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Rio manages asynchronous layers of text, or windows, on a raster
display. It also serves a variety of files for communicating with
and controlling windows; these are discussed in section rio(4).
Commands
The rio command starts a new instance of the window system. Its
–i option names a startup script, which typically contains several
window commands generated by wloc. The –k option causes rio to
run the command kbdcmd at startup and allow it to provide characters
as keyboard input; the keyboard program
described in bitsyload(1) is the usual choice.
The –s option initializes windows so that text scrolls; the default
is not to scroll. The font argument names a font used to display
text, both in rio's menus and as a default for any programs running
in its windows; it also establishes the environment variable $font.
If –f is not given, rio uses the imported value of
$font if set; otherwise it imports the default font from the underlying
graphics server, usually the terminal's operating system.
The label command changes a window's identifying name.
The window command creates a window. By default, it creates a
shell window and sizes and places it automatically. The geometry
arguments control the size (dx, dy) and placement (minx, miny,
maxx, maxy); the units are pixels with the upper left corner of
the screen at (0, 0). The hide option causes the window
to be created off–screen. The scroll and noscroll options set the
scroll mode. The cd option sets the working directory. The optional
command and arguments define which program to run in the window.
By default, window uses /dev/wctl (see rio(4)) to create the window
and run the command. Therefore, the window and command will be
created by rio and run in a new file name space, just as if the
window had been created using the interactive menu. However, the
–m option uses the file server properties of rio to
mount (see bind(1)) the new window's name space within the name
space of the program calling window. This means, for example,
that running window in a CPU window will create another window
whose command runs on the terminal, where rio is running; while
window –m will create another window whose
command runs on the CPU server.
The wloc command prints the coordinates and label of each window
in its instance of rio and is used to construct arguments for
window.
Window control
Each window behaves as a separate terminal with at least one process
associated with it. When a window is created, a new process (usually
a shell; see rc(1)) is established and bound to the window as
a new process group. Initially, each window acts as a simple terminal
that displays character text; the standard input
and output of its processes are attached to /dev/cons. Other special
files, accessible to the processes running in a window, may be
used to make the window a more general display. Some of these
are mentioned here; the complete set is discussed in rio(4).
One window is current, and is indicated with a dark border and
text; characters typed on the keyboard are available in the /dev/cons
file of the process in the current window. Characters written
on /dev/cons appear asynchronously in the associated window whether
or not the window is current.
Windows are created, deleted and rearranged using the mouse. Clicking
(pressing and releasing) mouse button 1 in a non–current window
makes that window current and brings it in front of any windows
that happen to be overlapping it. When the mouse cursor points
to the background area or is in a window that has
not claimed the mouse for its own use, pressing mouse button 3
activates a menu of window operations provided by rio. Releasing
button 3 then selects an operation. At this point, a gunsight
or cross cursor indicates that an operation is pending. The button
3 menu operations are:
New Create a window. Press button 3 where one corner of the new
rectangle should appear (cross cursor), and move the mouse, while
holding down button 3, to the diagonally opposite corner. Releasing
button 3 creates the window, and makes it current. Very small
windows may not be created.
Resize Change the size and location of a window. First click button
3 in the window to be changed (gunsight cursor). Then sweep out
a window as for the New operation. The window is made current.
Move Move a window to another location. After pressing and holding
button 3 over the window to be moved (gunsight cursor), indicate
the new position by dragging the rectangle to the new location.
The window is made current. Windows may be moved partially off–screen.
Delete Delete a window. Click in the window to be deleted (gunsight
cursor). Deleting a window causes a hangup note to be sent to
all processes in the window's process group (see notify(2)).
Hide Hide a window. Click in the window to be hidden (gunsight
cursor); it will be moved off–screen. Each hidden window is given
a menu entry in the button 3 menu according to the value of the
file /dev/label, which rio maintains (see rio(4)).
label Restore a hidden window.
Windows may also be arranged by dragging their borders. Pressing
button 1 or 2 over a window's border allows one to move the corresponding
edge or corner, while button 3 moves the whole window.
Text windows
Characters typed on the keyboard or written to /dev/cons collect
in the window to form a long, continuous document.
There is always some selected text, a contiguous string marked
on the screen by reversing its color. If the selected text is
a null string, it is indicated by a hairline cursor between two
characters. The selected text may be edited by mousing and typing.
Text is selected by pointing and clicking button 1 to make a null–
string selection, or by pointing, then sweeping with button 1
pressed. Text may also be selected by double–clicking: just inside
a matched delimiter–pair with one of {[(<«`'" on the left and }])>»`'"
on the right, it selects all text within the pair; at the beginning
or end of a line, it selects the line; within or at the
edge of an alphanumeric word, it selects the word.
Characters typed on the keyboard replace the selected text; if
this text is not empty, it is placed in a snarf buffer common
to all windows but distinct from that of sam(1).
