window - window environment
window [-t] [-f] [-d] [-e escape-char] [-c command]
window implements a window environment on ASCII terminals.
A window is a rectangular portion of the physical terminal
screen associated
with a set of processes. Its size and position can be
changed by
the user at any time. Processes communicate with their window in the
same way they normally interact with a terminal - through
their standard
input, output, and diagnostic file descriptors. The window
program handles
the details of redirecting input and output to and from
the windows.
At any one time, only one window can receive input from the
keyboard, but
all windows can simultaneously send output to the display.
When window starts up, the commands (see long commands below) contained
in the file .windowrc in the user's home directory are executed. If it
does not exist, two equal sized windows spanning the terminal screen are
created by default.
The options are as follows:
-t Turn on terse mode (see the terse command below).
-f Fast. Don't perform any startup action.
-d Ignore .windowrc and create the two default windows
instead.
-e escape-char
Set the escape character to escape-char.
escape-char can be a
single character, or in the form ^X where X is any
character,
meaning control-X.
-c command
Execute the string command as a long command (see
below) before
doing anything else.
Windows can overlap and are framed as necessary. Each window is named by
one of the digits 1-9. This one-character identifier, as
well as a user
definable label string, are displayed with the window on the
top edge of
its frame. A window can be designated to be in the
foreground, in which
case it will always be on top of all normal, non-foreground
windows, and
can be covered only by other foreground windows. A window
need not be
completely within the edges of the terminal screen. Thus a
large window
(possibly larger than the screen) may be positioned to show
only a portion
of its full size.
Each window has a cursor and a set of control functions.
Most intelligent
terminal operations such as line and character deletion
and insertion
are supported. Display modes such as underlining and
reverse video
are available if they are supported by the terminal. In addition, similar
to terminals with multiple pages of memory, each window
has a text
buffer which can have more lines than the window itself.
Process Environment [Toc] [Back]
With each newly created window, a shell program is spawned
with its process
environment tailored to that window. Its standard input, output,
and diagnostic file descriptors are bound to one end of either a pseudoterminal
(pty(4)) or a UNIX domain socket (socketpair(2)).
If a pseudoterminal
is used, then its special characters and modes (see
stty(1)) are
copied from the physical terminal. A termcap(5) entry tailored to this
window is created and passed as environment (environ(7))
variable
TERMCAP. The termcap entry contains the window's size and
characteristics
as well as information from the physical terminal, such
as the existence
of underline, reverse video, and other display modes,
and the codes
produced by the terminal's function keys, if any. In addition, the window
size attributes of the pseudo-terminal are set to reflect the size of
this window, and updated whenever it is changed by the user.
In particular,
the editor vi(1) uses this information to redraw its
display.
Operation [Toc] [Back]
During normal execution, window can be in one of two states:
conversation
mode and command mode. In conversation mode, the terminal's
real cursor
is placed at the cursor position of a particular window--called the current
window--and input from the keyboard is sent to the process in that
window. The current window is always on top of all other
windows, except
those in the foreground. In addition, it is set apart by
highlighting
its identifier and label in reverse video.
Typing window's escape character (normally ^P) in conversation mode
switches it into command mode. In command mode, the top
line of the terminal
screen becomes the command prompt window, and window
interprets input
from the keyboard as commands to manipulate windows.
There are two types of commands: short commands are usually
one or two
key strokes; long commands are strings either typed by the
user in the
command window (see the ``:'' command below), or read from a
file (see
source below).
Short Commands [Toc] [Back]
Below, # represents one of the digits 1-9 corresponding to
the windows 1
to 9. ^X means control-X, where X is any character. In
particular, ^^
is control-^. Escape is the escape key, or ^[.
# Select window # as the current window and return to
conversation
mode.
%# Select window # but stay in command mode.
^^ Select the previous window and return to conversation mode. This
is useful for toggling between two windows.
escape Return to conversation mode.
^P Return to conversation mode and write ^P to the current window.
Thus, typing two ^P's in conversation mode sends one
to the current
window. If the window escape is changed to
some other character,
that character takes the place of ^P here.
? List a short summary of commands.
^L Refresh the screen.
q Exit window. Confirmation is requested.
^Z Suspend window.
w Create a new window. The user is prompted for the
positions of
the upper left and lower right corners of the window. The cursor
is placed on the screen and the keys `h', `j', `k',
and `l' move
the cursor left, down, up, and right, respectively.
