How to run LO headless on Centos 7. There is no libreoffice-headless package?

Errors from java:

2017-01-23 09:53:10,992 ERROR [STDERR] sty 23, 2017 9:53:10 AM org.artofsolving.jodconverter.office.ProcessPoolOfficeManager
INFO: ProcessManager implementation is LinuxProcessManager
2017-01-23 09:53:11,021 ERROR [STDERR] org.artofsolving.jodconverter.office.OfficeException: failed to start and connect
2017-01-23 09:53:11,021 ERROR [STDERR] at org.artofsolving.jodconverter.office.ManagedOfficeProcess.startAndWait(ManagedOfficeProcess.java:64)
2017-01-23 09:53:11,021 ERROR [STDERR] at org.artofsolving.jodconverter.office.PooledOfficeManager.start(PooledOfficeManager.java:101)
2017-01-23 09:53:11,021 ERROR [STDERR] at org.artofsolving.jodconverter.office.ProcessPoolOfficeManager.start(ProcessPoolOfficeManager.java:62)

2017-01-23 09:53:11,026 ERROR [STDERR] Caused by: java.util.concurrent.ExecutionException: org.artofsolving.jodconverter.office.OfficeException: could not establish connection
2017-01-23 09:53:11,026 ERROR [STDERR] at java.util.concurrent.FutureTask.report(FutureTask.java:122)
2017-01-23 09:53:11,026 ERROR [STDERR] at java.util.concurrent.FutureTask.get(FutureTask.java:188)
2017-01-23 09:53:11,026 ERROR [STDERR] at org.artofsolving.jodconverter.office.ManagedOfficeProcess.startAndWait(ManagedOfficeProcess.java:62)
2017-01-23 09:53:11,026 ERROR [STDERR] … 138 more
2017-01-23 09:53:11,026 ERROR [STDERR] Caused by: org.artofsolving.jodconverter.office.OfficeException: could not establish connection
2017-01-23 09:53:11,026 ERROR [STDERR] at org.artofsolving.jodconverter.office.ManagedOfficeProcess.doStartProcessAndConnect(ManagedOfficeProcess.java:142)
2017-01-23 09:53:11,026 ERROR [STDERR] at org.artofsolving.jodconverter.office.ManagedOfficeProcess.access$000(ManagedOfficeProcess.java:31)
2017-01-23 09:53:11,027 ERROR [STDERR] at org.artofsolving.jodconverter.office.ManagedOfficeProcess$1.run(ManagedOfficeProcess.java:58)
2017-01-23 09:53:11,027 ERROR [STDERR] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
2017-01-23 09:53:11,027 ERROR [STDERR] at java.util.concurrent.FutureTask.run(FutureTask.java:262)
2017-01-23 09:53:11,027 ERROR [STDERR] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
2017-01-23 09:53:11,027 ERROR [STDERR] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
2017-01-23 09:53:11,027 ERROR [STDERR] … 1 more
2017-01-23 09:53:11,027 ERROR [STDERR] Caused by: java.lang.IllegalStateException: a process with acceptString ‘socket,host=127.0.0.1,port=2002’ is already running; pid 7008
2017-01-23 09:53:11,027 ERROR [STDERR] at org.artofsolving.jodconverter.office.OfficeProcess.start(OfficeProcess.java:68)
2017-01-23 09:53:11,027 ERROR [STDERR] at org.artofsolving.jodconverter.office.OfficeProcess.start(OfficeProcess.java:61)
2017-01-23 09:53:11,027 ERROR [STDERR] at org.artofsolving.jodconverter.office.ManagedOfficeProcess.doStartProcessAndConnect(ManagedOfficeProcess.java:119)
2017-01-23 09:53:11,027 ERROR [STDERR] … 7 more

You can use Xvfb or vnc to launch a minimal X server to launch calc invisible. I don’t know about a direct method to do it without x. But others may know.

Now I’m looking at help. Seems like you can set system properties of jvm. You could try:

-Djava.awt.headless=true