\input texinfo @c -*-texinfo-*-
@c %**start of header
@setfilename screen.info
@settitle Screen User's Manual
@finalout
@setchapternewpage odd
@c %**end of header
@set version 3.5

@c For examples, use a literal escape in info.
@ifinfo
@set esc 
@end ifinfo
@iftex
@set esc <ESC>
@end iftex

@ifinfo
This file documents the the @code{Screen} virtual terminal manager.

Copyright (c) 1993 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

@ignore
Permission is granted to process this file through TeX and print the
results, provided the printed document carries copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).

@end ignore
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the entire
resulting derived work is distributed under the terms of a permission
notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that this permission notice may be stated in a translation approved
by the Foundation.
@end ifinfo

@titlepage
@title Screen
@subtitle The virtual terminal manager
@subtitle for Version @value{version}
@subtitle Aug 1993

@page
@vskip 0pt plus 1filll
Copyright @copyright{} 1993 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the entire
resulting derived work is distributed under the terms of a permission
notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that this permission notice may be stated in a translation approved
by the Foundation.
@end titlepage

@node Top, Overview, (dir), (dir)

@ifinfo
@top Screen
This file documents the @code{Screen} virtual terminal manager, version
@value{version}.
@end ifinfo

@menu
* Overview::                    Preliminary information.
* Getting Started::             An introduction to @code{screen}.
* Invoking Screen::             Command line options for @code{screen}.
* Customization::               The @file{.screenrc} file.
* Commands::                    List all of the commands.
* New Window::                  Running a program in a new window.
* Selecting::                   Selecting a window to display.
* Session Management::          Suspending or detaching a session.
* Window Settings::             titles, logging, etc.
* Virtual Terminal::            Controlling the @code{screen} VT100 emulation.
* Copy and Paste::              Exchanging text between windows and sessions.
* Subprocess Execution::	I/O filtering with @code{exec}.
* Key Binding::                 Binding commands to keys.
* Flow Control::                Trap or pass flow control characters.
* Termcap::                     Tweaking your terminal's termcap entry.
* Message Line::                The @code{screen} message line.
* Logging::                     Keeping a record of your session.
* Startup::                     Functions only useful at @code{screen} startup.
* Miscellaneous::               Various other commands.
* Environment::                 Environment variables used by @code{screen}.
* Files::                       Files used by @code{screen}.
* Credits::                     Who's who of @code{screen}.
* Bugs::                        What to do if you find a bug.
* Installation::                Getting @code{screen} running on your system.
* Concept Index::               Index of concepts.
* Command Index::               Index of all @code{screen} commands.
* Keystroke Index::             Index of default key bindings.
@end menu

@node Overview, Getting Started, Top, Top
@chapter Overview
@cindex overview

Screen is a full-screen window manager that multiplexes a physical
terminal between several processes, typically interactive shells.  Each
virtual terminal provides the functions of the DEC VT100 terminal and,
in addition, several control functions from the ANSI X3.64 (ISO 6429)
and ISO 2022 standards (e.g. insert/delete line and support for multiple
character sets).  There is a scrollback history buffer for each virtual
terminal and a copy-and-paste mechanism that allows the user to move
text regions between windows.
 
When @code{screen} is called, it creates a single window with a shell in
it (or the specified command) and then gets out of your way so that you
can use the program as you normally would.  Then, at any time, you can
create new (full-screen) windows with other programs in them (including
more shells), kill the current window, view a list of the active
windows, turn output logging on and off, copy text between windows, view
the scrollback history, switch between windows, etc.  When a program
terminates, @code{screen} (per default) kills the window that contained it.  
If this window was in the foreground, the display switches to the previously
displayed window; if none are left, @code{screen} exits.

Everything you type is sent to the program running in the current
window.  The only exception to this is the one keystroke that is used to
initiate a command to the window manager.  By default, each command
begins with a control-a (abbreviated @kbd{C-a} from now on), and is
followed by one other keystroke.  The command character (@pxref{Command
Character}) and all the key bindings (@pxref{Key Binding}) can be fully
customized to be anything you like, though they are always two
characters in length.

The standard way to create a new window is to type @kbd{C-a c}.  This
creates a new window running a shell and switches to that window
immediately, regardless of the state of the process running in the
current window.  Similarly, you can create a new window with a custom
command in it by first binding the command to a keystroke (in your
@file{.screenrc} file or at the @kbd{C-a :} command line) and then using it 
just like the @kbd{C-a c} command.  In addition, new windows can be created by 
running a command like:

@example
screen emacs prog.c
@end example

@noindent
from a shell prompt within a previously created window.  This will not
run another copy of @code{screen}, but will instead supply the command
name and its arguments to the window manager (specified in the $STY environment
variable) who will use it to create the new window.  The above example would 
start the @code{emacs} editor (editing @file{prog.c}) and switch to its window.

If @file{/etc/utmp} is writable by @code{screen}, an appropriate record
will be written to this file for each window, and removed when the
window is closed.  This is useful for working with @code{talk},
@code{script}, @code{shutdown}, @code{rsend}, @code{sccs} and other
similar programs that use the utmp file to determine who you are. As
long as @code{screen} is active on your terminal, the terminal's own
record is removed from the utmp file.  @xref{Login}.

@node Getting Started, Invoking Screen, Overview, Top
@chapter Getting Started
@cindex introduction

Before you begin to use @code{screen} you'll need to make sure you have
correctly selected your terminal type, just as you would for any other
termcap/terminfo program.  (You can do this by using @code{tset},
@code{qterm}, or just @code{set term=mytermtype}, for example.)

If you're impatient and want to get started without doing a lot more
reading, you should remember this one command: @kbd{C-a ?} (@pxref{Key
Binding}).  Typing these two characters will display a list of the
available @code{screen} commands and their bindings. Each keystroke is
discussed in the section on keystrokes (@pxref{Default Key Bindings}).
Another section (@pxref{Customization}) deals with the contents of your
@file{.screenrc}.

If possible, choose a version of your terminal's termcap that has
automatic margins turned @emph{off}.  This will ensure an accurate and
optimal update of the screen in all circumstances.  The next best thing
is an auto-margin terminal that allows the last position on the screen
to be updated without scrolling the screen (such as a vt100).  This also
allows the entire screen to be updated.  If all you've got is a
``true'' auto-margin terminal, @code{screen} will be content to use it,
but updating a character put into the last position on the screen may
not be possible until the screen scrolls or the character is moved into
a safe position in some other way.  This delay can be shortened by using
a terminal with insert-character capability.

If your terminal is of the second type (firm-margined @samp{am}), you will
want to let @code{screen} know about this, since a normal termcap
doesn't distinguish this type of automatic margins from a ``true'' @samp{am}
terminal.  You do this by specifying the @samp{xn} capability in your termcap
(@pxref{Termcap,@code{termcap} command}), or by using the @samp{-L}
command-line option.  @code{screen} needs this information to correctly
update the screen.  You don't need to worry about this if your terminal
type starts with @samp{vt}, as @code{screen} assumes @samp{xn} in that case.

If you are using a ``true'' auto-margin terminal (no @samp{xn}) at low baud
rates, you may want to turn on a more optimal output mode by including
the flag @samp{OP} in your termcap entry, or by specifying the @samp{-O}
command-line option.  The trade-off is that @code{screen} will no-longer
accurately emulate the vt100's line-end quirks (e.g. the screen will
scroll after putting @emph{one} character in the last screen position).

@xref{Special Capabilities}, for more information about telling
@code{screen} what kind of terminal you have.

@node Invoking Screen, Customization, Getting Started, Top
@chapter Invoking @code{Screen}
@cindex invoking
@cindex options
@cindex command line options

Screen has the following command-line options:

@table @samp
@item -a
Include @emph{all} capabilities (with some minor exceptions) in each
window's termcap, even if @code{screen} must redraw parts of the display
in order to implement a function.

@item -A
Adapt the sizes of all windows to the size of the display.  By default,
@code{screen} may try to restore its old window sizes when attaching to
resizeable terminals (those with @samp{WS} in their descriptions, e.g.
@code{suncmd} or some varieties of @code{xterm}).

@item -c @var{file}
Use @var{file} as the user's configuration file instead of the default
of @file{$HOME/.screenrc}.

@item -d [@var{pid.sessionname}]
@itemx -D [@var{pid.sessionname}]
Do not start @samp{screen}, but instead detach a @code{screen} session
running elsewhere (@pxref{Detach}).  @samp{-d} has the same effect as
typing @kbd{C-a d} from the controlling terminal for the session.
@samp{-D} is the equivalent to the power detach key.  If no session can
be detached, this option is ignored.  The combination @code{screen -D
-r} can be used to log out from a remote terminal and transport the
session running there to your current terminal. 
@emph{Note}: It is a good idea to check the status of your sessions
with @code{screen -list} before using this option.

@item -e @var{xy}
Set the command character to @var{x}, and the character generating a
literal command character (when typed after the command character) to
@var{y}.  The defaults are @kbd{C-a} and @kbd{a}, which can be specified
as @samp{-e^Aa}.  This option is equivalent to the @code{escape} command
(@pxref{Command Character}).

@item -f
@itemx -fn
@itemx -fa
Set flow-control to on, off, or automatic switching mode, respectively.
This option is equivalent to the @code{defflow} command (@pxref{Flow
Control}).

@item -h @var{num}
Set the history scrollback buffer to be @var{num} lines high.
Equivalent to the @code{defscrollback} command (@pxref{Copy}).

@item -i
Cause the interrupt key (usually @kbd{C-c}) to interrupt the display
immediately when flow control is on.  This option is equivalent to the
@code{interrupt} argument to the @code{defflow} command (@pxref{Flow
Control}). Its use is discouraged.

@item -l
@itemx -ln
Turn login mode on or off (for @file{/etc/utmp} updating).  This option
is equivalent to the @code{deflogin} command (@pxref{Login}).

@item -ls
@itemx -list
Do not start @code{screen}, but instead print a list of session
identification strings (usually of the form @var{pid.tty.host};
@pxref{Session Name}).  Sessions marked @samp{detached} can be resumed
with @code{screen -r}.  Those marked @samp{attached} are running and
have a controlling terminal.  Sessions marked as @samp{dead} should be
thoroughly checked and removed.  Ask your system administrator if you are
not sure why they died. Remove sessions with the @samp{-wipe} option.

@item -L
Tell @code{screen} that your auto-margin terminal allows programs to
write to the last column of the last row of the screen without
scrolling.  This can also be set in your @file{.screenrc} by specifying
@samp{xn} in a @code{termcap} command (@pxref{Termcap}).

@item -m
Tell @code{screen} to ignore the @code{$STY} environment variable.  When
this option is used, a new session will always be created, regardless of
whether @code{screen} is being called from within another @code{screen}
session or not.

@item -O
Select an output mode for your terminal which is more optimal than true
vt100 emulation (only affects auto-margin terminals without @samp{xn}).
This can also be set in your @file{.screenrc} by specifying @samp{OP} in a
@code{termcap} command (@pxref{Termcap}).

@item -r [@var{pid.sessionname}]
Resume a detached @code{screen} session.  No other options (except
@samp{-d} or @samp{-D}) may be specified, though the session name
(@pxref{Session Name}) may be needed to distinguish between multiple
detached @code{screen} sessions.