The keys
`H', `J', `K', and `L' move the cursor to the respective limits
of the screen. Typing a number before the movement
keys repeats
the movement that number of times. Return enters
the cursor position
as the upper left corner of the window. The
lower right
corner is entered in the same manner. During this
process, the
placement of the new window is indicated by a rectangular box
drawn on the screen, corresponding to where the new
window will
be framed. Typing escape at any point cancels this
command.
This window becomes the current window, and is given
the first
available ID. The default buffer size is used (see
the
default_nline command below).
Only fully visible windows can be created this way.
c# Close window #. The process in the window is sent
the hangup
signal (see kill(1)). csh(1) should handle this
signal correctly
and cause no problems.
m# Move window # to another location. A box in the
shape of the
window is drawn on the screen to indicate the new
position of the
window, and the same keys as those for the w command
are used to
position the box. The window can be moved partially
off-screen.
M# Move window # to its previous position.
s# Change the size of window #. The user is prompted
to enter the
new lower right corner of the window. A box is
drawn to indicate
the new window size. The same keys used in w and m
are used to
enter the position.
S# Change window # to its previous size.
^Y Scroll the current window up by one line.
^E Scroll the current window down by one line.
^U Scroll the current window up by half the window
size.
^D Scroll the current window down by half the window
size.
^B Scroll the current window up by the full window
size.
^F Scroll the current window down by the full window
size.
h Move the cursor of the current window left by one
column.
j Move the cursor of the current window down by one
line.
k Move the cursor of the current window up by one
line.
l Move the cursor of the current window right by one
column.
y Yank. The user is prompted to enter two points
within the current
window. Then the content of the current window
between
those two points is saved in the yank buffer.
p Put. The content of the yank buffer is written to
the current
window as input.
^S Stop output in the current window.
^Q Start output in the current window.
: Enter a line to be executed as long commands. Normal line editing
characters (erase character, erase word, erase
line) are supported.
Long Commands [Toc] [Back]
Long commands are a sequence of statements parsed much like
a programming
language, with a syntax similar to that of C. Numeric and
string expressions
and variables are supported, as well as conditional
statements.
There are two data types: string and number. A string is a
sequence of
letters or digits beginning with a letter. `_' and `.' are
considered
letters. Alternately, non-alphanumeric characters can be
included in
strings by quoting them in `"' or escaping them with `'. In
addition,
the `' sequences of C are supported, both inside and outside
quotes ' a carriage return). For example,
(e.g., `0 is a newline, `
these
are legal strings: abcde01234, "&#$^*&#", ab"$#"cd, ab
"/usr/ucb/window".
A number is an integer value in one of three forms: a decimal number, an
octal number preceded by `0', or a hexadecimal number preceded by `0x' or
`0X'. The natural machine integer size is used (i.e., the
signed integer
type of the C compiler). As in C, a non-zero number represents a boolean
true.
The character `#' begins a comment which terminates at the
end of the
line.
A statement is either a conditional or an expression. Expression statements
are terminated with a new line or `;'. To continue an
expression
on the next line, terminate the first line with `'.
Conditional Statement [Toc] [Back]
window has a single control structure: the fully bracketed
if statement
in the form
if <expr> then
<statement>
...
elsif <expr> then
<statement>
...
else
<statement>
...
endif
The else and elsif parts are optional, and the latter can be
repeated any
number of times. <Expr> must be numeric.
Expressions [Toc] [Back]
Expressions in window are similar to those in the C language, with most C
operators supported on numeric operands. In addition, some
are overloaded
to operate on strings.
When an expression is used as a statement, its value is discarded after
evaluation. Therefore, only expressions with side effects
(assignments
and function calls) are useful as statements.
Single valued (non-array) variables are supported, of both
numeric and
string values. Some variables are predefined. They are
listed below.
The operators in order of increasing precedence:
<expr1> = <expr2>
Assignment. The variable of name <expr1>, which
must be
string valued, is assigned the result of
<expr2>. Returns
the value of <expr2>.
<expr1> ? <expr2> : <expr3>
Returns the value of <expr2> if <expr1> evaluates true (nonzero
numeric value); returns the value of
<expr3> otherwise.
Only one of <expr2> and <expr3> is evaluated.
<Expr1> must
be numeric.
