Today tested before until yesterday to build the spark environment. Results expected. The most important reason is the content to be carried out do not understand. Second reason is that not find the right resources. So now, under the command linux all out ineffective. The reason is a change in the environment variable, wrong word (no specific record-keeping). In short lesson is that when configuring the environment, they should be careful. source / etc / profile source ~ / .bashrc sure the best performing it.
If the failure of all the commands, you can refer https://blog.csdn.net/lzb_lxj/article/details/82021571 , enter the configuration file.
mvn -v command error:
错误显示：$mvn -version
The JAVA_HOME environment variable is not defined correctly
This environment variable is needed to run this program
NB: JAVA_HOME should point to a JDK not a JRE
参考：https://blog.csdn.net/weixin_44892849/article/details/89313990 解决
There is also the bloggers say, the proposed permanent modification method when configuring scala, spark and other environmental variables (already practice), can be adopted.