Programs access the text in the window at a single point maintained
automatically by rio. The output point is the location in the
text where the next character written by a program to /dev/cons
will appear; afterwards, the output point is the null string beyond
the new character. The output point is also the location
in the text of the next character that will be read (directly
from the text in the window, not from an intervening buffer) by
a program from /dev/cons. When such a read will occur is, however,
under control of rio and the user.
In general there is text in the window after the output point,
usually placed there by typing but occasionally by the editing
operations described below. A pending read of /dev/cons will block
until the text after the output point contains a newline, whereupon
the read may acquire the text, up to and including the
newline. After the read, as described above, the output point
will be at the beginning of the next line of text. In normal circumstances,
therefore, typed text is delivered to programs a line at a time.
Changes made by typing or editing before the text is read will
not be seen by the program reading it. If the program in
the window does not read the terminal, for example if it is a
long–running computation, there may accumulate multiple lines of
text after the output point; changes made to all this text will
be seen when the text is eventually read. This means, for example,
that one may edit out newlines in unread text to forestall the
associated text being read when the program finishes computing.
This behavior is very different from most systems.
Even when there are newlines in the output text, rio will not
honor reads if the window is in hold mode, which is indicated
by a white cursor and blue text and border. The ESC character
toggles hold mode. Some programs, such as mail(1), automatically
turn on hold mode to simplify the editing of multi–line text; type
ESC when done to allow mail to read the text.
An EOT character (control–D) behaves exactly like newline except
that it is not delivered to a program when read. Thus on an empty
line an EOT serves to deliver an end–of–file indication: the read
will return zero characters. Like newlines, unread EOTs may be
successfully edited out of the text. The BS character
(control–H) erases the character before the selected text. The
ETB character (control–W) erases any nonalphanumeric characters,
then the alphanumeric word just before the selected text. `Alphanumeric'
here means non–blanks and non–punctuation. The NAK character (control–U)
erases the text after the output point,
and not yet read by a program, but not more than one line. All
these characters are typed on the keyboard and hence replace the
selected text; for example, typing a BS with a word selected places
the word in the snarf buffer, removes it from the screen, and
erases the character before the word.
An ACK character (control–F) or Insert character triggers file
name completion for the preceding string (see complete(2)).
Typing a left or right arrow moves the cursor one character in
that direction. Typing an SOH character (control–A) moves the cursor
to the beginning of the current line; an ENQ character (control–E)
moves to the end.
Text may be moved vertically within the window. A scroll bar on
the left of the window shows in its clear portion what fragment
of the total output text is visible on the screen, and in its
gray part what is above or below view; it measures characters,
not lines. Mousing inside the scroll bar moves text: clicking
button 1
with the mouse pointing inside the scroll bar brings the line
at the top of the window to the cursor's vertical location; button
3 takes the line at the cursor to the top of the window; button
2, treating the scroll bar as a ruler, jumps to the indicated
portion of the stored text. Holding a button pressed in the scroll
bar will
cause the text to scroll continuously until the button is released.
Also, a page down or down–arrow scrolls forward half a window,
and page up or up–arrow scrolls back. Typing the home key scrolls
to the top of the window; typing the end key scrolls to the bottom.
The DEL character sends an interrupt note to all processes in
the window's process group. Unlike the other characters, the DEL,
VIEW, and up– and down–arrow keys do not affect the selected text.
The left (right) arrow key moves the selection to one character
before (after) the current selection.
Normally, written output to a window blocks when the text reaches
the end of the screen; a button 2 menu item toggles scrolling.
Other editing operations are selected from a menu on button 2.
The cut operation deletes the selected text from the screen and
puts it in the snarf buffer; snarf copies the selected text to
the buffer without deleting it; paste replaces the selected text
with the contents of the buffer; and send copies the snarf
buffer to just after the output point, adding a final newline
if missing. Paste will sometimes and send will always place text
after the output point; the text so placed will behave exactly
as described above. Therefore when pasting text containing newlines
after the output point, it may be prudent to turn on hold
mode first.
The plumb menu item sends the contents of the selection (not the
snarf buffer) to the plumber(4). If the selection is empty, it
sends the white–space–delimited text containing the selection (typing
cursor). A typical use of this feature is to tell the editor to
find the source of an error by plumbing the file and line
information in a compiler's diagnostic.
Raw text windows
Opening or manipulating certain files served by rio suppresses
some of the services supplied to ordinary text windows. While
the file /dev/mouse is open, any mouse operations are the responsibility
of another program running in the window. Thus, rio refrains from
maintaining the scroll bar, supplying text editing
or menus, interpreting the VIEW key as a request to scroll, and
also turns scrolling on.
The file /dev/consctl controls interpretation of keyboard input.
In particular, a raw mode may be set: in a raw–input window, no
typed keyboard characters are special, they are not echoed to
the screen, and all are passed to a program immediately upon reading,
instead of being gathered into lines.
Graphics windows
A program that holds /dev/mouse and /dev/consctl open after putting
the console in raw mode has complete control of the window: it
interprets all mouse events, gets all keyboard characters, and
determines what appears on the screen.
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