware not

export JAVA_HOME=${JAVA_HOME}

If the file is still not found, maybe path is different. Try to search it using,

find / -iname 'hadoop-env.sh'

Hadoop on Windows - Error JAVA_HOME is incorrectly set.

If your JAVA_HOME path contains spaces, you must use the Windows 8.3 Pathname

Hadoop: JAVA_HOME is not set

Thank you @Chris Shain and @Chris White for your hints. I was running hadoop as su, and su doesn't automatically know about the environmental variables I set. I logged in as my hadoop user (I had chown'd the hadoop install directory to this user), and was able to format the hdfs.

Secondary problem: When I tried to start Hadoop, NameNode and JobTracker started successfully but DataNode, SecondaryNameNode, and TaskTracker failed to start. I dug in a little bit. NameNode and JobTracker are started via hadoop-daemon.sh, but DataNode, SecondaryNameNode, and TaskTracker are started by hadoop-daemon*s*.sh. The resolution here was to properly set JAVA_HOME in conf/hadoop-env.sh.

run hadoop ERROR: JAVA_HOME /usr/bin/java does not exist

/usr/bin/java is not a java home. A java home must be a folder (not a program) with a bin directory which contains java, jps, maybe javac and so on. You must find your jre or jdk folder and set it as JAVA_HOME.

get ll /usr/bin/java and it may be a symbolic link to your Java path. or do find /usr/lib/jvm/java-1.x.x-openjdk to find your java home. The parent directory of Java program is your JAVA_HOME and must be set with export in hadoop-env.sh.

getting JAVA_HOME is incorrectly set with hadoop

Your JAVA_HOME should not include bin. Change it from

"C:\Program Files\Java\jdk1.8.0_45\bin"

to

"C:\Program Files\Java\jdk1.8.0_45"

And you can add it to your path (in Windows) like

set "PATH=%PATH%;%JAVA_HOME%\bin"

JAVA_HOME is set incorrectly -- Hadoop on Windows 10

JAVA_HOME should be point to the root directory of a Java JDK and should be specified in the environment variables. After setting this value a restart of the terminal/application/console/IDE/command-prompt is required to make the new value active.

If you simple give: java --version it use the first java.exe version found on your PATH. JAVA_HOME and the PATH java version don't have any relation with each other.

JAVA_HOME can be specified for example to: "c:/java/jdk9" and your path includes "c:/java/jdk8/bin". In this situation java --version will give you 1.8.x.x.

JAVA_HOME is used by processes that forks to a new subproces and then used that JAVA_HOME value.

In your situation there is probably only a spacer missing in/after the call to hadoop-env.cmd ?? (not clear with the current info)

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