window(1) General Commands Manual window(1)
NAME
window - Implements a window environment
SYNOPSIS
window [-dft] [-c command] [-e] [escape_character]
The window command implements a window environment on ASCII terminals.
OPTIONS
Executes the string command as a long command (see Long Commands) before doing anything else. Ignores and creates the two default windows
instead. Sets the Escape character to escape_character. The escape_character can be a single character, or in the form <Ctrl-x>, where x
is any character. Does not perform any start-up action (Fast option). Turns on terse mode (see the terse command later in this reference
page).
DESCRIPTION
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 win-
dows. 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.
When window starts up, the commands (see Long Commands) 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.
Process Environment
With each newly created window, a shell program is spawned with its process environment tailored to that window. Its standard input, out-
put, and diagnostic file descriptors are bound to one end of either a pseudoterminal (pty or a UNIX domain socket, socketpair. If a pseu-
doterminal is used, then its special characters and modes (see the stty command) are copied from the physical terminal. A termcap entry
tailored to this window is created and passed as environment (environ) 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 pseudoterminal are
set to reflect the size of this window, and updated whenever it is changed by the user. In particular, the editor vi uses this information
to redraw its display.
Operation
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: short commands are usually one or two keystrokes; long commands are strings that are typed in the command
window (see the : command under Short Commands) or read from a file (see the built-in function source under Built-In Functions).
Short Commands
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 conversa-
tion 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, typ-
ing 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.
This new window becomes the current window, and is given the first available ID. The default buffer size is used (see the built-in
function nline under Built-In Functions). Only fully visible windows can be created this way. Closes window #. The process in the
window is sent the Hangup signal (see the kill command). The csh command should handle this signal correctly and cause no problems.
Moves 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 the
screen. Moves window # to its previous position. Changes the size of window #. You are prompted to enter the new lower-right cor-
ner 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.
Changes window # to its previous size. Scrolls the current window up by one line. Scrolls the current window down by one line.
Scrolls the current window up by half the window size. Scrolls the current window down by half the window size. Scrolls the cur-
rent window up by the full window size. Scrolls the current window down by the full window size. Moves the cursor of the current
window left by one column. Moves the cursor of the current window down by one line. Moves the cursor of the current window up by
one line. Moves the cursor of the current window right by one column. Stops output in the current window. Starts output in the
current window. Enters a line to be executed as long commands. Normal line editing characters (erase character, erase word, erase
line) are supported.
Long Commands
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,
is a newline, and
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 pre-
ceded 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 repre-
sents 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 ; (semicolon) char-
acter. To continue an expression on the next line, terminate the first line with a (backslash).
Conditional Statements
The window command has a single control structure: the fully bracketed if statement in the following form: if <expression> then
<statement> . . . elsif <expression> then <statement> . . . else <statement> . . . endif
The else and elsif parts are optional, and the latter can be repeated any number of times. expression must be numeric.
Expressions
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 (assign-
ments 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. <expres-
sion1> 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. Per-
forms a bitwise OR. Numeric values only. Performs a bitwise exclusive OR. Numeric values only. Performs a bitwise AND. Numeric values
only. <expression1> != <expression2>
Performs a comparison (equal and not equal, respectively). The Boolean result (either 1 or 0) is returned. The operands can be
numeric or string valued. One string operand forces the other to be converted to a string if necessary. <expression1> > <expres-
sion2>, <expression1> <= <expression2>, <expression1> >= <expression2>
Performs a less than, greater than, less than or equal to, greater than or equal to operation. Both numeric and string values, with
automatic conversion as stated previously. <expression1> >> <expression2>
Bit shifts <expression1> left (or right) by <expression2> bits if both operands are numbers. If <expression1> is a string, then its
first (or last) <expression2> characters are returned (if <expression2> is also a string, then its length is used in place of its
value). <expression1> - <expression2>
Performs 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. <expression1> / <expression2>, <expression1> % <expression2>
Performs multiplication, division, modulo. Numbers only. $<expression>, $?<expression>
Performs unary minus, bitwise complement, and logical complement on numbers only (the first three expressions, respectively). The
operator, $, takes <expression> and returns the value of the variable of that name. If <expression> is numeric with value n and it
appears within an alias macro (described later), then it refers to the nth argument of the alias invocation. $? tests for the
existence of the variable <expression>, and returns 1 if it exists or 0 otherwise. Performs a function call. <expression> 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 built-in function, <argument_list> can be in one of two forms: <expression1>, <expression2>, ...
argument1 = <expression1>, argument2 = <expression2>, ...
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. Arguments can be unique prefixes of the argument names. The commas separating arguments are used only to pre-
vent ambiguity, and can usually be omitted.
Only the first argument form is valid for user-defined aliases. Aliases are defined using the alias built-in function (described
later). Arguments are accessed through a variant of the variable mechanism (see $ operator previously described).
Most functions return a value, but some are used for side effects 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 can be omitted. Aliases return no value.
Built-In Functions
The arguments are listed by name in their natural order. Optional arguments are in [ ] (brackets). Arguments that have no names are in <
> (angle brackets). Lists all currently defined alias macros, 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> is no change. 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 cur-
sor 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. Writes the list of strings, <string_list>, to window, separated by spaces and termi-
nated with a newline. The strings are only displayed in the window; the processes in the window are not involved (see the built-in func-
tion write, under Built-In Functions). No value is returned. Default is the current window. Sets the Escape character to escape_charac-
ter. Returns the old Escape character as a 1-character string. Default is no change. escape_character can be a string of a single char-
acter, or in the form ^X, meaning <Ctrl-x>. Moves window in or out of foreground. flag can be on, off, yes, no, true, or 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 window is the current window; default for flag is no change. Sets 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 (" ").
Lists the identifiers and labels of all windows. No value is returned. Sets 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. Makes win-
dow 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
SHELL environment variable. 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 flag can take on the same values as in foreground. Returns the old terse flag. Default is no change. Undefines alias. Returns
-1 if alias does not exist, 0 otherwise. Undefines variable. Returns -1 if variable does not exist, 0 otherwise. Lists all variables.
No value is returned. Opens a window with upper-left corner at row (row), column (column) and of size nrow, ncolumn. If nline is speci-
fied, then that many lines are allocated for the text buffer. Otherwise, the default buffer size is used. Default values for row, column,
nrow, and ncolumn are, respectively, the upper, leftmost, lower, or rightmost extremes of the screen. The frame (frame), pty, and mapnl
(mapnl) are flag values interpreted in the same way as the argument to foreground (previously described); they mean, respectively, put a
frame around this window (default TRUE), allocate pseudoterminal for this window rather than socketpair (default TRUE), and map newline
characters in this window to carriage-return and linefeed (default TRUE if socketpair is used, FALSE otherwise). sh 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>, to 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.
Predefined Variables
These variables are for information only. Redefining them does not affect the internal operation of window. 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
modes is the bitwise OR of some of the 1-bit values, m_blk, m_grp, m_rev, and m_ul. These values are useful in setting the window cursor
modes (see cursormodes under Built-In Functions). 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 TERMCAP entry, is used.
FILES
Start-up file. Pseudoterminal devices.
SEE ALSO
Commands: stty(1)
The environ variable.
window(1)