@item -R
Resume the first appropriate detached @code{screen} session.  If
successful, all other command-line options are ignored.  If no detached
session exists, start a new session using the specified options, just as
if @samp{-R} had not been specified.  This option is set by default if
screen is run as a login-shell.

@item -s @var{program}
Set the default shell to be @var{program}.  By default, @code{screen}
uses the value of the environment variable @code{$SHELL}, or
@file{/bin/sh} if it is not defined.  This option is equivalent to the
@code{shell} command (@pxref{Shell}).

@item -S @var{sessionname}
Set the name of the new session to @var{sessionname}.  This option can
be used to specify a meaningful name for the session in place of the
default @var{tty.host} suffix.  This name identifies the session for the
@code{screen -list} and @code{screen -r} commands.  This option is
equivalent to the @code{sessionname} command (@pxref{Session Name}).

@item -t @var{name}
Set the title (name) for the default shell or specified program.
This option is equivalent to the @code{shelltitle} command
(@pxref{Shell}).

@item -v
Print the version number.

@item -wipe
List available screens like @code{screen -ls}, but remove destroyed
sessions instead of marking them as @samp{dead}.

@item -x
Attach to a session which is already attached elsewhere (multi-display
mode).
@end table

@node Customization, Commands, Invoking Screen, Top
@chapter Customizing @code{Screen}
@cindex customization

You can modify the default settings for @code{screen} to fit your tastes
either through a personal @file{.screenrc} file which contains commands
to be executed at startup, or on the fly using the @code{colon} command.

@menu
* Startup Files::               The @file{.screenrc} file.
* Colon::                       Entering customization commands interactively.
@end menu

@node Startup Files, Colon,  , Customization
@section The @file{.screenrc} file
@cindex .screenrc
@cindex screenrc
When @code{screen} is invoked, it executes initialization commands from
the files @file{.screenrc} in the user's home directory and
@file{/usr/local/etc/screenrc}.  These defaults can be overridden in the 
following ways:
For the global screenrc file @code{screen} searches for the environment
variable @code{$SYSSCREENRC} (this override feature may be disabled at
compile-time).  The user specific screenrc file is
searched for in @code{$ISCREENRC}, then @code{$SCREENRC}, then
@file{@code{$HOME}/.iscreenrc} and finally defaults to
@file{@code{$HOME}/.screenrc}.  The command line option @samp{-c}
specifies which file to use (@pxref{Invoking Screen}.  Commands in these
files are used to set options, bind commands to keys, and to
automatically establish one or more windows at the beginning of
your @code{screen} session.  Commands are listed one per line, with
empty lines being ignored.  A command's arguments are separated by tabs
or spaces, and may be surrounded by single or double quotes.  A @samp{#}
turns the rest of the line into a comment, except in quotes.
Unintelligible lines are warned about and ignored.  Commands may contain
references to environment variables.  The syntax is the shell-like
@code{$VAR} or @code{$@{VAR@}}.  Note that this causes incompatibility
with previous @code{screen} versions, as now the '$'-character has to be
protected with '\' if no variable substitution is intended. A string in 
single-quotes is also protected from variable substitution.

@node Colon,  , Startup Files, Customization
@section Colon
Customization can also be done online, with this command:

@kindex :
@deffn Command colon
(@kbd{C-a :})@* 
Allows you to enter @file{.screenrc} command lines.  Useful for
on-the-fly modification of key bindings, specific window creation and
changing settings.  Note that the @code{set} keyword no longer exists,
as of version 3.3.  Change default settings with commands starting with
@samp{def}.  You might think of this as the @code{ex} command mode of
@code{screen}, with @code{copy} as its @code{vi} command mode
(@pxref{Copy and Paste}).
@end deffn

@node Commands, New Window, Customization, Top
@chapter Commands

A command in @code{screen} can either be bound to a key, invoked from a
screenrc file, or called from the @code{colon} prompt
(@pxref{Customization}).  As of version 3.3, all commands can be bound
to keys, although some may be less useful than others.

In this manual, a command definition looks like this:

@table @asis
@item -- Command: command [-n] ARG1 [ARG2] @dots{}
(@var{keybindings})@*
This command does something, but I can't remember what.
@end table

An argument in square brackets (@samp{[]}) is optional.  Many commands
take an argument of @samp{on} or @samp{off}, which is indicated as
@var{state} in the definition.

@menu
* Default Key Bindings::	@code{screen} keyboard commands.
* Command Summary::             List of all commands.
@end menu

@node Default Key Bindings, Command Summary,  , Commands
@section Default Key Bindings

As mentioned previously, each keyboard command consists of a
@kbd{C-a} followed by one other character.  For your convenience, all
commands that are bound to lower-case letters are also bound to their
control character counterparts (with the exception of @kbd{C-a a}; see
below).  Thus, both @kbd{C-a c} and @kbd{C-a C-c} can be used to create
a window.

The following table shows the default key bindings:

@table @asis
@item @kbd{C-a '}
@itemx @kbd{C-a "}
(select)@*
Prompt for a window identifier and switch.
@xref{Selecting}.

@item @kbd{C-a 0@dots{}9}
(select 0@dots{}select 9)@*
Switch to window number 0@dots{}9.  @xref{Selecting}.

@item @kbd{C-a C-a}
(other)@*
Toggle to the window displayed previously.  @xref{Selecting}.

@item @kbd{C-a a}
(meta)@*
Send the command character (C-a) to window. See @code{escape} command.
@xref{Command Character}. 

@item @kbd{C-a A}
(title)@*
Allow the user to enter a title for the current window.
@xref{Naming Windows}.

@item @kbd{C-a c}
@itemx @kbd{C-a C-c}
(screen)@*
Create a new window with a shell and switch to that window.
@xref{Screen Command}.

@item @kbd{C-a C}
(clear)@*
Clear the screen.  @xref{Clear}.

@item @kbd{C-a d}
@itemx @kbd{C-a C-d}
(detach)@*
Detach @code{screen} from this terminal.  @xref{Detach}.

@item @kbd{C-a D D}
(pow_detach)@*
Detach and logout.  @xref{Power Detach}.

@item @kbd{C-a f}
@itemx @kbd{C-a C-f}
(flow)@*
Cycle flow among @samp{on}, @samp{off} or @samp{auto}.  @xref{Flow}.

@item @kbd{C-a C-g}
(vbell)@*
Toggle visual bell mode.  @xref{Bell}.

@item @kbd{C-a h}
(hardcopy)@*
Write a hardcopy of the current window to the file ``hardcopy.@var{n}''.
@xref{Hardcopy}.

@item @kbd{C-a H}
(log)@* 
Toggle logging of the current window to the file ``screenlog.@var{n}''.
@xref{Log}.

@item @kbd{C-a i}
@itemx @kbd{C-a C-i}
(info)@*
Show info about the current window.  @xref{Info}.

@item @kbd{C-a k}
@itemx @kbd{C-a C-k}
(kill)@*
Destroy the current window.  @xref{Kill}.

@item @kbd{C-a l}
@itemx @kbd{C-a C-l}
(redisplay)@*
Fully refresh the current window.  @xref{Redisplay}.

@item @kbd{C-a L}
(login)@*
Toggle the current window's login state.  @xref{Login}.

@item @kbd{C-a m}
@itemx @kbd{C-a C-m}
(lastmsg)@*
Repeat the last message displayed in the message line.
@xref{Last Message}.

@item @kbd{C-a M}
(monitor)
Toggle monitoring of the current window.  @xref{Monitor}.

@item @kbd{C-a @key{SPC}}
@itemx @kbd{C-a n}
@itemx @kbd{C-a C-n}
(next)@*
Switch to the next window.  @xref{Selecting}.

@item @kbd{C-a N}
(number)@*
Show the number (and title) of the current window.  @xref{Number}.

@item @kbd{C-a p}
@itemx @kbd{C-a C-p}
@itemx @kbd{C-a C-h}
@itemx @kbd{C-a @key{BackSpace}}
(prev)@*
Switch to the previous window (opposite of @kbd{C-a n}).
@xref{Selecting}.

@item @kbd{C-a q}
@itemx @kbd{C-a C-q}
(xon)@*
Send a ^Q (ASCII XON) to the current window.  @xref{XON/XOFF}.

@item @kbd{C-a r}
@itemx @kbd{C-a C-r}
(wrap)@*
Toggle the current window's line-wrap setting (turn the current window's
automatic margins on or off).  @xref{Wrap}.

@item @kbd{C-a s}
@itemx @kbd{C-a C-s}
(xoff)@*
Send a ^S (ASCII XOFF) to the current window.  @xref{XON/XOFF}.

@item @kbd{C-a t}
@itemx @kbd{C-a C-t}
(time)@*
Show the load average and xref.  @xref{Time}.

@item @kbd{C-a v}
@itemx @kbd{C-a C-v}
(version)@*
Display the version and compilation date.  @xref{Version}.

@item @kbd{C-a w}
@itemx @kbd{C-a C-w}
(windows)@*
Show a list of active windows.  @xref{Windows}.

@item @kbd{C-a W}
(width)@*
Toggle between 80 and 132 columns.  @xref{Width}.

@item @kbd{C-a x}
@itemx @kbd{C-a C-x}
(lockscreen)@*
Lock your terminal.  @xref{Lock}.

@item @kbd{C-a z}
@itemx @kbd{C-a C-z}
(suspend)@*
Suspend @code{screen}.  @xref{Suspend}.

@item @kbd{C-a Z}
(reset)@*
Reset the virtual terminal to its ``power-on'' values.  
@xref{Reset}.

@item @kbd{C-a .}
(dumptermcap)@*
Write out a @file{.termcap} file.  @xref{Dump Termcap}.

@item @kbd{C-a ?}
(help)@*
Show key bindings.  @xref{Help}.

@item @kbd{C-a C-\}
(quit)@*
Kill all windows and terminate @code{screen}.  @xref{Quit}.

@item @kbd{C-a :}
(colon)@*
Enter a command line.  @xref{Colon}.

@item @kbd{C-a [}
@itemx @kbd{C-a C-[}
@itemx @kbd{C-a @key{ESC}}
(copy)@*
Enter copy/scrollback mode.  @xref{Copy}.

@item @kbd{C-a ]}
@itemx @kbd{C-a C-]}
(paste)@*
Write the contents of the paste buffer to the stdin queue of the
current window.  @xref{Paste}.

@item @kbd{C-a @{}
(history)@*
Copy and paste a previous (command) line.  @xref{History}.

@item @kbd{C-a >}
(writebuf)@*
Write the pastebuffer out to the screen-exchange file.
@xref{Screen-Exchange}.

@item @kbd{C-a <}
(readbuf)@*
Read the screen-exchange file into the pastebuffer.
@xref{Screen-Exchange}.

@item @kbd{C-a =}
(removebuf)@*
Delete the screen-exchange file.  @xref{Screen-Exchange}.

