NetBSD/usr.bin/window/window.1

.\"	$NetBSD: window.1,v 1.21 2011/03/10 13:23:41 jmmv Exp $
.\"
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.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Edward Wang at The University of California, Berkeley.
.\"
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.\" modification, are permitted provided that the following conditions
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.\"    may be used to endorse or promote products derived from this software
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.\"	@(#)window.1	8.2 (Berkeley) 12/30/93
.\"
.Dd March 10, 2011
.Dt WINDOW 1
.Os
.Sh NAME
.Nm window
.Nd window environment
.Sh SYNOPSIS
.Nm
.Op Fl t
.Op Fl f
.Op Fl d
.Op Fl e Ar escape-char
.Op Fl c Ar command
.Sh DESCRIPTION
.Nm
implements a window environment on
.Tn ASCII
terminals.
.Pp
Please note that
.Nm
is scheduled for removal on
.Nx 7.0 .
This is the last
.Nx
release that provides
.Nm .
Use
.Xr tmux 1
instead or install the
.Sq misc/window
package from
.Xr pkgsrc 7 .
.Pp
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.
.Pp
When
.Nm
starts up, the commands (see long commands below)
contained in the file
.Pa .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.
.Pp
The command line options are
.Bl -tag -width Fl
.It Fl t
Turn on terse mode (see
.Ic terse
command below).
.It Fl f
Fast.
Don't perform any startup action.
.It Fl d
Ignore
.Pa .windowrc
and create the two default
windows instead.
.It Fl e Ar escape-char
Set the escape character to
.Ar escape-char  .
.Ar Escape-char
can be a single character, or in the form
.Ic ^X
where
.Ar X
is any character, meaning
.No control\- Ns Ar X  .
.It Fl c Ar command
Execute the string
.Ar command
as a long command (see below)
before doing anything else.
.El
.Pp
Windows can overlap and are framed as necessary.
Each window
is named by one of the digits
.Dq 1
to
.Dq 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
.Ar 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.
.Pp
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.
.Ss 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 pseudo-terminal (see
.Xr pty 4 )
or a
.Ux
domain socket (see
.Xr socketpair 2 ) .
If a pseudo-terminal is used, then its special
characters and modes (see
.Xr stty 1 )
are copied from the physical
terminal.
A
.Xr termcap 5
entry tailored to this window is created
and passed as environment (see
.Xr environ 7 )
variable
.Ev 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
.Xr vi 1
uses
this information to redraw its display.
.Ss Operation
During normal execution,
.Nm
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.
.Pp
Typing
.Nm Ns 's
escape character (normally
.Ic ^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
.Nm
interprets input from the keyboard as commands to manipulate windows.
.Pp
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
.Dq Ic \&:
command below), or read from a file (see
.Ic source
below).
.Ss Short Commands
Below,
.Ar \&#
represents one of the digits
.Dq 1
to
.Dq 9
corresponding to the windows 1 to 9.
.Ic ^X
means
.No control\- Ns Ar X  ,
where
.Ar X
is any character.
In particular,
.Ic ^^
is
.Li control\-^ .
.Ar Escape
is the escape key, or
.Ic ^\&[ .
.Bl -tag -width Ds
.It Ar #
Select window
.Ar #
as the current window
and return to conversation mode.
.It Ic \&% Ns Ar #
Select window
.Ar #
but stay in command mode.
.It Ic ^^
Select the previous window and return to conversation mode.
This is useful for toggling between two windows.
.It Ic escape
Return to conversation mode.
.It Ic ^P
Return to conversation mode and write
.Ic ^P
to the current window.
Thus, typing two
.Ic ^P Ns 's
in conversation mode sends one to the current window.
If the
.Nm
escape is changed to some other character, that
character takes the place of
.Ic ^P
here.
.It Ic \&?
List a short summary of commands.
.It Ic ^L
Refresh the screen.
.It Ic q
Exit
.Nm .
Confirmation is requested.
.It Ic ^Z
Suspend
.Nm .
.It Ic 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
.Dq h ,
.Dq j ,
.Dq k ,
and
.Dq l
move the cursor left, down, up, and right, respectively.
The keys
.Dq H ,
.Dq J ,
.Dq K ,
and
.Dq 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.
