jr@LF-SERVER-2.BBN.COM (John Robinson) (11/30/87)
Following is an attempt at a brief note to explain how to cope with flow control in GNU Emacs. I plan to keep this around to send to users who ask (frequently) "how to I get Emacs to do flow control?" I solicit your comments/additions/etc. /jr jr@bbn.com or jr@bbn.uucp -------- GNU emacs (version 18.48 and later) provides several options for coping with terminals or front-ends that insist on using flow control characters. Listed in estimated order of preference. 1. Have Emacs run in CBREAK mode with the kernel handling flow control. Issue (set-input-mode nil t) from .emacs. It is now necessary to find other keys to bind to the commands isearch-forward and quoted-insert. Traditional nominees are C-^ and C-\. There are two ways to get this effect: 1a. Use the keyboard-translate-table to cause C-^ and C-\ to be received by Emacs as though C-S and C-Q were typed. Emacs (except at its very lowest level) never knows that the characters typed were anything but C-S and C-Q, so the use of these keys inside isearch still works - typing C-^ while incremental searching will move the cursor to the next match, etc. 1b. Simply rebind the keys C-^ and C-\ to isearch-forward and quoted-insert. To get continued searches inside isearch it is also necessary to set search-repeat-char to C-^. 2. Don't use CBREAK mode, and global-unset-key the keys C-S and C-Q. The problem with this is that whatever sent the flow control characters is apt to be falling behind the characters being sent to it, and so what finds its way to the terminal screen will not in general be what is intended. It will be still be necessary to find other keys to bind to isearch-forward and quoted-insert; see 1a and 1b above. Note that, if the terminal is the source of flow control characters and kernel flow control handling is enabled, it will not in general be necessary to send padding characters as specified in a termcap or terminfo entry. It may be possible to customize a termcap entry to provide better Emacs performance on the assumption that flow control is in use. This effect can also be simulated by announcing (with stty(1) or its equivalent) that the terminal is running at a very slow speed, provided the terminal is not directly wired to the host.