@item @kbd{C-a _}
(silence)@*
Start/stop monitoring the current window for inactivity. @xref{Silence},
@end table

@node Command Summary,  , Default Key Bindings, Commands
@section Command Summary
@cindex command summary 

@table @code
@item acladd @var{username}
Allow other user in this session.  @xref{Multiuser}.
@item aclchg @var{username permbits list}
Change a user's permissions.  @xref{Multiuser}.
@item acldel @var{username}
Disallow other user in this session.  @xref{Multiuser}.
@item activity @var{message}
Set the activity notification message.  @xref{Monitor}.
@item allpartial @var{state}
Set all windows to partial refresh.  @xref{Redisplay}.
@item at @var{[ident][@kbd{#}@var{|}@kbd{*}@var{|}@kbd{%}] command [args]}
Execute a command at other displays or windows.  @xref{At}.
@item autodetach @var{state}
Automatically detach the session on SIGHUP.  @xref{Detach}.
@item autonuke @var{state}
Enable a clear screen to discard unwritten output.  @xref{Autonuke}.
@item bell @var{message}
Set the bell notification message.  @xref{Bell}.
@item bind @var{key [command [args]]}
Bind a command to a key.  @xref{Bind}.
@item break @var{[duration]}
Send a break signal to the current window.  @xref{Break}.
@item bufferfile @var{[exchange-file]}
Select a file for screen-exchange.  @xref{Screen-Exchange}.
@item chdir @var{[directory]}
Change the current directory for future windows.  @xref{Chdir}.
@item clear
Clear the window screen.  @xref{Clear}.
@item colon
Enter a @code{screen} command.  @xref{Colon}.
@item console @var{[state]}
Grab or ungrab console output.  @xref{Console}.
@item copy
Enter copy mode.  @xref{Copy}.
@item copy_reg @var{[key]}
Store the copy buffer to a register.  @xref{Registers}.
@item crlf @var{state}
Select line break behavior for copying.  @xref{Line Termination}.
@item debug @var{state}
Suppress/allow debugging output.  @xref{Debug}.
@item defautonuke @var{state}
Select default autonuke behavior.  @xref{Autonuke}.
@item defflow @var{fstate}
Select default flow control behavior.  @xref{Flow}.
@item deflogin @var{state}
Select default utmp logging behavior.  @xref{Login}.
@item defmode @var{mode}
Select default file mode for ptys.  @xref{Mode}.
@item defmonitor @var{state}
Select default activity monitoring behavior.  @xref{Monitor}.
@item defobuflimit @var{limit}
Select default output buffer limit.  @xref{Obuflimit}.
@item defscrollback @var{num}
Set default lines of scrollback.  @xref{Scrollback}.
@item defwrap @var{state}
Set default line-wrapping behavior.  @xref{Wrap}.
@item detach
Disconnect @code{screen} from the terminal.  @xref{Detach}.
@item dumptermcap
Write the window's termcap entry to a file.  @xref{Dump Termcap}.
@item echo [-n] @var{message}
Display a message on startup.  @xref{Startup}.
@item escape @var{xy}
Set the command and @code{meta} characters.  @xref{Command Character}.
@item exec @var{[[fdpat] command [args ...]]}
Run a subprocess (filter).  @xref{Exec}.
@item flow @var{[fstate]}
Set flow control behavior.  @xref{Flow}.
@item hardcopy
Write out the contents of the current window.  @xref{Hardcopy}.
@item hardcopy_append @var{state}
Append to hardcopy files.  @xref{Hardcopy}.
@item hardcopydir @var{directory}
Place, where to dump hardcopy files.  @xref{Hardcopy}.
@item hardstatus @var{[state]}
Use the hardware status line.  @xref{Hardware Status Line}.
@item height @var{[lines]}
Set display height.  @xref{Height}.
@item help
Display current key bindings.  @xref{Help}.
@item history
Find previous command beginning @dots{}.  @xref{History}.
@item info
Display terminal settings.  @xref{Info}.
@item ins_reg @var{[key]}
Paste the contents of a register.  @xref{Registers}.
@item kill
Destroy the current window.  @xref{Kill}.
@item lastmsg
Redisplay the last message.  @xref{Last Message}.
@item license
Display licensing information.  @xref{Startup}.
@item lockscreen
Lock the controlling terminal.  @xref{Lock}.
@item log @var{[state]}
Log all output in the current window.  @xref{Log}.
@item logdir @var{directory}
Place where to collect logfiles.  @xref{Log}.
@item login @var{[state]}
Log the window in @file{/etc/utmp}.  @xref{Login}.
@item markkeys @var{string}
Rebind keys in copy mode.  @xref{Copy Mode Keys}.
@item meta
Insert the command character.  @xref{Command Character}.
@item monitor @var{[state]}
Monitor activity in window.  @xref{Monitor}.
@item msgminwait @var{sec}
Set minimum message wait.  @xref{Message Wait}.
@item msgwait @var{sec}
Set default message wait.  @xref{Message Wait}.
@item multiuser @var{state}
Go into single or multi user mode. @xref{Multiuser}.
@item nethack @var{state}
Use @code{nethack}-like error messages.  @xref{Nethack}.
@item next
Switch to the next window.  @xref{Selecting}.
@item number @var{[n]}
Change/display the current window's number.  @xref{Number}.
@item obuflimit @var{[limit]}
Select output buffer limit.  @xref{Obuflimit}.
@item other
Switch to the window you were in last.  @xref{Selecting}.
@item partial @var{state}
Set window to partial refresh.  @xref{Redisplay}.
@item password @var{[crypted_pw]}
Set reattach password.  @xref{Detach}.
@item paste
Paste contents of copy buffer.  @xref{Paste}.
@item pow_break
Close and Reopen the window's terminal.  @xref{Break}.
@item pow_detach
Detach and hang up.  @xref{Power Detach}.
@item pow_detach_msg @var{message}
Set message displayed on @code{pow_detach}.  @xref{Power Detach}.
@item prev
Switch to the previous window.  @xref{Selecting}.
@item process @var{[key]}
Treat a register as input to @code{screen}.  @xref{Registers}.
@item quit
Kill all windows and exit.  @xref{Quit}.
@item readbuf
Read the copy buffer from the screen-exchange file.  @xref{Screen-Exchange}.
@item redisplay
Redisplay the current window.  @xref{Redisplay}.
@item register @var{key string}
Store a string to a register.  @xref{Registers}.
@item removebuf
Delete the screen-exchange file.  @xref{Screen-Exchange}.
@item reset
Reset the terminal settings for the window.  @xref{Reset}.
@item screen @var{[opts] [n] [cmd [args]]}
Create a new window.  @xref{Screen Command}.
@item scrollback @var{num}
Set size of scrollback buffer.  @xref{Scrollback}.
@item select @var{[n]}
Switch to a specified window.  @xref{Selecting}.
@item sessionname @var{[name]}
Name this session.  @xref{Session Name}.
@item setenv @var{[var [string]]}
Set an environment variable for new windows.  @xref{Setenv}.
@item shell @var{command}
Set the default program for new windows.  @xref{Shell}.
@item shelltitle @var{title}
Set the default name for new windows.  @xref{Shell}.
@item silence @var{[state|seconds]}
Monitor window for inactivity.  @xref{Silence}.
@item silencewait @var{seconds}
Default timeout to trigger an inactivity notify.  @xref{Silence}.
@item sleep @var{num}
Pause during startup.  @xref{Startup}.
@item slowpaste @var{msec}
Slow down pasting.  @xref{Paste}.
@item startup_message @var{state}
Display copyright notice on startup.  @xref{Startup}.
@item suspend
Put session in background.  @xref{Suspend}.
@item term @var{term}
Set @code{$TERM} for new windows.  @xref{Term}.
@item termcap @var{term terminal-tweaks [window-tweaks]}
Tweak termcap entries for best performance.  @xref{Termcap Syntax}.
@item terminfo @var{term terminal-tweaks [window-tweaks]}
Ditto, for terminfo systems.  @xref{Termcap Syntax}.
@item time
Display time and load average.  @xref{Time}.
@item title @var{[windowtitle]}
Set the name of the current window.  @xref{Title Command}.
@item unsetenv @var{var}
Unset environment variable for new windows.  @xref{Setenv}.
@item vbell @var{[state]}
Use visual bell.  @xref{Bell}.
@item vbell_msg @var{message}
Set vbell message.  @xref{Bell}.
@item vbellwait @var{sec}
Set delay for vbell message.  @xref{Bell}.
@item version
Display @code{screen} version.  @xref{Version}.
@item wall @var{message ...}
Write a message to all displays.  @xref{Multiuser}.
@item width @var{[num]}
Set the width of the window.  @xref{Width}.
@item windows
List active windows.  @xref{Windows}.
@item wrap @var{[state]}
Control line-wrap behavior.  @xref{Wrap}.
@item writebuf
Write copy buffer to screen-exchange file.  @xref{Screen-Exchange}.
@item writelock @var{on|off|auto}
Grant exclusive write permission.  @xref{Multiuser}.
@item xoff
Send an XOFF character.  @xref{XON/XOFF}.
@item xon
Send an XON character.  @xref{XON/XOFF}.
@item zombie @var{[key]}
Keep dead windows.  @xref{Zombie}.
@end table

@node New Window, Selecting, Commands, Top
@chapter New Window

This section describes the commands for creating a new window for
running programs.  When a new window is created, the first available
number from the range 0@dots{}9 is assigned to it.  There can be no more
than 10 windows active at any one time.

@menu
* Chdir::                       Change the working directory for new windows.
* Screen Command::              Create a new window.
* Setenv::                      Set environment variables for new windows.
* Shell::                       Parameters for shell windows.
* Term::                        Set the terminal type for new windows.
@end menu

@node Chdir, Screen Command,  , New Window
@section Chdir
@deffn Command chdir [directory]
(none)@*
Change the current directory of @code{screen} to the specified directory
or, if called without an argument, to your home directory (the value of
the environment variable @code{$HOME}).  All windows that are created by means
of the @code{screen} command from within @file{.screenrc} or by means of
@kbd{C-a : screen @dots{}} or @kbd{C-a c} use this as their default
directory.  Without a @code{chdir} command, this would be the directory
from which @code{screen} was invoked.  Hardcopy and log files are always
written to the @emph{window's} default directory, @emph{not} the current
directory of the process running in the window.  You can use this
command multiple times in your @file{.screenrc} to start various windows
in different default directories, but the last @code{chdir} value will
affect all the windows you create interactively.
@end deffn

@node Screen Command, Setenv, Chdir, New Window
@section Screen Command
@kindex c
@kindex C-c
@deffn Command screen [opts] [n] [cmd [args]]
(@kbd{C-a c}, @kbd{C-a C-c})@*
Establish a new window.  The flow-control options (@samp{-f}, @samp{-fn}
and @samp{-fa}), title option (@samp{-t}), login options
(@samp{-l} and @samp{-ln}) , terminal type option (@samp{-T @var{term}})
and scrollback option (@samp{-h @var{num}}) may be specified for each
command.  If an optional number @var{n} in the range 0@dots{}9 is given,
the window number @var{n} is assigned to the newly created window (or,
if this number is already in-use, the next available number).  If a
command is specified after @code{screen}, this command (with the given
arguments) is started in the window; otherwise, a shell is created.
@end deffn

Thus, if your @file{.screenrc} contains the lines

@example
# example for .screenrc:
screen 1
screen -fn -t foobar 2 telnet foobar
@end example

@noindent
@code{screen} creates a shell window (in window #1) and a window with a
TELNET connection to the machine foobar (with no flow-control using the
title @samp{foobar} in window #2).  If you do not include any
@code{screen} commands in your @file{.screenrc} file, then @code{screen}
defaults to creating a single shell window, number zero.  When the
initialization is completed, @code{screen} switches to the last window
specified in your .screenrc file or, if none, it opens default window
#0.