<expr1> || <expr2>
Logical or. Numeric values only. Short circuit
evaluation
is supported (i.e., if <expr1> evaluates true,
then <expr2>
is not evaluated).
<expr1> && <expr2>
Logical and with short circuit evaluation. Numeric values
only.
<expr1> | <expr2>
Bitwise or. Numeric values only.
<expr1> ^ <expr2>
Bitwise exclusive or. Numeric values only.
<expr1> & <expr2>
Bitwise and. Numeric values only.
<expr1> == <expr2>, <expr1> != <expr2>
Comparison (equal and not equal, respectively).
The boolean
result (either 1 or 0) of the comparison is returned. The
operands can be numeric or string valued. One
string operand
forces the other to be converted to a string if
necessary.
<expr1> < <expr2>, <expr1> > <expr2>,
<expr1> <= <expr2>, <expr1> >= <expr2>
Less than, greater than, less than or equal to,
greater than
or equal to. Both numeric and string values,
with automatic
conversion as above.
<expr1> << <expr2>, <expr1> >> <expr2>
If both operands are numbers, <expr1> is bit
shifted left (or
right) by <expr2> bits. If <expr1> is a string,
then its
first (or last) <expr2> characters are returned
(if <expr2>
is also a string, then its length is used in
place of its
value).
<expr1> + <expr2>, <expr1> - <expr2>
Addition and subtraction on numbers. For `+',
if one argument
is a string, then the other is converted to
a string,
and the result is the concatenation of the two
strings.
<expr1> * <expr2>, <expr1> / <expr2>, <expr1> % <expr2>
Multiplication, division, modulo. Numbers only.
-<expr>, ~<expr>, !<expr>, $<expr>, $?<expr>
The first three are unary minus, bitwise complement and logical
complement on numbers only. The operator
`$' takes
<expr> and returns the value of the variable of
that name.
If <expr> is numeric with value n and it appears
within an
alias macro (see below), then it refers to the
nth argument
of the alias invocation. `$?' tests for the existence of the
variable <expr>, and returns 1 if it exists or 0
otherwise.
<expr>(<arglist>)
Function call. <Expr> must be a string that is
the unique
prefix of the name of a built-in window function
or the full
name of a user defined alias macro. In the case
of a builtin
function, <arglist> can be in one of two
forms:
<expr1>, <expr2>, ...
argname1 = <expr1>, argname2 = <expr2>,
...
The two forms can in fact be intermixed, but the
result is
unpredictable. Most arguments can be omitted;
default values
will be supplied for them. The argnames can be
unique prefixes
of the argument names. The commas separating arguments
are used only to disambiguate, and can usually
be omitted.
Only the first argument form is valid for user
defined aliases.
Aliases are defined using the alias builtin function
(see below). Arguments are accessed via a variant of the
variable mechanism (see the `$' operator above).
Most functions return value, but some are used
for side effect
only and so must be used as statements.
When a function
or an alias is used as a statement, the parentheses surrounding
the argument list may be omitted. Aliases
return no value.
Built-in functions [Toc] [Back]
The arguments are listed by name in their natural order.
Optional arguments
are in square brackets `[]'. Arguments that have no
names are in
angle brackets `<>'. An argument meant to be a boolean flag
(often named
flag) can be one of on, off, yes, no, true, or false, with
obvious meanings,
or it can be a numeric expression, in which case a
non-zero value
is true.
alias([<string>], [<string-list>])
If no argument is given, all currently defined
alias macros
are listed. Otherwise, <string> is defined as
an alias, with
expansion <string-list>. The previous definition of
<string>, if any, is returned. Default for
<string-list> is
no change.
close(<window-list>)
Close the windows specified in <window-list>.
If <window-
list> is the word all, than all windows are
closed. No value
is returned.
cursormodes([modes])
Set the window cursor to modes. Modes is the
bitwise or of
the mode bits defined as the variables m_ul (underline),
m_rev (reverse video), m_blk (blinking), and
m_grp (graphics,
terminal dependent). Return value is the previous modes.
Default is no change. For example, cursor($m_rev$m_blk) sets
the window cursors to blinking reverse video.
default_nline([nline])
Set the default buffer size to nline. Initially, it is 48
lines. Returns the old default buffer size.
Default is no
change. Using a very large buffer can slow the
program down
considerably.
default_shell([<string-list>])
Set the default window shell program to
<string-list>. Returns
the first string in the old shell setting.
