Content-type: text/html Man page of window

window

Section: User Commands (1)
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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 .windowrc 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 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.

When window starts up, the commands (see Long Commands) contained in the .windowrc 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, output, and diagnostic file descriptors are bound to one end of either a pseudoterminal (pty or a UNIX domain socket, socketpair. If a pseudoterminal 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 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.

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 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. 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 current 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, \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 ; (semicolon) character. 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 (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>

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> > <expression2>, <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 prevent 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 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. Writes the list of strings, <string_list>, to 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 write, under 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. escape_character can be a string of a single character, 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 window 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 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 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.


 

Index

NAME
SYNOPSIS
OPTIONS
DESCRIPTION
Process Environment
Operation
Short Commands
Long Commands
Conditional Statements
Expressions
Built-In Functions
Predefined Variables
FILES
SEE ALSO

This document was created by man2html, using the manual pages.
Time: 02:43:01 GMT, October 02, 2010