.Pp
This window becomes the current window,
and is given the first available ID.
The default buffer size is used (see
.Ar default_nline
command below).
.Pp
Only fully visible windows can be created this way.
.It Ic c Ns Ar #
Close window
.Ar # .
The process in the window is sent
the hangup signal (see
.Xr kill 1 ) .
.Xr csh 1
should
handle this signal correctly and cause no problems.
.It Ic m Ns Ar #
Move window
.Ar #
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
.Ic w
command are used to position the box.
The window can be moved partially off-screen.
.It Ic M Ns Ar #
Move window
.Ar #
to its previous position.
.It Ic s Ns Ar #
Change the size of window
.Ar # .
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
.Ic w
and
.Ic m
are used to enter the position.
.It Ic S Ns Ar #
Change window
.Ar #
to its previous size.
.It Ic ^Y
Scroll the current window up by one line.
.It Ic ^E
Scroll the current window down by one line.
.It Ic ^U
Scroll the current window up by half the window size.
.It Ic ^D
Scroll the current window down by half the window size.
.It Ic ^B
Scroll the current window up by the full window size.
.It Ic ^F
Scroll the current window down by the full window size.
.It Ic h
Move the cursor of the current window left by one column.
.It Ic j
Move the cursor of the current window down by one line.
.It Ic k
Move the cursor of the current window up by one line.
.It Ic l
Move the cursor of the current window right by one column.
.It Ic 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.
.It Ic p
Put.
The content of the yank buffer is written to the current window as input.
.It Ic ^S
Stop output in the current window.
.It Ic ^Q
Start output in the current window.
.It Ic \&:
Enter a line to be executed as long commands.
Normal line
editing characters (erase character, erase word, erase line)
are supported.
.El
.Ss 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.
.Pp
There are two data types: string and number.
A string is a sequence
of letters or digits beginning with a letter.
.Dq _
and
.Dq \&\.
are considered letters.
Alternatively, non-alphanumeric characters can
be included in strings by quoting them in double
.Pq Dq \&"
quotes or escaping them with backslash
.Pq Dq \e .
In addition, the
.Dq \e
sequences of C are supported,
both inside and outside quotes (e.g.,
.Dq \en
is a new line,
.Dq \er
a carriage return).
For example, these are legal strings:
abcde01234, "\*[Am]#$^*\*[Am]#", ab"$#"cd, ab\e$\e#cd, "/usr/ucb/window".
.Pp
A number is an integer value in one of three forms:
a decimal number, an octal number preceded by
.Dq 0 ,
or a hexadecimal number preceded by
.Dq 0x
or
.Dq 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.
.Pp
The character
.Dq #
begins a comment which terminates at the
end of the line.
.Pp
A statement is either a conditional or an expression.
Expression statements are terminated with a new line or
.Dq \&; .
To continue
an expression on the next line, terminate the first line with
.Dq \e .
.Ss Conditional Statement
.Nm
has a single control structure:
the fully bracketed if statement in the form
.Pp
.Bd -literal -offset indent -compact
if \*[Lt]expr\*[Gt] then
\t\*[Lt]statement\*[Gt]
\t...
elsif \*[Lt]expr\*[Gt] then
\t\*[Lt]statement\*[Gt]
\t...
else
\t\*[Lt]statement\*[Gt]
\t...
endif
.Ed
.Pp
The
.Ic else
and
.Ic elsif
parts are optional, and the latter can
be repeated any number of times.
\*[Lt]Expr\*[Gt]
must be numeric.
.Ss Expressions
Expressions in
.Nm
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.
.Pp
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.
.Pp
Single valued (no arrays) variables are supported, of both
numeric and string values.
Some variables are predefined.
They are listed below.
.Pp
The operators in order of increasing precedence:
.Bl -tag -width Fl
.It Ao Va expr1 Ac Ic = Ao Va expr2 Ac
Assignment.
The variable of name
.Aq Va expr1 ,
which must be string valued,
is assigned the result of
.Aq Va expr2 .
Returns the value of
.Aq Va expr2 .
