Usage: jcmd <pid | main class> <command ...|PerfCounter.print|-f file>

   or: jcmd -l                                                       

   or: jcmd -h                                                       

  command must be a valid jcmd command for the selected jvm.    

  Use the command "help" to see which commands are available.   

  If the pid is 0, commands will be sent to all Java processes.   

  The main class argument will be used to match (either partially 

  or fully) the class used to start Java.                         

  If no options are given, lists Java processes (same as -p).     

  PerfCounter.print display the counters exposed by this process   

  -f  read and execute commands from the file                     

  -l  list JVM processes on the local machine                     

  -h  this help