We restart LISTSERV on a regular basis (to rotate logs, etc). However, when we do the restart we get

>>> Cannot bind to local host, port 2306: error 48.              
>>> TCP/IP GUI interface disabled <<<                            
9 Nov 2018 10:06:39 LISTSERV(R) for unix version 16.5 starting...
9 Nov 2018 10:06:39  Copyright Eric Thomas 1986-2018
9 Nov 2018 10:06:39 Build date: 17 May 2018
9 Nov 2018 10:06:39
9 Nov 2018 10:06:39 SIGNUP files are being compressed...

in the log and the web interface does not work.

The recommended way to rotate LISTSERV's logs under unix, which does not require stopping and restarting LISTSERV, is found in this section.

The error you are seeing is a function of how you are stopping LISTSERV. LISTSERV normally runs in two or more processes under unix, a parent plus one or more children. If you use 'kill -9' to stop LISTSERV, there is a very good chance that you will not kill all of the children. This error normally occurs because one of the unkilled children is bound to port 2306, the port used by 'wa' to communicate with LISTSERV.

The supported method of stopping LISTSERV is to send LISTSERV a "STOP" command (which must be authenticated with the CREATEPW value) from one of the POSTMASTER= accounts. This can be done either by mail or by using the 'lcmd' utility. This is the only method that is guaranteed to stop LISTSERV properly.

You can also try 'kill -TERM' instead of 'kill -9'. 'kill -TERM' produces (on most systems) a more orderly shutdown. (Since it does not work 100% of the time, it is not a supported solution.)

Note carefully that LISTSERV will not stop until it has finished whatever jobs are ahead of the STOP command in its queue.