@node Setenv, Shell, Screen Command, New Window
@section Setenv
@deffn Command setenv var string
(none)@*
Set the environment variable @var{var} to value @var{string}.
If only @var{var} is specified, the user will be prompted to enter a value.
If no parameters are specified, the user will be prompted for both variable
and value. The environment is inherited by all subsequently forked shells.
@end deffn

@deffn Command unsetenv var
(none)@*
Unset an environment variable.
@end deffn

@node Shell, Term, Setenv, New Window
@section Shell
@deffn Command shell command
(none)@*
Set the command to be used to create a new shell.  This overrides the
value of the environment variable @code{$SHELL}.  This is useful if
you'd like to run a tty-enhancer which is expecting to execute the
program specified in @code{$SHELL}.  If the command begins with
a @samp{-} character, the shell will be started as a login-shell.
@end deffn

@deffn Command shelltitle title
(none)@*
Set the title for all shells created during startup or by the C-a C-c
command.  @xref{Naming Windows}, for details about what titles are.
@end deffn

@node Term,  , Shell, New Window
@section Term
@deffn Command term term
(none)@*
In each window @code{screen} opens, it sets the @code{$TERM}
variable to @samp{screen} by default, unless no description for
@samp{screen} is installed in the local termcap or terminfo data base.
In that case it pretends that the terminal emulator is @samp{vt100}.
This won't do much harm, as @code{screen} is VT100/ANSI compatible.  The
use of the @code{term} command is discouraged for non-default purpose.
That is, one may want to specify special @code{$TERM} settings (e.g. vt100) for
the next @code{screen rlogin othermachine} command. Use the command
@code{screen -T vt100 rlogin othermachine} rather than setting
(@code{term vt100}) and resetting (@code{term screen}) the default
before and after the @code{screen} command.
@end deffn

@node Selecting, Session Management, New Window, Top
@chapter Selecting a Window

This section describes the commands for switching between windows in an
@code{screen} session.  The windows are numbered from 0 to 9, and are created
in that order by default (@pxref{New Window}).

@menu
* Next and Previous::           Forward or back one window.
* Other Window::                Switch back and forth between two windows.
* Select::                      Specify a particular window.
@end menu

@node Next and Previous, Other Window,  , Selecting
@section Moving Back and Forth
@kindex SPC
@kindex n
@kindex C-n
@deffn Command next
(@kbd{C-a @key{SPC}}, @kbd{C-a n}, @kbd{C-a C-n})@*
Switch to the next window.  This command can be used repeatedly to
cycle through the list of windows.  (On some terminals, C-@key{SPC}
generates a NUL character, so you must release the control key before
pressing space.)
@end deffn

@kindex p
@kindex C-p
@deffn Command prev
(@kbd{C-a p}, @kbd{C-a C-p})@*
Switch to the previous window (the opposite of @kbd{C-a n}).
@end deffn

@node Other Window, Select, Next and Previous, Selecting
@section Other Window
@kindex C-a
@deffn Command other
(@kbd{C-a C-a})@*
Switch to the last window displayed.  Note that this command
defaults to the command character typed twice, unless overridden; for
instance, if you use the option @samp{-e]x}, this command becomes
@kbd{]]}, not @kbd{]C-a} (@pxref{Command Character}).  On the other
hand, if you use the option @samp{-e``}, this command remains @kbd{`
C-a}, since @kbd{``} is bound to @code{meta}.
@end deffn

@node Select,  , Other Window, Selecting
@section Select
@kindex 0@dots{}9
@kindex '
@kindex "
@deffn Command select [n]
(@kbd{C-a @var{n}}, @kbd{C-a '}, @kbd{C-a "})@*
Switch to the window with the number @var{n}.
If no window number is specified, you get prompted for an 
identifier. This can be a window name (title) or a number.
@end deffn

@node Session Management, Window Settings, Selecting, Top
@chapter Session Management Commands

Perhaps the most useful feature of @code{screen} is the way it allows
the user to move a session between terminals, by detaching and
reattaching.  This also makes life easier for modem users who have to
deal with unexpected loss of carrier.

@menu
* Detach::                      Disconnect @code{screen} from your terminal.
* Power Detach::                Detach and log out.
* Lock::                        Lock your terminal temporarily.
* Multiuser Session::		Changing number of allowed users.
* Session Name::                Rename your session for later reattachment.
* Suspend::                     Suspend your session.
* Quit::                        Terminate your session.
@end menu

@node Detach, Power Detach,  , Session Management
@section Detach

@deffn Command autodetach state
(none)@*
Sets whether @code{screen} will automatically detach upon hangup, which
saves all your running programs until they are resumed with a
@code{screen -r} command.  When turned off, a hangup signal will
terminate @code{screen} and all the processes it contains. Autodetach is
on by default.
@end deffn

@kindex d
@kindex C-d
@deffn Command detach
(@kbd{C-a d}, @kbd{C-a C-d})@*
Detach the @code{screen} session (disconnect it from the terminal and
put it into the background).  A detached @code{screen} can be resumed by
invoking @code{screen} with the @code{-r} option. (@pxref{Invoking
Screen})
@end deffn

@deffn Command password [crypted_pw]
(none)@*
Present a crypted password in your @file{.screenrc} file and screen will
ask for it, whenever someone attempts to resume a detached session. This
is useful, if you have privileged programs running under @code{screen}
and you want to protect your session from reattach attempts by users
that managed to assume your uid. (I.e. any superuser.)  If no crypted
password is specified, screen prompts twice a password and places its
encryption in the copybuffer.  Default is `none', which disables
password checking.
@end deffn

@node Power Detach, Lock, Detach, Session Management
@section Power Detach

@kindex D
@deffn Command pow_detach
(@kbd{C-a D})@*
Mainly the same as @code{detach}, but also sends a HANGUP signal
to the parent process of @code{screen}.@*
@emph{Caution}: This will result in a
logout if @code{screen} was started from your login shell.
@end deffn

@deffn Command pow_detach_msg message
(none)@*
The @var{message} specified here is output whenever a power detach is
performed. It may be used as a replacement for a logout message or to reset 
baud rate, etc.
@end deffn

@node Lock, Multiuser Session, Power Detach, Session Management
@section Lock
@kindex x
@kindex C-x
@deffn Command lockscreen
(@kbd{C-a x}, @kbd{C-a C-x})@*
Call a screenlock program (@file{/local/bin/lck} or @file{/usr/bin/lock}
or a builtin, if no other is available). Screen does not accept any
command keys until this program terminates. Meanwhile processes in the
windows may continue, as the windows are in the detached state.
The screenlock program may be changed through the environment variable
@code{$LOCKPRG} (which must be set in the shell from which @code{screen}
is started) and is executed with the user's uid and gid.
@end deffn

@node Multiuser Session, Session Name, Lock, Session Management
@section Multiuser Session
@cindex multiuser session 

These commands allow other users to gain access to one single @code{screen}
session. When attaching to a multiuser @code{screen} the sessionname is 
specified as @code{username/sessionname} to the @code{-S} command line option.
@code{Screen} must be compiled with multiuser support to enable features 
described here.

@menu
* Multiuser::			Enable / Disable multiuser mode.
* Acladd::			Enable a specific user.
* Aclchg::                      Change a users permissions.
* Acldel::			Disable a specific user.
* Wall::                        Write a message to all users.
* Writelock::                   Grant exclusive window access.
@end menu

@node Multiuser, Acladd,  , Multiuser Session
@subsection Multiuser
@deffn Command multiuser @var{state}
(none)@*
Switch between single-user and multi-user mode. Standard screen operation is 
single-user. In multi-user mode the commands @code{acladd} and @code{acldel}
can be used to enable (and disable) other users accessing this @code{screen}.
@end deffn

@node Acladd, Aclchg, Multiuser, Multiuser Session
@subsection Acladd
@deffn Command acladd @var{username}
(none)@*
Enable a user to (fully) access this screen session. Necessary to allow other
users to attach to this @code{screen} session. Same as 
@code{aclchg @var{username} +rwx "#?"}. Multi-user mode only.
@end deffn

@node Aclchg, Acldel, Acladd, Multiuser Session
@subsection Aclchg
@deffn Command aclchg @var{username permbits list}
(none)@*
Change a users permissions. Permission bits are represented as @samp{r}, 
@samp{w} and @samp{x}. Prefixing @samp{+} grants the permission, @samp{-} 
removes it. The third parameter is a komma seperated list of commands or windows
(specified either by number or title). The special list @samp{#} refers to all 
windows, @samp{?} to all commands.
A Command can be executed when the user has the @samp{x} bit for it. the user
can type input to a window, when he has its @samp{w} bit set and no other
user obtains a writelock for this window. Other bits are currently ignored.
Multi-user mode only.
@end deffn

@node Acldel, Wall, Aclchg, Multiuser Session
@subsection Acldel
@deffn Command acldel @var{username}
(none)@*
Remove a user from screens access control list. If currently attached, all the
users displays are detached from the session. He cannot attach again.
Multi-user mode only.
@end deffn

@node Wall, Writelock, Acldel, Multiuser Session
@subsection Wall
@deffn Command wall @var{message ...}
(none)@*
Write a message to all displays. The message will appear in the terminals
status line.
@end deffn

@node Writelock,  , Wall, Multiuser Session
@subsection Writelock
@deffn Command writelock @var{on|off|auto}
(none)@*
In addition to access control lists, not all users may be able to write to
the same window at once. Per default, writelock is in @samp{auto} mode and
grants exclusive input permission to the user who is the first to switch
to the particular window. When he leaves the window, other users may obtain
the writelock (automatically). The writelock of the current window is disabled
by the command @code{writelock off}. If the user issues the command
@code{writelock on} he keeps the exclusive write permission while switching
to other windows.
@end deffn

@node Session Name, Suspend, Multiuser Session, Session Management
@section Session Name
@deffn Command sessionname [name]
(none)@*
Rename the current session. Note that for @code{screen -list} the name
shows up with the process-id prepended. If the argument @var{name} is
omitted, the name of this session is displayed.@*
@emph{Caution}: The @code{$STY}
environment variable still reflects the old name. This may result in
confusion.  The default is constructed from the tty and host names.
@end deffn

@node Suspend, Quit, Session Name, Session Management
@section Suspend
@kindex z
@kindex C-z
@deffn Command suspend
(@kbd{C-a z}, @kbd{C-a C-z})@*
Suspend @code{screen}.  The windows are in the detached state while
@code{screen} is suspended.  This feature relies on the parent shell
being able to do job control.
@end deffn

@node Quit,  , Suspend, Session Management
@section Quit
@kindex C-\
@deffn Command quit
(@kbd{C-a C-\})@*
Kill all windows and terminate @code{screen}.  Note that on vt100-style
terminals the keys @kbd{C-4} and @kbd{C-\} are identical.  So be careful
not to type @kbd{C-a C-4} when selecting window no. 4.  Use the empty
bind command (as in @code{bind "^\"}) to remove a key binding
(@pxref{Key Binding}).
@end deffn

@node Window Settings, Virtual Terminal, Session Management, Top
@chapter Window Settings

These commands control the way @code{screen} treats individual windows
in a session.  @xref{Virtual Terminal}, for comands to control the
terminal emulation itself.

