TNS-12555: TNS:permission denied

System parameter file is /u2/oracle/10g/network/admin/listener.ora
Log messages written to /u2/oracle/10g/network/log/listener.log
Trace information written to /u2/oracle/10g/network/trace/listener.trc
Trace level is currently 0

Started with pid=23250
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=tiptop)(PORT=1521)))
Error listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC0)))
TNS-12555: TNS:permission denied
 TNS-12560: TNS:protocol adapter error
  TNS-00525: Insufficient privilege for operation
   Linux Error: 1: Operation not permitted
No longer listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=tiptop)(PORT=1521)))

通过日志错误信息可知，应该跟权限有关，最后发现了一个隐藏的信息，
/var/tmp/.oracle这个目录比较特殊,如果oracle没有对此目录的操作权限的话，oracle用户就无法进入/var/tmp/.oracle文件夹.

 方法很简单，以下兩者皆可(建議2)

1.chmod 777 /var/tmp/.oracle 之后就ok了.
2.su 成 root，(或sudo) ，然後 chown -R oracle:oinstall /var/tmp.oracle