central is the server for the IPC (Inter Process Communications) package developed by Reid Simmons. IPC provides a simple means of communicating between applications on the same computer and other machines via TCP/IP. Central is used by the msb-server and several other applications to share information. More information about IPC can be found at the projects homepage.
Spawn central and send it to the background
central -u &
Note, that only 1 copy of central can be run at one time. If you want to run multiple central's (see the -p argument below) or access central running on another machine you will need to export the CENTRALHOST variable: <bash># If you want to use another port export CENTRALHOST=localhost:1234
- If you want to connect to another machine
export CENTRALHOST=othermachine </bash>
Various debugging/logging capabilities are also available if necessary. Remember to have a process cat the .log file that central creates.
The following are central commands: help: print this message display: display the active and pending messages status: display the known modules and their status memory: display total memory usage close <module>: close a connection to a module unlock <resource>: unlock a locked resource The following command line options can also be used as commands: -v: display server version information -l<option>: logging onto terminal. Options are: m (message traffic) s (status of IPC) t (time messages are received by central) d (data associated with messages) i (ignore logging certain internal messages) h (handle time summary of incoming messages) r (log the reference ID as well as the message name) p (log the reference ID of the message’s parent) x (no logging) -l (no options) is equivalent to -lmstdh; the default is –lmsi -L<option>: logging into file. Options are the same as above, with the addition of F (don’t flush file after each line) n (don’t prompt user for comments) The default is –Lx -f<filename>: filename to use for logging; If not specified, name is automatically generated. -p<port>: connect to central server on this port number. -c: Use direct (not via central) connections when possible -I<msgName>: Ignore logging this message (can occur multiple times). -I<filename>: File with names of messages to ignore logging -s: silent running; don’t print anything to terminal. -u: don’t run the user (tty) interface. -r: try resending non-completed messages when modules crash and then reconnect.
central typically does not output anything to the console unless an error occurs.