@menu
* Naming Windows::               Control the name of the window
* Autonuke::			Flush unseen output
* Console::			See the host's console messages
* Kill::                        Destroy an unwanted window
* Login::                       Control @file{/etc/utmp} logging
* Mode::                        Control the file mode of the pty
* Monitor::                     Watch for activity in a window
* Obuflimit::			Allow pending output when reading more
* Windows::                     List the active windows
@end menu

@node Naming Windows, Autonuke,  , Window Settings
@section Naming Windows (Titles)
@cindex title

You can customize each window's name in the window display (viewed with
the @code{windows} command (@pxref{Windows}) by setting it with
one of the title commands.  Normally the name displayed is the actual
command name of the program created in the window.  However, it is
sometimes useful to distinguish various programs of the same name or to
change the name on-the-fly to reflect the current state of the window.

The default name for all shell windows can be set with the
@code{shelltitle} command (@pxref{Shell}).  You can specify the name you
want for a window with the @samp{-t} option to the @code{screen} command
when the window is created (@pxref{Screen Command}).  To change the name after
the window has been created you can use the title-string escape-sequence
(@kbd{@key{ESC} k @var{name} @key{ESC} \}) and the @code{title} command
(C-a A).  The former can be output from an application to control the
window's name under software control, and the latter will prompt for a
name when typed.  You can also bind predefined names to keys with the
@code{title} command to set things quickly without prompting.

@menu
* Title Command::                 The @code{title} command.
* Dynamic Titles::                Make shell windows change titles dynamically.
* Title Prompts::                 Set up your shell prompt for dynamic Titles.
* Title Screenrc::                Set up Titles in your @file{.screenrc}.
@end menu

@node Title Command, Dynamic Titles,  , Naming Windows
@subsection Title Command
@kindex A
@deffn Command title [windowtitle]
(@kbd{C-a A})@*
Set the name of the current window to @var{windowalias}. If no name is 
specified, screen prompts for one.
@end deffn

@node Dynamic Titles, Title Prompts, Title Command, Naming Windows
@subsection Dynamic Titles
@code{screen} has a shell-specific heuristic that is enabled by
setting the window's name to @var{search|name} and arranging to have a
null title escape-sequence output as a part of your prompt.  The
@var{search} portion specifies an end-of-prompt search string, while the
@var{name} portion specifies the default shell name for the window.  If
the @var{name} ends in a @samp{:} @code{screen} will add what it
believes to be the current command running in the window to the end of
the specified name (e.g. @var{name:cmd}).  Otherwise the current
command name supersedes the shell name while it is running.

Here's how it works: you must modify your shell prompt to output a null
title-escape-sequence (@key{ESC} k @key{ESC} \) as a part of your prompt.
The last part of your prompt must be the same as the string you
specified for the @var{search} portion of the title.  Once this is set
up, @code{screen} will use the title-escape-sequence to clear the previous
command name and get ready for the next command.  Then, when a newline
is received from the shell, a search is made for the end of the prompt.
If found, it will grab the first word after the matched string and use
it as the command name.  If the command name begins with @samp{!},
@samp{%}, or @samp{^}, @code{screen} will use the first word on the
following line (if found) in preference to the just-found name.  This
helps csh users get more accurate titles when using job control or
history recall commands.

@node Title Prompts, Title Screenrc, Dynamic Titles, Naming Windows
@subsection Setting up your prompt for shell titles
One thing to keep in mind when adding a null title-escape-sequence to your
prompt is that some shells (like the csh) count all the non-control
characters as part of the prompt's length.  If these invisible
characters aren't a multiple of 8 then backspacing over a tab will
result in an incorrect display.  One way to get around this is to use a
prompt like this:

@example
set prompt='@value{esc}[0000m@value{esc}k@value{esc}\% '
@end example

The escape-sequence @samp{@value{esc}[0000m} not only normalizes the
character attributes, but all the zeros round the length of the
invisible characters up to 8.

Tcsh handles escape codes in the prompt more intelligently, so you can
specify your prompt like this:

@example
set prompt="%@{\ek\e\\%@}\% "
@end example

Bash users will probably want to echo the escape sequence in the
PROMPT_COMMAND:

@example
PROMPT_COMMAND='echo -n -e "\033k\033\134"'
@end example

(I used @samp{\134} to output a @samp{\} because of a bug in v1.04).

@node Title Screenrc,  , Title Prompts, Naming Windows
@subsection Setting up shell Titles in your @file{.screenrc}
Here are some .screenrc examples:

@example
screen -t top 2 nice top
@end example

Adding this line to your .screenrc would start a niced version of the
@code{top} command in window 2 name @samp{top} rather than @samp{nice}.

@example
shelltitle '> |csh'
screen 1
@end example

This file would start a shell using the given shelltitle.  The title
specified is an auto-title that would expect the prompt and the typed
command to look something like the following:

@example
/usr/joe/src/dir> trn
@end example

(it looks after the '> ' for the command name).
The window status would show the name @samp{trn} while the command was
running, and revert to @samp{csh} upon completion.

@example
bind R screen -t '% |root:' su
@end example

Having this command in your .screenrc would bind the key sequence
@kbd{C-a R} to the @code{su} command and give it an auto-title name of
@samp{root:}.  For this auto-title to work, the screen could look
something like this:

@example
% !em
emacs file.c
@end example

Here the user typed the csh history command @code{!em} which ran the
previously entered @code{emacs} command.  The window status would show
@samp{root:emacs} during the execution of the command, and revert to
simply @samp{root:} at its completion.

@example
bind o title
bind E title ""
bind u title (unknown)
@end example

The first binding doesn't have any arguments, so it would prompt you for
a title when you type @kbd{C-a o}.  The second binding would clear an
auto-titles current setting (C-a E).  The third binding would set the
current window's title to @samp{(unknown)} (C-a u).

@node Autonuke, Console, Naming Windows, Window Settings
@section Autonuke
@deffn Command autonuke @var{state}
(none)@*
Sets whether a clear screen sequence should nuke all the output
that has not been written to the terminal. @xref{Obuflimit}.
@end deffn

@deffn Command defautonuke @var{state}
(none)@*
Same as the @code{autonuke} command except that the default setting for
new displays is changed. Initial setting is @code{off}. 
Note that you can use the special @code{AN} terminal capability if you
want to have a terminal type dependant setting.
@end deffn

@node Console, Kill, Autonuke, Window Settings
@section Console
@deffn Command console @var{[state]}
(none)@*
Grabs or ungrabs the machines console output to a window. When the argument
is ommitted the current state is displayed.
@end deffn

@node Kill, Login, Console, Window Settings
@section Kill

@kindex k
@kindex C-k
@deffn Command kill
(@kbd{C-a k}, @kbd{C-a C-k})@*
Kill the current window.@*
If there is an @code{exec} command running (@pxref{Exec}) then it is killed.
Otherwise the process (e.g. shell) running in the window receives a 
@code{HANGUP} condition, 
the window structure is removed and screen switches to the previously 
displayed window. When the last window is destroyed, @code{screen} exits.
@* 
@emph{Caution}: @code{emacs} users may find themselves killing their
@code{emacs} session when trying to delete the current line.  For this
reason, it is probably wise to use a different command character
(@pxref{Command Character}) or rebind @code{kill} to another key
sequence, such as @kbd{C-a K} (@pxref{Key Binding}).
@end deffn

@node Login, Mode, Kill, Window Settings
@section Login

@deffn Command deflogin state
(none)@*
Same as the @code{login} command except that the default setting for new
windows is changed.  This defaults to `on' unless otherwise specified at
compile time (@pxref{Installation}). Both commands are only present when
@code{screen} has been compiled with utmp support.
@end deffn

@kindex L
@deffn Command login [state]
(@kbd{C-a L})@*
Adds or removes the entry in @file{/etc/utmp} for the current window.
This controls whether or not the window is @dfn{logged in}.  In addition
to this toggle, it is convenient to have ``log in'' and ``log out''
keys.  For instance, @code{bind I login on} and @code{bind O 
login off} will map these keys to be @kbd{C-a I} and @kbd{C-a O}
(@pxref{Key Binding}).
@end deffn

@node Mode, Monitor, Login, Window Settings
@section Mode
@deffn Command defmode mode
(none)@*
The mode of each newly allocated pseudo-tty is set to @var{mode}.
@var{mode} is an octal number as used by chmod(1).  Defaults to 0622 for
windows which are logged in, 0600 for others (e.g. when @code{-ln} was 
specified for creation. @pxref{Screen Command}).
@end deffn

@node Monitor, Obuflimit, Mode, Window Settings
@section Monitoring

@deffn Command activity message
(none)@*
When any activity occurs in a background window that is being monitored,
@code{screen} displays a notification in the message line.  The
notification message can be redefined by means of the @code{activity}
command.  Each occurrence of @samp{%} in @var{message} is replaced by
the number of the window in which activity has occurred, and each
occurrence of @samp{~} is replaced by the definition for bell in your
termcap (usually an audible bell).  The default message is

@example
'Activity in window %'
@end example

Note that monitoring is off for all windows by default, but can be altered
by use of the @code{monitor} command (@kbd{C-a M}).
@end deffn

@deffn Command defmonitor state
(none)@*
Same as the @code{monitor} command except that the default setting for
new windows is changed.  Initial setting is `off'.
@end deffn

@kindex M
@deffn Command monitor [state]
(@kbd{C-a M})@*
Toggles monitoring of the current window.  When monitoring is turned on
and the affected window is switched into the background, the activity
notification message will be displayed in the status line at the first
sign of output, and the window will also be marked with an @samp{@@} in
the window-status display (@pxref{Windows}).  Monitoring defaults to
@samp{off} for all windows.
@end deffn

@node Obuflimit, Windows, Monitor, Window Settings
@section Obuflimit
@deffn Command obuflimit @var{[limit]}
(none)@*
If the output buffer contains more bytes than the specified limit, no
more data will be read from the windows. The default value is 256. If
you have a fast display (like @code{xterm}), you can set it to some 
higher value. If no argument is specified, the current setting is displayed.
@end deffn

@deffn Command defobuflimit @var{limit}
(none)@*
Same as the @code{obuflimit} command except that the default setting for new
displays is changed. Initial setting is 256 bytes. Note that you can use
the special @code{OL} terminal capability if you want to have a terminal
type dependant limit.
@end deffn

@node Windows,  , Obuflimit, Window Settings
@section Windows
@kindex w
@kindex C-w
@deffn Command windows
(@kbd{C-a w}, @kbd{C-a C-w})@*
Uses the message line to display a list of all the windows.  Each
window is listed by number with the name of the program running in the
window (or its title); the current window is marked with a @samp{*};
the previous window is marked with a @samp{-}; all the windows that are
logged in are marked with a @samp{$} (@pxref{Login}); a background
window that has received a bell is marked with a @samp{!}; a background
window that is being monitored and has had activity occur is marked with
an @samp{@@} (@pxref{Monitor}); a window which has output logging turned
on is marked with @samp{(L)}; windows occupied by other users are marked with 
@samp{&}; windows in the zombie state are marked with @samp{Z}. 
If this list is too long to fit on the terminals status line only the
portion around the current window is displayed.
@end deffn

@node Virtual Terminal, Copy and Paste, Window Settings, Top
@chapter Virtual Terminal

Each window in a @code{screen} session emulates a VT100 terminal, with
some extra functions added.  The commands described here modify the
terminal emulation.

