在Linux下配置Hadoop出现localhost: Error: JAVA_HOME is not set and could not be found.

Starting namenodes on []

localhost: Error: JAVA_HOME is not set and could not be found.
localhost: Error: JAVA_HOME is not set and could not be found.

...

starting yarn daemons
starting resourcemanager, logging to /home/lihanhui/open-source/hadoop-2.1.0-beta/logs/yarn-admin-resourcemanager-localhost.out
localhost: Error: JAVA_HOME is not set and could not be found.

直接命令行执行export JAVA_HOME=/PATH/TO/JDK无法解决问题

grep命令发现libexec/hadoop-config.sh文件中有错误提示中的黑体字，于是在对应位置前直接设置export JAVA_HOME=/PATH/TO/JDK

错误消失。