一、TNS-12547：
TNS-12547: TNS:lost contact
TNS-12560: TNS:protocol adapter error
TNS-00517: Lost contact
Linux Error: 104: Connection reset by peer
发现/etc/hosts中并没有127.0.0.1 localhost.
修改/etc/hosts,修改后如下
$ cat /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost
二、TNS-12555：
TNS-12555: TNS:permission denied
TNS-12560: TNS:protocol adapter error
TNS-00525: Insufficient privilege for operation
Linux Error: 1: Operation not permitted
解决如下：
# chmod 777 /var/tmp/.oracle
原因分析：Oracle卸载不干净，导致/var/tmp/.oracle目录权限不足，故而报错。
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