@menu
* Control Sequences::           Details of the internal VT100 emulation.
* Bell::                        Getting your attention.
* Clear::                       Clear the window display.
* Height::			Changing the height of your terminal.
* Info::                        Terminal emulation statistics.
* Redisplay::                   When the display gets confusing.
* Wrap::                        Automatic margins.
* Reset::                       Recovering from ill-behaved applications.
* Width::                       Changing the width of your terminal.
@end menu

@node Control Sequences, Bell,  , Virtual Terminal
@section Control Sequences
@cindex control sequences
The following is a list of control sequences recognized by
@code{screen}.  @samp{(V)} and @samp{(A)} indicate VT100-specific and
ANSI- or ISO-specific functions, respectively.

@example
ESC E                           Next Line
ESC D                           Index
ESC M                           Reverse Index
ESC H                           Horizontal Tab Set
ESC Z                           Send VT100 Identification String
ESC 7                   (V)     Save Cursor and Attributes
ESC 8                   (V)     Restore Cursor and Attributes
ESC [s                  (A)     Save Cursor and Attributes
ESC [u                  (A)     Restore Cursor and Attributes
ESC c                           Reset to Initial State
ESC =                   (V)     Application Keypad Mode
ESC >                   (V)     Numeric Keypad Mode
ESC # 8                 (V)     Fill Screen with E's
ESC \                   (A)     String Terminator
ESC ^                   (A)     Privacy Message String (Message Line)
ESC !                           Global Message String (Message Line)
ESC k                           Title Definition String
ESC P                   (A)     Device Control String
                                Outputs a string directly to the host
                                terminal without interpretation.
ESC _                   (A)     Application Program Command (not used)
ESC ]                   (A)     Operating System Command (not used)
Control-N               (A)     Lock Shift G1 (SO)
Control-O               (A)     Lock Shift G0 (SI)
ESC n                   (A)     Lock Shift G2
ESC o                   (A)     Lock Shift G3
ESC N                   (A)     Single Shift G2
ESC O                   (A)     Single Shift G3
ESC ( Pcs               (A)     Designate character set as G0
ESC ) Pcs               (A)     Designate character set as G1
ESC * Pcs               (A)     Designate character set as G2
ESC + Pcs               (A)     Designate character set as G3
ESC [ Pn ; Pn H                 Direct Cursor Addressing
ESC [ Pn ; Pn f                 Direct Cursor Addressing
ESC [ Pn J                      Erase in Display
      Pn = None or 0            From Cursor to End of Screen
           1                    From Beginning of Screen to Cursor
           2                    Entire Screen
ESC [ Pn K                      Erase in Line
      Pn = None or 0            From Cursor to End of Line
           1                    From Beginning of Line to Cursor
           2                    Entire Line
ESC [ Pn A                      Cursor Up
ESC [ Pn B                      Cursor Down
ESC [ Pn C                      Cursor Right
ESC [ Pn D                      Cursor Left
ESC [ Ps ;...; Ps m             Select Graphic Rendition
      Ps = None or 0            Default Rendition
           1                    Bold
           2            (A)     Faint
           3            (A)     @i{Standout} Mode (ANSI: Italicized)
           4                    Underlined
           5                    Blinking
           7                    Negative Image
           22           (A)     Normal Intensity
           23           (A)     @i{Standout} Mode off (ANSI: Italicized off)
           24           (A)     Not Underlined
           25           (A)     Not Blinking
           27           (A)     Positive Image
ESC [ Pn g                      Tab Clear
      Pn = None or 0            Clear Tab at Current Position
           3                    Clear All Tabs
ESC [ Pn ; Pn r         (V)     Set Scrolling Region
ESC [ Pn I              (A)     Horizontal Tab
ESC [ Pn Z              (A)     Backward Tab
ESC [ Pn L              (A)     Insert Line
ESC [ Pn M              (A)     Delete Line
ESC [ Pn @@              (A)     Insert Character
ESC [ Pn P              (A)     Delete Character
ESC [ Ps ;...; Ps h             Set Mode
ESC [ Ps ;...; Ps l             Reset Mode
      Ps = 4            (A)     Insert Mode
           ?1           (V)     Application Cursor Keys
           ?3           (V)     Change Terminal Width to 132 columns
           ?5           (V)     Visible Bell (@samp{On} followed by @samp{Off})
           ?6           (V)     @samp{Origin} Mode
           ?7           (V)     @samp{Wrap} Mode
ESC [ 5 i               (A)     Start relay to printer (ANSI Media Copy)
ESC [ 4 i               (A)     Stop relay to printer (ANSI Media Copy)
ESC [ 8 ; Ph ; Pw t             Resize the window to @samp{Ph} lines and
                                @samp{Pw} columns (SunView special)
ESC [ c                         Send VT100 Identification String
ESC [ 6 n                       Send Cursor Position Report
@end example

@node Bell, Clear, Control Sequences, Virtual Terminal
@section Bell

@deffn Command bell message
(none)@*
When a bell character is sent to a background window, @code{screen}
displays a notification in the message line.  The notification message
can be re-defined by means of the @code{bell} command.  Each occurrence
of @samp{%} in @var{message} is replaced by the number of the window to
which a bell has been sent, and each occurrence of @samp{~} is replaced
by the definition for bell in your termcap (usually an audible bell).
The default message is

@example
'Bell in window %'
@end example

An empty message can be supplied to the @code{bell} command to suppress
output of a message line (@code{bell ""}).
@end deffn

@kindex C-g
@deffn Command vbell [state]
(@kbd{C-a C-g})@*
Sets or toggles the visual bell setting for the current window. If your
terminal does not support a visual bell, the visual bell message is
displayed in the status line.  @xref{Bell, , Visual Bell, termcap, The
Termcap Manual}, for more information on visual bells.  The equivalent
terminfo capability is @code{flash}.
@end deffn

@deffn Command vbell_msg message
(none)@*
Sets the visual bell message. @var{message} is printed to the status
line if the window receives a bell character (^G) and @code{vbell} is
set to @samp{on}.  The default message is @samp{Wuff, Wuff!!}.
@end deffn

@deffn Command vbellwait sec
(none)@*
Define a delay in seconds after each display of @code{screen} 's visual
bell message. The default is 1 second.
@end deffn

@node Clear, Height, Bell, Virtual Terminal
@section Clear
@kindex C
@deffn Command clear
(@kbd{C-a C})@*
Clears the screen and saves its contents to the scrollback buffer.
@end deffn

@node Height, Info, Clear, Virtual Terminal
@section Height
@deffn Command height @var{[lines]}
(none)@*
Set the display height to a specified number of lines. When no
argument is given it toggles between 24 and 42 lines display.
@end deffn

@node Info, Redisplay, Height, Virtual Terminal
@section Info
@kindex i
@kindex C-i
@deffn Command info
(@kbd{C-a i}, @kbd{C-a C-i})@*
Uses the message line to display some information about the current
window: the cursor position in the form @samp{(@var{column},@var{row})}
starting with @samp{(1,1)}, the terminal width and height plus the size
of the scrollback buffer in lines, like in @samp{(80,24)+50}, various
flag settings (flow-control, insert mode, origin mode, wrap mode,
application-keypad mode, output logging, activity monitoring, and redraw
(@samp{+} indicates enabled, @samp{-} not)), the currently active
character set (@samp{G0}, @samp{G1}, @samp{G2}, or @samp{G3}), and in
square brackets the terminal character sets that are currently
designated as @samp{G0} through @samp{G3}.  For system information use
@code{time}.
@end deffn

@node Redisplay, Wrap, Info, Virtual Terminal
@section Redisplay

@deffn Command allpartial state
(none)@*
If set to on, only the current cursor line is refreshed on window change.
This affects all windows and is useful for slow terminal lines. The 
previous setting of full/partial refresh for each window is restored
with @code{allpartial off}.
@end deffn

@deffn Command partial state
(none)@*
Defines whether the display should be refreshed (as with
@code{redisplay}) after switching to the current window. This command
only affects the current window.  To affect all windows use the
@code{allpartial} command.  Default is @samp{off}, of course.
@end deffn

@kindex l
@kindex C-l
@deffn Command redisplay
(@kbd{C-a l}, @kbd{C-a C-l})@*
Redisplay the current window.  Needed to get a full redisplay in
partial redraw mode.
@end deffn

@node Wrap, Reset, Redisplay, Virtual Terminal
@section Wrap

@kindex r
@kindex C-r
@deffn Command wrap state
(@kbd{C-a r}, @kbd{C-a C-r}) @*
Sets the line-wrap setting for the current window.  When line-wrap is
on, the second consecutive printable character output at the last column
of a line will wrap to the start of the following line.  As an added
feature, backspace (^H) will also wrap through the left margin to the
previous line.  Default is @samp{on}.
@end deffn

@deffn Command defwrap state
(none) @*
Same as the @code{wrap} command except that the default setting for new 
windows is changed. Initially line-wrap is on and can be toggled with the 
@code{wrap} command (@kbd{C-a r}) or by means of "C-a : wrap on|off".
@end deffn

@node Reset, Width, Wrap, Virtual Terminal
@section Reset
@kindex Z
@deffn Command reset
(@kbd{C-a Z})@*
Reset the virtual terminal to its ``power-on'' values. Useful when strange
settings (like scroll regions or graphics character set) are left over from
an application.
@end deffn

@node Width,  , Reset, Virtual Terminal
@section Width
@kindex W
@deffn Command width [num]
(@kbd{C-a W})@*
Toggle the window width between 80 and 132 columns, or set it to
@var{num} columns if an argument is specified.  This requires a
capable terminal and the termcap entries @samp{Z0} and @samp{Z1}.  See
the @code{termcap} command (@pxref{Termcap}), for more information.
@end deffn

@node Copy and Paste, Subprocess Execution, Virtual Terminal, Top
@chapter Copy and Paste
@cindex copy and paste

For those confined to a hardware terminal, these commands provide a cut
and paste facility more powerful than those provided by most windowing
systems.

