Java runtimes include webstart functionality out of the box. If you have java 8+, just run
javaws [run-options] <jnlp-file> -OR-
javaws [control-options]
Run Options include:
-verbose, -offline, -system (using sys cache), -Xnosplash,
-J<option> (passes options to the virtual machine), -wait
Control Options include:
-viewer, -clearcache, -uninstall, -uninstall <jnlp-file> (more specific),
-import [import-options]
[import-options] includes:
-silent, -system, -codebase <url>, -shortcut, -association