To handle permission, scm uses tmp folder. The scm is an alternative library to rxtx/javaxcom.
Wiki : http://www.embeddedunveiled.com/
Repository : https://github.com/RishiGupta12/serial-communication-manager
Video : https://www.youtube.com/watch?v=fYLQbelGunQ
It supports RS-232 control signals handshaking, monitoring and has been ported to Linux, MAC, Solaris and Windows operating system. It is consistent, portable, efficient, reliable, testable, extensible, modifiable, scalable library.