@menu
* Copy::                        Copy from scrollback to buffer
* Paste::                       Paste from buffer into window
* Registers::                   Longer-term storage
* Screen-Exchange::             Sharing data between screen users
* History::                     Recalling previous input
@end menu

@node Copy, Paste,  , Copy and Paste
@section Copying
@cindex marking
@cindex scrollback
@kindex [
@kindex C-[
@kindex ESC
@deffn Command copy
(@kbd{C-a [}, @kbd{C-a C-[}, @kbd{C-a @key{ESC}})@*
Enter copy/scrollback mode. This allows you to copy text from the
current window and its history into the paste buffer. In this mode a
@code{vi}-like full screen editor is active, with controls as
outlined below.
@end deffn

@menu
* Line Termination::            End copied lines with CR/LF
* Scrollback::                  Set the size of the scrollback buffer
* Copy Mode Keys::              Remap keys in copy mode
* Movement::                    Move around in the scrollback buffer
* Marking::                     Select the text you want
* Repeat count::                Repeat a command
* Searching::                   Find the text you want
* Specials::                    Other random keys
@end menu

@node Line Termination, Scrollback,  , Copy
@subsection CR/LF
@deffn Command crlf state
(none)@*
This affects the copying of text regions with the @kbd{C-a [} command.
If it is set to @samp{on}, lines will be separated by the two character
sequence @samp{CR}/@samp{LF}.  Otherwise only @samp{LF} is used.
@code{crlf} is off by default.
@end deffn

@node Scrollback, Copy Mode Keys, Line Termination, Copy
@subsection Scrollback
@deffn Command defscrollback num
(none)@*
Same as the @code{scrollback} command except that the default setting
for new windows is changed.  Defaults to 100.
@end deffn

@deffn Command scrollback num
(none)@*
Set the size of the scrollback buffer for new windows to @var{num}
lines.  The default scrollback is 100 lines.  Use @kbd{C-a i} to view
the current setting.
@end deffn

@node Copy Mode Keys, Movement, Scrollback, Copy
@subsection markkeys
@deffn Command markkeys string
(none)@*
This is a method of changing the keymap used for copy/history mode.  The
string is made up of @var{oldchar}=@var{newchar} pairs which are
separated by @samp{:}. Example: The command @code{markkeys
h=^B:l=^F:$=^E} would set some keys to be more familiar to @code{emacs}
users.
@end deffn

@node Movement, Marking, Copy Mode Keys, Copy
@subsection Movement Keys

@noindent
@kbd{h}, @kbd{j}, @kbd{k}, @kbd{l} move the cursor line by line or
column by column.

@noindent
@kbd{0}, @kbd{^} and @kbd{$} move to the leftmost column or to the first
or last non-whitespace character on the line.

@noindent
@kbd{H}, @kbd{M} and @kbd{L} move the cursor to the leftmost column
of the top, center or bottom line of the window. 

@noindent
@kbd{+} and @kbd{-} move the cursor to the leftmost column of the next
or previous line.

@noindent
@kbd{G} moves to the specified absolute line (default: end of buffer).
 
@noindent
@kbd{|} moves to the specified absolute column.

@noindent
@kbd{w}, @kbd{b}, @kbd{e} move the cursor word by word.
 
@noindent
@kbd{C-u} and @kbd{C-d} scroll the display up/down by the specified
amount of lines while preserving the cursor position. (Default: half
screenfull).

@noindent
@kbd{C-b} and @kbd{C-f} move the cursor up/down a full screen.

@noindent
@kbd{g} moves to the beginning of the buffer.

@noindent
@kbd{%} jumps to the specified percentage of the buffer.

Note that Emacs-style movement keys can be specified by a .screenrc
command. (@code{markkeys "h=^B:l=^F:$=^E"}) There is no simple method for
a full emacs-style keymap, however, as this involves multi-character codes.

@node Marking, Repeat count, Movement, Copy
@subsection Marking

The copy range is specified by setting two marks. The text between these
marks will be highlighted. Press @kbd{space} to set the first or second
mark respectively.

@noindent
@kbd{Y} and @kbd{y} can be used to mark one whole line or to mark from 
start of line.

@noindent
@kbd{W} marks exactly one word. 
 
@node Repeat count, Searching, Marking, Copy
@subsection Repeat Count

Any command in copy mode can be prefixed with a number (by pressing
digits @kbd{0@dots{}9}) which is taken as a repeat count. Example:
@kbd{C-a C-[ H 10 j 5 Y} will copy lines 11 to 15 into the pastebuffer.

@node Searching, Specials, Repeat count, Copy
@subsection Searching

@noindent
@kbd{/} @code{vi}-like search forward.

@noindent
@kbd{?} @code{vi}-like search backward.

@noindent
@kbd{C-a s} @code{emacs} style incremental search forward.

@noindent
@kbd{C-r} @code{emacs} style reverse i-search.

@node Specials,  , Searching, Copy
@subsection Specials

There are, however, some keys that act differently here from in
@code{vi}.  @code{Vi} does not allow to yank rectangular blocks of text,
but @code{screen} does. Press

@noindent
@kbd{c} or @kbd{C} to set the left or right margin respectively. If no
repeat count is given, both default to the current cursor position.@*
Example: Try this on a rather full text screen: 
@kbd{C-a [ M 20 l SPACE c 10 l 5 j C SPACE}.

@noindent
This moves one to the middle line of the screen, moves in 20 columns left,
marks the beginning of the copybuffer, sets the left column, moves 5 columns
down, sets the right column, and then marks the end of
the copybuffer. Now try:@*
@kbd{C-a [ M 20 l SPACE 10 l 5 j SPACE}

@noindent
and notice the difference in the amount of text copied.

@noindent
@kbd{J} joins lines. It toggles between 3 modes: lines separated by a
newline character (012), lines glued seamless, or lines separated by a
single space. Note that you can prepend the newline character with
a carriage return character, by issuing a @code{set crlf on}.

@noindent
@kbd{v} is for all the @code{vi} users who use @code{:set numbers} - it
toggles the left margin between column 9 and 1.

@noindent
@kbd{a} before the final space key turns on append mode. Thus
the contents of the pastebuffer will not be overwritten, but appended to.

@noindent
@kbd{A} turns on append mode and sets a (second) mark.

@noindent
@kbd{>} sets the (second) mark and writes the contents of the copybuffer
to the screen-exchange file (@file{/tmp/screen-exchange} per default)
once copy-mode is finished.  @xref{Screen-Exchange}.@*
This example demonstrates how to dump the
whole scrollback buffer to that file: @*@kbd{C-a [ g SPACE G $ >}.

@noindent
@kbd{C-g} gives information about the current line and column.

@noindent
@kbd{@@} does nothing.  Absolutely nothing.  Does not even exit copy
mode.

@node Paste, Registers, Copy, Copy and Paste
@section Paste

@kindex ]
@kindex C-]
@deffn Command paste [registers]
(@kbd{C-a ]}, @kbd{C-a C-]})@*
Write the contents of the specified registers to the stdin stream of the
current window.  The register @samp{.} is treated as the
paste buffer. If no parameter is given only the paste buffer is used.
The paste buffer can be filled with the @code{copy},
@code{history} and @code{readbuf} commands.
@end deffn

@deffn Command slowpaste msec
(none)@*
Define the speed text is inserted by the @code{paste} command.
If the slowpaste value is nonzero text is written character by character.
@code{screen} will pause for @var{msec} milliseconds after each write
to allow the application to process the input. only use @code{slowpaste} if 
your underlying system exposes flow control problems while pasting large 
amounts of text.
@end deffn

@node Registers, Screen-Exchange, Paste, Copy and Paste
@section Registers

@deffn Command copy_reg [key]
(none)@*
Store the current copybuffer contents in a register referenced by @var{key}.
If the name is omitted you will be prompted to press the key.
@end deffn

@deffn Command ins_reg [key]
(none)@*
Paste contents of register @var{key} into the current window's input
stream.
@end deffn

@deffn Command process [key]
(none)@*
Stuff the contents of the specified register into the @code{screen}
input queue. If no argument is given you are prompted for a
register name. The text is parsed as if it had been typed in from the users
keyboard. This command can be used to bind multiple actions to a single key.
@end deffn

@deffn Command register key string
(none)@*
Save the specified @var{string} to the register @var{key}.
@end deffn

@node Screen-Exchange, History, Registers, Copy and Paste
@section Screen-Exchange

@deffn Command bufferfile [exchange-file]
(none)@*
Change the filename used for reading and writing with the copybuffer.
If the @var{exchange-file} parameter is omitted, @code{screen} reverts
to the default of @file{/tmp/screen-exchange}.  The following example
will paste the system's password file into the screen window:

@example
C-a : bufferfile /etc/passwd
C-a < C-a ]
@end example
@end deffn

@kindex <
@deffn Command readbuf
(@kbd{C-a <})@*
Reads the contents of the current screen-exchange file into the copy buffer. 
@end deffn

@kindex =
@deffn Command removebuf
(@kbd{C-a =})@*
Unlinks the screen-exchange file.
@end deffn

@kindex >
@deffn Command writebuf
(@kbd{C-a >})@*
Writes the contents of the paste buffer to a public accessible
screen-exchange file. This is thought of as a primitive means of
communication between @code{screen} users on the same host. See also
@kbd{C-a @key{ESC}} (@pxref{Copy}).
@end deffn

@node History,  , Screen-Exchange, Copy and Paste
@section History

@kindex @{
@deffn Command history
(@kbd{C-a @{})@*
Usually users work with a shell that allows easy access to previous
commands.  For example, @code{csh} has the command @code{!!} to repeat
the last command executed.  @code{screen} provides a primitive way of
recalling ``the command that started @dots{}'': You just type the first
letter of that command, then hit @kbd{C-a @{} and @code{screen} tries to
find a previous line that matches with the prompt character to the left
of the cursor. This line is pasted into this window's input queue.  Thus
you have a crude command history (made up by the visible window and its
scrollback buffer).
@end deffn

@node Subprocess Execution, Key Binding, Copy and Paste, Top
@chapter Subprocess Execution
Control Input or Output of a window by another filter process.
Use with care!

@menu
* Exec::                        The @code{exec} command syntax.
* Using Exec::                  Weird things that filters can do.
@end menu

@node Exec, Using Exec,  , Subprocess Execution
@section Exec
@deffn Command exec @var{[[fdpat] newcommand [args ... ]]}
(none)@*
Run a unix subprocess (specified by an executable path @var{newcommand} and 
its optional arguments) in the current window. The flow of data between
newcommands stdin/stdout/stderr, the process already running (shell) and 
screen itself (window) is controlled by the filedescriptor pattern @var{fdpat}.
This pattern is basically a three character sequence representing stdin, stdout
and stderr of newcommand. A dot (@code{.}) connects the file descriptor
to screen. An exclamation mark (@code{!}) causes the file descriptor to be
connected to the already running process. A colon (@code{:}) combines both.
@*
User input will go to newcommand unless newcommand requests the old process'
output (@var{fdpat}s first character is @samp{!} or @samp{:}) or a pipe symbol
(@samp{|}) is added to the end of @var{fdpat}.
@*
Invoking @code{exec} without arguments shows name and arguments of the currently
running subprocess in this window.
@*
When a subprocess is running the @code{kill} command will affect it instead of 
the windows process.
@*
Refer to the postscript file @file{doc/fdpat.ps} for illustration of all 21 
possible combinations. Each drawing shows the numbers 210 representing the three
file descriptors of newcommand. The box marked `W' is usual pty that has 
the old process (shell) on its slave side. The box marked `P' is the 
secondary pty that now has screen at its master side.
@end deffn

@node Using Exec,  , Exec, Subprocess Execution
@section Using Exec
@noindent 
Abbreviations:

@itemize @bullet
@item
Whitespace between the word @samp{exec} and @var{fdpat} and the command name
can be omitted. 

