window - Implements a window environment
window [-dft] [-c command] [-e][escape_character]
command implements a window environment
on ASCII terminals.
Executes the string
a long command (see
Long Commands) before doing
and creates the two
default windows instead.
Sets the Escape character to
can be a
single character, or in the form
Does not perform any start-up action (Fast option).
Turns on terse mode (see the
later in this reference page).
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.
Windows can overlap and are framed as necessary. Each window is named by one of the digits 1 to 9. This 1-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, nonforeground 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) can be positioned to show only a portion of its full size.
Each window has a cursor and a set of control functions. Most programmable 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, like terminals with multiple pages of memory, each window has a text buffer that can have more lines than the window itself.
starts up, the commands (see
contained in the
file in the user's home directory
are executed. If the file does not exist, two equal-sized windows spanning
the terminal screen are created by default.
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
or a UNIX domain socket,
If a pseudoterminal is used, then its special characters and modes (see the
command) are copied from the physical terminal. A
entry tailored to this window is created and passed as environment
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 pseudoterminal are set to reflect the size
of this window, and updated whenever it is changed by the user. In particular,
uses this information to redraw its display.
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 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:
are usually one or two keystrokes;
are strings that are typed in the command window (see the
Short Commands) or read from a file
(see the built-in function
The # variable represents one of the digits 1 to 9 corresponding to the windows 1 to 9. The sequence ^X means <Ctrl-x>, where x is any character. In particular, ^^ is <Ctrl-^>. escape is the <Esc> key, or ^[. Selects window # as the current window and returns to conversation mode. Selects window #, but stays in command mode. Selects the previous window and returns to conversation mode. This is useful for toggling between two windows. Returns to conversation mode. Returns to conversation mode and writes ^P to the current window. Thus, typing two ^Ps in conversation mode sends one to the current window. If the window Escape character is changed to some other character, that character takes the place of ^P here. Lists a short summary of commands. Redraws the screen. Exits window after requesting confirmation. Suspends window. Creates a new window. You are 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. Pressing <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. Pressing escape (see preceding description) at any point cancels this command.
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. The _ (underscore) and . (dot) characters are considered letters. Alternately, nonalphanumeric characters can be included in strings by escaping them with a \ (backslash). In addition, the \ sequences of C are supported, both inside and outside quotes (that is, \n is a newline, and \r a carriage-return). The following are also legal strings: abcde01234, &#$^*&#, ab$#cd, ab\$\#cd, /usr/bin/window.
A number is an integer value in one of three forms: a decimal number, an octal number preceded by 0 (zero), or a hexadecimal number preceded by 0x or 0X. The natural machine integer size is used (the signed integer type of the C compiler). As in C, a nonzero number represents a Boolean TRUE.
The # (number sign) begins a comment that terminates at the end of the line.
A statement is either a conditional or an expression. Expression statements
are terminated with a newline or with the
character. To continue an expression on the next line, terminate the first
line with a
command has a single control structure:
the fully bracketed
statement in the following form:
if <expression> then
. . .
elsif <expression> then <statement>
. . .
. . .
parts are optional,
and the latter can be repeated any number of times.
must be numeric.
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 (no arrays) variables are supported for both numeric and string values. Some variables are predefined. They are listed as follows:
The operators in order of increasing precedence are as follows: Assigns the variable <expression1>, which must be string valued, to the result of <expression2>. Returns the value of <expression2>. Returns the value of <expression2> if <expression1> evaluates TRUE (nonzero numeric value); returns the value of <expression3> otherwise. Either <expression2> and <expression3> is evaluated, but not both. <expression1> must be numeric. Performs a logical OR. Numeric values only. Short circuit evaluation is supported (that is, if <expression1> evaluates TRUE, then <expression2> is not evaluated). Performs a logical AND with short circuit evaluation. Numeric values only. Performs a bitwise OR. Numeric values only. Performs a bitwise exclusive OR. Numeric values only. Performs a bitwise AND. Numeric values only. <expression1> != <expression2>
argument1 = <expression1>, argument2 = <expression2>, ...
The arguments are listed by name in their natural order. Optional arguments
are in [ ] (brackets). Arguments that have no names are in < >
Lists all currently defined
if no argument is given. Otherwise, <string>
is defined as an alias, with expansion <string_list>.
The previous definition of <string>, if any,
is returned. Default for <string_list>
Closes the windows specified in <window_list>. If <window_list>
is the word
all, all windows are closed. No value is returned.
Sets the window cursor to
is the bitwise OR of the mode bits defined
as the variables
(graphics, terminal dependent). Return value is the previous
modes. Default is no change. For example,
sets the window cursors to blinking reverse video.
Writes the list of strings, <string_list>,
window, separated by spaces and terminated with
a newline. The strings are only displayed in the window; the processes in
the window are not involved (see the built-in function
Built-In Functions). No value is returned. Default
is the current window.
Sets the Escape character to
escape_character. Returns the old Escape character as a 1-character string.
Default is no change.
a string of a single character, or in the form
in or out of foreground.
false, with obvious meanings, or it can be a numeric
expression, in which case a nonzero value is TRUE. Returns the old foreground
flag as a number. Default for
is the current
window; default for
is no change.
Sets the label of
label. Returns the old label as a string. Default for
is the current window; default for
is no change. To turn off a label, set it to an empty string
Lists the identifiers and labels of all windows. No value
Sets the default buffer size to
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.
the current window.
The previous current window is returned. Default is no change.
Sets 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
Reads and executes the long commands in
file. Returns -1 if the file cannot be read, 0 otherwise.
Sets 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. The
can take on the same values as in
the old terse flag. Default is no change.
alias. Returns -1 if
does not exist, 0 otherwise.
variable. Returns -1
does not exist, 0 otherwise.
Lists all variables. No value is returned.
Opens a window with upper-left corner at
(column) and of size
is specified, then that many lines are allocated for the
text buffer. Otherwise, the default buffer size is used. Default values
the upper, leftmost, lower, or rightmost extremes of the screen. The
(mapnl) are flag values interpreted in the same way as
the argument to
(previously described); they
mean, respectively, put a frame around this window (default TRUE), allocate
pseudoterminal for this window rather than
TRUE), and map newline characters in this window to carriage-return and linefeed
(default TRUE if
is used, FALSE otherwise).
is a list of strings that will be used as the shell program
to place in the window (default is the program specified by
shell). The created window's identifier is returned as a number.
Sends the list of strings, <string_list>,
window, separated by spaces but not terminated
with a newline. The strings are actually given to the window as input. No
value is returned. Default is the current window.
These variables are for information only. Redefining them does not
affect the internal operation of
The baud rate as a number between 50 and 38,400.
The display modes (reverse video, underline, blinking, graphics)
supported by the physical terminal. The value of
is the bitwise OR of some of the 1-bit values,
values are useful in setting the window cursor modes (see
The blinking mode bit.
The graphics mode bit (not very useful).
The reverse video mode bit.
The underline mode bit.
The number of columns on the physical screen.
The number of rows on the physical screen.
The terminal type. The standard name, found in the second
name field of the terminal's
entry, is used.
The environ variable.