.It Ao Va expr1 Ac Ic \&? Ao Va expr2 Ac : Ao Va expr3 Ac
Returns the value of
.Aq Va expr2
if
.Aq Va expr1
evaluates true
(non-zero numeric value); returns the value of
.Aq Va expr3
otherwise.
Only one of
.Aq Va expr2
and
.Aq Va expr3
is evaluated.
.Aq Va Expr1
must
be numeric.
.It Ao Va expr1 Ac Ic \&|\&| Ao Va expr2 Ac
Logical or.
Numeric values only.
Short circuit evaluation is supported
(i.e., if
.Aq Va expr1
evaluates true, then
.Aq Va expr2
is not evaluated).
.It Ao Va expr1 Ac Ic \&\*[Am]\&\*[Am] Ao Va expr2 Ac
Logical and with short circuit evaluation.
Numeric values only.
.It Ao Va expr1 Ac Ic \&| Ao Va expr2 Ac
Bitwise or.
Numeric values only.
.It Ao Va expr1 Ac Ic ^ Ao Va expr2 Ac
Bitwise exclusive or.
Numeric values only.
.It Ao Va expr1 Ac Ic \&\*[Am] Ao Va expr2 Ac
Bitwise and.
Numeric values only.
.It Ao Va expr1 Ac Ic == Ao Va expr2 Ac , Ao Va expr1 Ac Ic != Ao expr2 Ac
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 in necessary.
.It Ao Va expr1 Ac Ic \*[Lt] Ao Va expr2 Ac , \
Ao Va expr1 Ac Ic \*[Gt] Ao Va expr2 Ac , \
Ao Va expr1 Ac Ic \*[Le] Ao Va expr2 Ac ,
Less than, greater than, less than or equal to,
greater than or equal to.
Both numeric and string values, with
automatic conversion as above.
.It Ao Va expr1 Ac Ic \*[Lt]\*[Lt] Ao Va expr2 Ac , \
Ao Va expr1 Ac Ic \*[Gt]\*[Gt] Ao Va expr2 Ac
If both operands are numbers,
.Aq Va expr1
is bit
shifted left (or right) by
.Aq Va expr2
bits.
If
.Aq Va expr1
is
a string, then its first (or last)
.Aq Va expr2
characters are
returns (if
.Aq Va expr2
is also a string, then its length is used
in place of its value).
.It Ao Va expr1 Ac Ic + Ao Va expr2 Ac , Ao Va expr1 Ac Ic - Ao Va expr2 Ac
Addition and subtraction on numbers.
For
.Dq + ,
if one
argument is a string, then the other is converted to a string,
and the result is the concatenation of the two strings.
.It Ao Va expr1 Ac Ic \&* Ao Va expr2 Ac , \
Ao Va expr1 Ac Ic \&/ Ao Va expr2 Ac , Ao Va expr1 Ac Ic \&% Ao Va expr2 Ac
Multiplication, division, modulo.
Numbers only.
.It Ic \- Ns Ao Va expr Ac , Ic ~ Ns Ao Va expr Ac , \
Ic \&! Ns Ao Va expr Ac , Ic \&$ Ns Ao Va expr Ac , Ic \&$? Ns Ao Va expr Ac
The first three are unary minus, bitwise complement and logical complement
on numbers only.
The operator,
.Dq $ ,
takes
.Aq Va expr
and returns
the value of the variable of that name.
If
.Aq Va expr
is numeric
with value
.Ar n
and it appears within an alias macro (see below),
then it refers to the nth argument of the alias invocation.
.Dq $?
tests for the existence of the variable
.Aq Va expr ,
and returns 1
if it exists or 0 otherwise.
.It Ao Va expr Ac Ns Pq Aq Ar arglist
Function call.
.Aq Va Expr
must be a string that is the unique
prefix of the name of a builtin
.Nm
function
or the full name of a user defined alias macro.
In the case of a builtin function,
.Aq Ar arglist
can be in one of two forms:
.Bd -literal -offset indent
\*[Lt]expr1\*[Gt], \*[Lt]expr2\*[Gt], ...
argname1 = \*[Lt]expr1\*[Gt], argname2 = \*[Lt]expr2\*[Gt], ...
.Ed
.Pp
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
.Ar argnames
can be unique prefixes
of the argument names.
