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MUX(9.1) MUX(9.1) NAME mux, ismux, invert - layer multiplexer for 5620 SYNOPSIS mux [ -l command ... ] mux exit mux cd directory ismux [ - ] invert DESCRIPTION Mux manages asynchronous windows, or layers. Upon invocation, it loads the terminal with a program (default settable by the environment vari- able MUXTERM) that is the primary user interface. Option -l also cre- ates a layer and invokes the shell to run commands in it. (See win- dows(9.1)). The command leaves mux, destroying all layers; changes the directory of mux, and hence of layers later created, but not of the current layers. Each layer is essentially a separate terminal. Characters typed into the layer are sent to the standard input of a Unix process bound to the layer, and characters written on the standard output of that process appear in the layer. When a layer is created, a separate shell (the value of the SHELL environment variable, or sh by default) is estab- lished, and bound to the layer. Layers are created, deleted, and rearranged using the mouse. Depress- ing mouse button 3 activates a menu of layer operations. Releasing button 3 then selects an operation. At this point, a gunsight or box cursor indicates that an operation is pending. Hitting button 3 again activates the operation on the layer pointed to by the cursor. The New operation, to create a layer, requires a rectangle to be swept out, across any diagonal, while button 3 is depressed. A box outline cursor indicates that a rectangle is to be created. The Reshape opera- tion, to change the size and location of a layer on the screen, re- quires first that a layer be indicated (gunsight cursor) and a new rec- tangle be swept out (box cursor). The other operations are self-ex- planatory. In a non-current layer, button 1 is a shorthand for Top and Current, which pulls a layer to the front of the screen and makes it the active layer for keyboard and mouse input. Th current layer is indicated by a heavy border. There is a point in each layer, called the `Unix point', where the next character from the host Unix system will be inserted. The Unix point advances whenever characters are received from the host, but not when echoing typed characters. When a newline is typed after the Unix point, characters between the Unix point and the newline, inclusive, are sent to the host and the Unix point advanced to after the newline. This means that shell prompts and other output will be inserted before characters that have been typed ahead. No other characters are sent to the host (but see the discussion of raw mode below). Therefore par- tially typed lines or text anywhere before the Unix point may be edited. The default terminal program allows any text on the screen to be edited, much as in sam(9.1). Text may be selected by sweeping it with button 1 depressed. Typed characters replace selected text. All layers share a common `snarf buffer' (distinct from sam's). The cut operation on button 2 deletes selected text and puts it in the buffer; snarf copies selected text to the buffer; paste replaces se- lected text (which may be null) from the buffer; and send copies the snarf buffer to after the Unix point. Normally the terminal doesn't scroll as text is received, but a button 2 menu item selects scrolling. A scroll bar indicates what portion of all the text stored for a layer is on the screen. (It measures characters, not lines.) Releasing but- ton 1 in the scroll bar brings the line at the top of the screen to the cursor; releasing button 3 takes the line at the cursor to the top of the screen. Button 2, treating the scroll bar as a ruler, brings the indicated point in the whole stored text to the top of the screen. Slide the cursor off either end of the scroll bar with button 2 de- pressed to get right to an end of the file. The NUM LOCK key advances a half page. Ismux reports on its standard error whether its standard output is a mux layer, and also generates the appropriate exit status. With option no message is produced. Invert reverses the sense of video, from black on white to white on black, or vice versa. Independent user-level programs can be loaded into layers, see 32ld(9.1). SHIFT-SETUP freezes mux and complements the video of the layer of the running user-level terminal process. Hitting button 2 in this state will attempt to kill the process; 1 or 3 will leave it run- ning. In raw mode or no-echo mode (see ttyld(4)) the Unix point advances with each character typed after it. In 8bit mode, characters with octal codes 0200 and greater print according to the ISO Latin1 alphabet; see ascii(6). FILES temporary file used by -l option SEE ALSO 32ld(9.1), sam(9.1), jx(9.1), term(9.1), windows(9.1) R. Pike, `Blit Download Protocols', this manual, Vol. 2 DIAGNOSTICS Mux refuses to create a layer when there is not enough memory. Space can be recovered by deleting a layer. Error messages from mux are written directly to the layer which caused them. They are usually meaningful only to system administrators, and indicate system difficulties. BUGS Reshape only works properly for processes that arrange to see if they have been reshaped, although most programs make this arrangement. The behavior of raw mode prohibits editing partially typed lines when running cu(1). MUX(9.1)