Start RZ agent will change the permission of /dev/null from 666 to 660.
The RZ was installed by root user and the permission of /dev/null was 666. When start RZ agent with root, the permission of /dev/null will be changed to 660.
Oracle API will change the permission of /dev/null if agent was started by root.
Tivoli Monitoring Agent for Oracle Database Extended li6263 Version: 06.31.01.00
Resolving the problem
Re-install/configure/start RZ agent with "oracle" user.
1. Create an install directory for RZ agent, such as "/opt/oracle_agent/".
2. Change owner of the install directory as below:
chown -R oracle:dba /opt/oracle_agent/
3. Install RZ agent with oracle user in "/opt/oracle_agent/"
4. Configure RZ agent with "oracle" user.
5. Start RZ agent with "oracle" user.