[lib config] #linux
### java config
- Use `java -XshowSettings:properties` to show the java.library.path (and others) value.
### native lib config
- `/lib` contain "essential" libraries that may be needed even in single-user (admin-only) mode and without /usr mounted
- `/usr/lib` are the libraries for the normal user-programs, that mostly can be found under /usr.
- `/usr/local/lib` are the libraries for locally installed programs and packages ie. things you've compiled and installed from source-packages yourself.