From: utzoo!decvax!cca!ima!johnl Newsgroups: net.unix-wizards Title: Re: UUCP and line turn around Article-I.D.: ima.187 Posted: Fri Aug 13 10:50:39 1982 Received: Tue Aug 17 07:08:20 1982 References: n44a.111 Dan Ts'o's method of turning around a line for use as both dial in and dial out strikes me as being somewhat overimplemented. Here's how I accomplished it with less work: 1. You have programs "enable" and "disable" that edit /etc/ttys and poke the init process. They have been on Usenix tapes before and are easy to write in any event. 2. Modify /etc/getty so that it deletes /usr/spool/uucp/LCK..ttyX whenever it starts up on line X (because the line is now free.) Have it create that file when a user starts to log in, e.g. when it gets the first character of the login name. You might have a file that identifies lines that are subject to turn-around, to avoid useless lock files. If your version of /etc/init opens the tty before calling getty, you'll have to delete the lock file in init. 3. Modify uucp (and cu if you use it) so that when it creates the lock file it looks in /etc/ttys, and if the line is enabled, it disables it. Similarly, when it deletes the lock file, it should re-enable the line if it previously disabled it. That's all you need to do. Works fine for me. Dan's method avoided changing uucp, but involved changes to the kernel. This method keeps it all in user mode.