Default is
no change. Initially, the default shell is taken from the
environment variable SHELL.
default_smooth([flag])
Set the default value of the smooth argument to
the command
window (see below). The argument is a boolean
flag (one of
on, off, yes, no, true, false, or a number, as
described
above). Default is no change. The old value
(as a number)
is returned. The initial value is 1 (true).
echo([window], [<string-list>])
Write the list of strings, <string-list>, to
window, separated
by spaces and terminated with a new line.
The strings are
only displayed in the window, the processes in
the window are
not involved (see write below). No value is returned. Default
is the current window.
escape([escapec])
Set the escape character to escape-char. Returns the old escape
character as a one-character string. Default is no
change. Escapec can be a string of a single
character, or in
the form -^X, meaning control-X.
foreground([window], [flag])
Move window in or out of foreground. Flag is a
boolean value.
The old foreground flag is returned. Default for window
is the current window, default for flag is no
change.
label([window], [label])
Set the label of window to label. Returns the
old label as a
string. Default for window is the current window, default
for label is no change. To turn off a label,
set it to an
empty string ("").
list() No arguments. List the identifiers and labels
of all windows.
No value is returned.
select([window])
Make window the current window. The previous
current window
is returned. Default is no change.
source(filename)
Read and execute the long commands in filename.
Returns -1
if the file cannot be read, 0 otherwise.
terse([flag])
Set terse mode to flag. In terse mode, the command window
stays hidden even in command mode, and errors
are reported by
sounding the terminal's bell. Flag can take on
the same values
as in foreground above. Returns the old
terse flag. Default
is no change.
unalias(alias)
Undefine alias. Returns -1 if alias does not
exist, 0 otherwise.
unset(variable)
Undefine variable. Returns -1 if variable does
not exist, 0
otherwise.
variables()
No arguments. List all variables. No value is
returned.
window([row], [column], [nrow], [ncol], [nline], [label],
[pty], [frame],
[mapnl], [keepopen], [smooth], [shell]).
Open a window with upper left corner at row,
column and size
nrow, ncol. If nline is specified, then that
many lines are
allocated for the text buffer. Otherwise, the
default buffer
size is used. Default values for row, column,
nrow, and ncol
are, respectively, the upper, leftmost, lower,
or rightmost
extremes of the screen. Label is the label
string. Frame,
pty, and mapnl are flag values interpreted in
the same way as
the argument to foreground (see above); they
mean, respectively,
put a frame around this window (default
true), allocate
pseudo-terminal for this window rather than
socketpair
(default true), and map new line characters in
this window to
carriage return and line feed (default true if
socketpair is
used, false otherwise). Normally, a window is
automatically
closed when its process exits. Setting keepopen
to true (default
false) prevents this action. When smooth
is true, the
screen is updated more frequently (for this window) to produce
a more terminal-like behavior. The default
value of
smooth is set by the default_smooth command (see
above).
Shell is a list of strings that will be used as
the shell
program to place in the window (default is the
program specified
by default_shell, see above). The created
window's
identifier is returned as a number.
write([window], [<string-list>])
Send the list of strings, <string-list>, to
window, separated
by spaces but not terminated with a new line.
The strings
are actually given to the window as input. No
value is returned.
Default is the current window.
Predefined Variables [Toc] [Back]
These variables are for information only. Redefining them
does not affect
the internal operation of window.
baud The baud rate as a number between 50 and 38400.
modes The display modes (reverse video, underline, blinking, graphics)
supported by the physical terminal. The value of
modes is the
bitwise or of some of the one bit values, m_blk,
m_grp, m_rev, and
m_ul (see below). These values are useful in setting
the window
cursors' modes (see cursormodes above).
m_blk The blinking mode bit.
m_grp The graphics mode bit (not very useful).
m_rev The reverse video mode bit.
m_ul The underline mode bit.
ncol The number of columns on the physical screen.
nrow The number of rows on the physical screen.
term The terminal type. The standard name, found in the
second name
field of the terminal's TERMCAP entry, is used.
window utilizes these environment variables: HOME, SHELL,
TERM, TERMCAP,
WINDOW_ID.
~/.windowrc startup command file
/dev/[pt]ty[pq]? pseudo-terminal devices
The window command appeared in 4.3BSD.
OpenBSD 3.6 December 30, 1993
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