The commas separating
arguments are used only to disambiguate, and can usually be omitted.
.Pp
Only the first argument form is valid for user defined aliases.
Aliases are defined using the
.Ic alias
builtin function (see below).
Arguments
are accessed via a variant of the variable mechanism (see
.Dq $
operator above).
.Pp
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.
.El
.Ss  Builtin Functions
The arguments are listed by name in their natural order.
Optional arguments are in square brackets
.Sq Op ""
Arguments
that have no names are in angle brackets
.Sq \*[Lt]\*[Gt] .
An argument meant to be a boolean flag (often named
.Ar flag )
can be one of
.Ar on ,
.Ar off ,
.Ar yes ,
.Ar no ,
.Ar true ,
or
.Ar false ,
with
obvious meanings, or it can be a numeric expression,
in which case a non-zero value is true.
.Bl -tag -width Fl
.It Ic alias Ns Po Bo Ao Ar string Ac Bc , Bo Ao Ar string\-list Ac Bc Pc
If no argument is given, all currently defined alias macros are
listed.
Otherwise,
.Aq Ar string
is defined as an alias,
with expansion
.Aq Ar string\-list \*[Gt] .
The previous definition of
.Aq Ar string ,
if any, is returned.
Default for
.Aq Ar string\-list
is no change.
.It Ic close Ns Pq Aq Ar window\-list
Close the windows specified in
.Aq Ar window\-list .
If
.Aq Ar window\-list
is the word
.Ar all  ,
than all windows are closed.
No value is returned.
.It Ic cursormodes Ns Pq Bq Ar modes
Set the window cursor to
.Ar modes  .
.Ar Modes
is the bitwise
or of the mode bits defined as the variables
.Ar m_ul
(underline),
.Ar m_rev
(reverse video),
.Ar m_blk
(blinking),
and
.Ar m_grp
(graphics, terminal dependent).
Return value is the previous modes.
Default is no change.
For example,
.Li cursor($m_rev$m_blk)
sets the window cursors to blinking
reverse video.
.It Ic default_nline Ns Pq Bq Ar nline
Set the default buffer size to
.Ar 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.
.It Ic default_shell Ns Pq Bq Aq Ar string\-list
Set the default window shell program to
.Aq Ar 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
.Ev SHELL  .
.It Ic default_smooth Ns Pq Bq Ar flag
Set the default value of the
.Ar smooth
argument
to the command
.Nm
(see below).
The argument is a boolean flag (one of
.Ar on  ,
.Ar off  ,
.Ar yes  ,
.Ar no  ,
.Ar true  ,
.Ar 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).
.It Ic echo Ns ( Oo Ar window Oc , Bq Aq Ar string\-list )
Write the list of strings,
.Aq Ar string-list ,
to
.Nm ,
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
.Ic write
below).
No value is returned.
Default is the current window.
.It Ic escape Ns Pq Bq Ar escapec
Set the escape character to
.Ar escape-char  .
Returns the old
escape character as a one-character string.
Default is no change.
.Ar Escapec
can be a string of a single character, or
in the form
.Fl ^X ,
meaning
.No control\- Ns Ar X .
.It Ic foreground Ns ( Bo Ar window Bc , Bq Ar flag )
Move
.Nm
in or out of foreground.
.Ar Flag
is a boolean value.
The old foreground flag is returned.
Default for
.Nm
is the current window,
default for
.Ar flag
is no change.
.It Ic label Ns ( Bo Ar window Bc , Bq Ar label )
Set the label of
.Nm
to
.Ar label  .
Returns the old
label as a string.
Default for
.Nm
is the current
window, default for
.Ar label
is no change.
To turn off a label, set it to an empty string ("").
.It Ic list Ns Pq ""
No arguments.
List the identifiers and labels of all windows.
No value is returned.
.It Ic select Ns Pq Bq Ar window
Make
.Nm
the current window.
The previous current window is returned.
Default is no change.
.It Ic source Ns Pq Ar filename
Read and execute the long commands in
.Ar filename  .
Returns \-1 if the file cannot be read, 0 otherwise.
.It Ic terse Ns Pq Bq flag
Set terse mode to
.Ar flag  .
In terse mode, the command window
stays hidden even in command mode, and errors are reported by
sounding the terminal's bell.
