Connecting to the CogServer
The CogServer, by default, listens for telnet connections on port 17001. After starting the CogServer, use telnet to connect to it. From from a separate terminal window, run
rlwrap telnet localhost 17001
You should be presented with:
Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. opencog>
Run "help"<enter> to get a list of commands. After additional modules are loaded, additional commands will appear.
Available commands: config: Config a loaded module help: List the available commands; print help for a specific command json: Enter the JSON shell list: List the currently loaded cogserver modules load: Load a cogserver module py: Enter the python shell py-eval: Run a block of python code, and return immediately quit: Close the shell connection scm: Enter the scheme shell sexpr: Enter the s-expression shell shutdown: Shut down the cogserver stats: Print some diagnostic statistics about the server. top: Print server stats continuously unload: Unload an opencog module
To get information about any of the commands, use "help <name of command>". For example
opencog> help scm
Usage: scm [hush|quiet|sync]
Enter the scheme interpreter shell. This shell provides a rich
and easy-to-use environment for creating, deleting and manipulating
OpenCog atoms and truth values. It provides a full R5RS-compliant
interactive scheme shell, based on the GNU Guile extension language.
If 'hush' or 'quiet' is specified after the command, then the prompt
will not be returned. This is nice when catting large scripts using
netcat, as it avoids printing garbage when the scripts work well.
If 'sync' is specified after the command, then the output is sync,
instead of async.
Telnet, UTF-8 and Readline bugs
There are assorted bugs that can bite.
telnet vs UTF-8
Not all versions of telnet are UTF-8 clean. These version will handle many or most UTF-8 strings, but not all. For example, in buggy versions, (Concept "“") will cause a ABORT: decoding-error ... Get out of this with a ctrl-C, and use netcat, instead. The problem is described here, in reddit.
The work-around is to use netcat, which is 8-bit-clean. Like so:
rlwrap nc localhost 17001
This works great, except that sending ctrl-C to the CogServer is now harder: you have to send ctrl-V ctrl-C because a naked ctrl-C will just kill netcat.
rlwrap eats prompts
Some versions of rlwrap eat the prompt. This is described in a rlwrap bug report. This happens on Deian stable, with libreadline8 version 8.1 and rlwrap version 0.43.
There is no known workaround. Just squint your eyes and pretend everything is OK.
