Install Java On Ubuntu By CommandLine

Installing JRE/JDK

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sudo apt-get update  # update the package index
java -version  # check if java installed
sudo apt-get install default-jre  # install JRE
sudo apt-get install default-jdk  # install JDK, if necessary

Setting the “JAVA_HOME” environment variable

  1. find out the path of JAVA installation

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    sudo update-alternatives --config java

    It perhaps returns:

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    There is only one alternative in link group java (providing /usr/bin/java): /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java

    Then, the path is “/usr/lib/jvm/java-7-openjdk-amd64”, hold it.

  2. use nano to edit the file /etc/environment

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    sudo nano /etc/environment

    In this file, append the path, holden just now, into the quotes, seperate by colon, like this:

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    JAVA_HOME="your/other/paths:/usr/lib/jvm/java-7-openjdk-amd64"

  3. reload the file /etc/environment

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    source /etc/environment

  4. check if java installed

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    java -version

Finally, it maybe not have to set the environment variable. But I don’t test that.

Reference