[异常笔记]启动DFS报错：Cannot find configuration directory: /etc/hadoop

[hadoop@master ~]$ start-dfs.sh
Incorrect configuration: namenode address dfs.namenode.servicerpc-address or dfs.namenode.rpc-address is not configured.
Starting namenodes on []
Error: Cannot find configuration directory: /etc/hadoop
Error: Cannot find configuration directory: /etc/hadoop
Starting secondary namenodes [0.0.0.0]
Error: Cannot find configuration directory: /etc/hadoop

[hadoop@master ~]$  vi /opt/software/hadoop-2.7.7/etc/hadoop/hadoop-env.sh

   export HADOOP_CONF_DIR=/opt/software/hadoop-2.7.7/etc/hadoop

[hadoop@master ~]$ source /opt/software/hadoop-2.7.7/etc/hadoop/hadoop-env.sh