ubuntu寻找jdk目录

echo $JAVA_HOME

which java
whereis java

ls -lrt /usr/bin/java
# /usr/bin/java -> /etc/alternatives/java

ls -lrt /etc/alternatives/java
# /etc/alternatives/java -> /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java

ls -lrt /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java
#  /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java

vim /etc/profile

export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib
export PATH=${JAVA_HOME}/bin:$PATH

source /etc/profile

cat $JAVA_HOME
# cat: /usr/lib/jvm/java-8-openjdk-amd64: Is a directory