.Ar Flag
can take on the same
values as in
.Ar foreground
above.
Returns the old terse flag.
Default is no change.
.It Ic unalias Ns Pq Ar alias
Undefine
.Ar alias  .
Returns -1 if
.Ar alias
does not exist,
0 otherwise.
.It Ic unset Ns Pq Ar variable
Undefine
.Ar variable  .
Returns -1 if
.Ar variable
does not exist,
0 otherwise.
.It Ic variables Ns Pq ""
No arguments.
List all variables.
No value is returned.
.It Ic window Ns ( Bo Ar row Bc , Bo Ar column Bc , Bo Ar nrow Bc , \
Bo Ar ncol Bc , Bo Ar nline Bc , Bo Ar label Bc , Bo Ar pty Bc , \
Bo Ar frame Bc , Bo Ar mapnl Bc , Bo Ar keepopen Bc , Bo Ar smooth Bc , \
Bo Ar shell Bc ) .
Open a window with upper left corner at
.Ar row  ,
.Ar column
and size
.Ar nrow  ,
.Ar ncol  .
If
.Ar nline
is specified,
then that many lines are allocated for the text buffer.
Otherwise, the default buffer size is used.
Default values for
.Ar row  ,
.Ar column  ,
.Ar nrow  ,
and
.Ar ncol
are, respectively,
the upper, left-most, lower, or right-most extremes of the
screen.
.Ar Label
is the label string.
.Ar Frame  ,
.Ar pty  ,
and
.Ar mapnl
are flag values
interpreted in the same way as the argument to
.Ar 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
.Ar keepopen
to true (default false) prevents this action.
When
.Ar smooth
is true, the screen is updated more frequently
(for this window) to produce a more terminal-like behavior.
The default value of
.Ar smooth
is set by the
.Ar default_smooth
command (see above).
.Ar 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
.Ar default_shell  ,
see above).
The created window's identifier is returned as a number.
.It Ic write Ns ( Bo Ar window Bc , Bq Aq Ar string\-list )
Send the list of strings,
.Aq Ar string-list ,
to
.Nm ,
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.
.El
.Ss Predefined Variables
These variables are for information only.
Redefining them does not affect the internal operation of
.Nm .
.Bl -tag -width modes
.It Ar baud
The baud rate as a number between 50 and 38400.
.It Ar modes
The display modes (reverse video, underline, blinking, graphics)
supported by the physical terminal.
The value of
.Ar modes
is the bitwise or of some of the one bit values,
.Ar m_blk ,
.Ar m_grp ,
.Ar m_rev ,
and
.Ar m_ul
(see below).
These values are useful
in setting the window cursors' modes (see
.Ar cursormodes
above).
.It Ar m_blk
The blinking mode bit.
.It Ar m_grp
The graphics mode bit (not very useful).
.It Ar m_rev
The reverse video mode bit.
.It Ar m_ul
The underline mode bit.
.It Ar ncol
The number of columns on the physical screen.
.It Ar nrow
The number of rows on the physical screen.
.It Ar term
The terminal type.
The standard name, found in the second name field of the terminal's
.Ev TERMCAP
entry, is used.
.El
.Sh ENVIRONMENT
.Nm
uses these environment variables:
.Ev HOME ,
.Ev SHELL ,
.Ev TERM ,
.Ev TERMCAP ,
.Ev WINDOW_ID .
.Sh FILES
.Bl -tag -width /dev/[pt]ty[pq]? -compact
.It Pa ~/.windowrc
startup command file.
.It Pa /dev/[pt]ty[pq]?
pseudo-terminal devices.
.El
.Sh EXAMPLES
The following example
.Pa ~/.windowrc
will open two windows.
The upper one will take one third of the screen
and run tcpdump, the lower one will take
the remaining two thirds of the screen and run
the default shell:
.Bd -literal
window r=1, nr=$nrow/3-1, l=tcpdump\e pcn0, sh=tcpdump \e-ni pcn0
window r=$nrow/3, nr=2*$nrow/3+1
.Ed
.Sh DIAGNOSTICS
Should be self explanatory.
.Sh SEE ALSO
.Xr tmux 1
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.3 .