window - Implements a window environment
window [-dft] [-c command] [-e] [escape_character]
The window command implements a window environment on
ASCII terminals.
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).
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 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 [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 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 [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 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 [Toc] [Back]
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 [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.
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 [Toc] [Back]
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 [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 (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 userdefined
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 [Toc] [Back]
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 upperleft
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 [Toc] [Back]
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.
Start-up file. Pseudoterminal devices.
Commands: stty(1)
The environ variable.
window(1)
[ Back ] |