@item
Trailing dots and a @var{fdpat} consisting only of dots can be omitted. 

@item 
A simple @samp{|} is synonymous for the @samp{!..|} pattern.

@item
The word @samp{exec} can be ommitted when the @samp{|} abbreviation is used.

@item
The word @samp{exec} can always be replaced by leading @samp{!}.
@end itemize

@noindent 
Examples:

@table @code
@item !/bin/sh
@itemx exec /bin/sh
@itemx exec ... /bin/sh
Creates another shell in the same window, while the orignal shell is still 
running. Output of both shells is displayed and user input is sent to the new
@file{/bin/sh}.

@item !!stty 19200
@itemx exec!stty 19200
@itemx exec !.. stty 19200
Set the speed of the windows tty. If your stty command operates on stdout, then
add another @samp{!}. This is a useful command, when a screen window is 
directly connected to a serial line that needs to be configured.

@item |less
@itemx exec !..| less
This adds a pager to the window output. The special character @samp{|} is 
needed to give the user control over the pager although it gets its input from 
the windows process. This works, because @samp{less} listens on stderr 
(a behavior that @code{screen} would not expect without the @samp{|}) 
when its stdin is not a tty.

@item !:sed -n s/.*Error.*/\007/p
Sends window output to both, the user and the sed command. The sed inserts an
additional bell character (oct. 007) to the window output seen by screen.
This will cause 'Bell in window x' messages, whenever the string @samp{Error}
appears in the window.
@end table

@node Key Binding, Flow Control, Subprocess Execution, Top
@chapter Key Binding
@cindex key binding
@cindex binding

You may disagree with some of the default bindings (I know I do).  The
@code{bind} command allows you to redefine them to suit your
preferences.

@menu
* Bind::                        @code{bind} syntax.
* Bind Examples::               Using @code{bind}.
* Command Character::           The character used to start keyboard commands.
* Help::                        Show current key bindings.
@end menu

@node Bind, Bind Examples,  , Key Binding
@section The @code{bind} command
@deffn Command bind key [command [args]]
(none)@*
Bind a command to a key.  The @var{key} argument is either a single
character, a two-character sequence of the form @samp{^x} (meaning
@kbd{C-x}), a backslash followed by an octal number (specifying the
ASCII code of the character), or a backslash followed by a second
character, such as @samp{\^} or @samp{\\}.  The argument can also be
quoted, if you like.  If no further argument is given, any previously
established binding for this key is removed.  The @var{command}
argument can be any command (@pxref{Command Index}).

By default, most suitable commands are bound to one or more keys
(@pxref{Default Key Bindings}; for instance, the command to create a
new window is bound to @kbd{C-c} and @kbd{c}.  The @code{bind} command
can be used to redefine the key bindings and to define new bindings.
@end deffn

@node Bind Examples, Command Character, Bind, Key Binding
@section Examples of the @code{bind} command
@noindent
Some examples:

@example
bind ' ' windows
bind ^f screen telnet foobar
bind \033 screen -ln -t root -h 1000 9 su
@end example

@noindent
would bind the space key to the command that displays a list of windows
(so that the command usually invoked by @kbd{C-a C-w} would also be
available as @kbd{C-a space}), bind @kbd{C-f} to the command
``create a window with a TELNET connection to foobar'', and bind
@key{ESC} to the command that creates an non-login window with title
@samp{root} in slot #9, with a super-user shell and a scrollbackbuffer
of 1000 lines.

@node Command Character, Help, Bind Examples, Key Binding
@section Command Character

@deffn Command escape xy
(none)@*
Set the command character to @var{x} and the character generating a
literal command character to @var{y} (just like with the @samp{-e}
option).  Each argument is either a single character, a two-character
sequence of the form @samp{^x} (meaning @kbd{C-x}), a backslash followed
by an octal number (specifying the ASCII code of the character), or a
backslash followed by a second character, such as @samp{\^} or
@samp{\\}.  The default is @samp{^Aa}, but @samp{``} is recommended by
one of the authors.
@end deffn

@kindex a
@deffn Command meta
(@kbd{C-a a})@*
Send the command character (@kbd{C-a}) to the process in the current
window.  The keystroke for this command is the second parameter to the
@samp{-e} command line switch (@pxref{Invoking Screen}), or the
@code{escape} .screenrc directive.
@end deffn

@node Help,  , Command Character, Key Binding
@section Help
@kindex ?
@deffn Command help
(@kbd{C-a ?})@*
Displays a help screen showing you all the key bindings.  The first
pages list all the internal commands followed by their bindings.
Subsequent pages will display the custom commands, one command per key.
Press space when you're done reading each page, or return to exit early.
All other characters are ignored, except for the command character,
which will exit the help display and begin a command.  
@xref{Default Key Bindings}.
@end deffn

@node Flow Control, Termcap, Key Binding, Top
@chapter Flow Control
@cindex flow control

@code{screen} can trap flow control characters or pass them to the
program, as you see fit.  This is useful when your terminal wants to use
XON/XOFF flow control and you are running a program which wants to use
^S/^Q for other purposes (i.e. @code{emacs}).

@menu
* Flow Control Summary::        The effect of @code{screen} flow control
* Flow::                        Setting the flow control behavior
* XON/XOFF::                    Sending XON or XOFF to the window
@end menu

@node Flow Control Summary, Flow,  , Flow Control
@section About @code{screen} flow control settings
Each window has a flow-control setting that determines how screen deals
with the XON and XOFF characters (and perhaps the interrupt character).
When flow-control is turned off, screen ignores the XON and XOFF
characters, which allows the user to send them to the current program by
simply typing them (useful for the @code{emacs} editor, for instance).
The trade-off is that it will take longer for output from a
``normal'' program to pause in response to an XOFF.  With
flow-control turned on, XON and XOFF characters are used to immediately
pause the output of the current window.  You can still send these
characters to the current program, but you must use the appropriate
two-character screen commands (typically @kbd{C-a q} (xon) and @kbd{C-a
s} (xoff)).  The xon/xoff commands are also useful for typing C-s and
C-q past a terminal that intercepts these characters.

Each window has an initial flow-control value set with either the
@samp{-f} option or the @code{defflow} command.  By default the
windows are set to automatic flow-switching.  It can then be toggled
between the three states 'fixed on', 'fixed off' and 'automatic'
interactively with the @code{flow} command bound to @kbd{C-a f}.

The automatic flow-switching mode deals with flow control using the
TIOCPKT mode (like @code{rlogin} does). If the tty driver does not
support TIOCPKT, screen tries to determine the right mode based on the
current setting of the application keypad --- when it is enabled,
flow-control is turned off and visa versa.  Of course, you can still
manipulate flow-control manually when needed.

If you're running with flow-control enabled and find that pressing the
interrupt key (usually C-c) does not interrupt the display until another
6-8 lines have scrolled by, try running screen with the @samp{interrupt}
option (add the @samp{interrupt} flag to the @code{flow} command in your
.screenrc, or use the @samp{-i} command-line option).  This causes the
output that @code{screen} has accumulated from the interrupted program
to be flushed.  One disadvantage is that the virtual terminal's memory
contains the non-flushed version of the output, which in rare cases can
cause minor inaccuracies in the output.  For example, if you switch
screens and return, or update the screen with @kbd{C-a l} you would see
the version of the output you would have gotten without @samp{interrupt}
being on.  Also, you might need to turn off flow-control (or use
auto-flow mode to turn it off automatically) when running a program that
expects you to type the interrupt character as input, as the
@samp{interrupt} parameter only takes effect when flow-control is
enabled.  If your program's output is interrupted by mistake, a simple
refresh of the screen with @kbd{C-a l} will restore it.  Give each mode
a try, and use whichever mode you find more comfortable.

@node Flow, XON/XOFF, Flow Control Summary, Flow Control
@section Flow
@deffn Command defflow fstate [interrupt]
(none)@*
Same as the @code{flow} command except that the default setting for new
windows is changed. Initial setting is `auto'.
Specifying @code{flow auto
interrupt} has the same effect as the command-line options @samp{-fa}
and @samp{-i}.
@end deffn

@kindex f
@kindex C-f
@deffn Command flow [fstate]
(@kbd{C-a f}, @kbd{C-a C-f})@*
Sets the flow-control mode for this window to @var{fstate}, which can be
@samp{on}, @samp{off} or @samp{auto}.
Without parameters it cycles the current window's
flow-control setting.  Default is set by `defflow'.
@end deffn

@node XON/XOFF,  , Flow, Flow Control
@section XON and XOFF
@kindex q
@kindex C-q
@deffn Command xon
(@kbd{C-a q}, @kbd{C-a C-q})@*
Send a ^Q (ASCII XON) to the program in the current window.  Redundant
if flow control is set to @samp{off} or @samp{auto}.
@end deffn

@kindex s
@kindex C-s
@deffn Command xoff
(@kbd{C-a s}, @kbd{C-a C-s})@*
Send a ^S (ASCII XOFF) to the program in the current window.
@end deffn

@node Termcap, Message Line, Flow Control, Top
@chapter Termcap

@code{screen} demands the most out of your terminal so that it can
perform its VT100 emulation most efficiently.  These functions provide
means for tweaking the termcap entries for both your physical terminal
and the one simulated by @code{screen}.

@menu
* Window Termcap::              Choosing a termcap entry for the window.
* Dump Termcap::                Write out a termcap entry for the window.
* Termcap Syntax::              The @code{termcap} and @code{terminfo} commands.
* Termcap Examples::            Uses for @code{termcap}.
* Special Capabilities::        Non-standard capabilities used by @code{screen}.
@end menu

@node Window Termcap, Dump Termcap,  , Termcap
@section Choosing the termcap entry for a window
Usually @code{screen} tries to emulate as much of the VT100/ANSI
standard as possible. But if your terminal lacks certain capabilities
the emulation may not be complete. In these cases @code{screen} has to
tell the applications that some of the features are missing. This is no
problem on machines using termcap, because @code{screen} can use the
@code{$TERMCAP} variable to customize the standard screen termcap.

But if you do a rlogin on another machine or your machine supports only
terminfo this method fails. Because of this @code{screen} offers a way
to deal with these cases. Here is how it works:

When @code{screen} tries to figure out a terminal name for itself, it
first looks for an entry named @samp{screen.@var{term}}, where
@var{term} is the contents of your @code{$TERM} variable.  If no such entry
exists, @code{screen} tries @samp{screen} (or @samp{screen-w}, if the
terminal is wide (132 cols or more)).  If even this entry cannot be
found, @samp{vt100} is used as a substitute.

The idea is that if you have a terminal which doesn't support an
important feature (e.g. delete char or clear to EOS) you can build a new
termcap/terminfo entry for @code{screen} (named
@samp{screen.@var{dumbterm}}) in which this capability has been
disabled.  If this entry is installed on your machines you are able to
do a rlogin and still keep the correct termcap/terminfo entry.  The
terminal name is put in the @code{$TERM} variable of all new windows.
@code{screen} also sets the @code{$TERMCAP} variable reflecting the
capabilities of the virtual terminal emulated. 
Furthermore, the variable @code{$WINDOW} is set to the window number of each
window.

The actual set of capabilities supported by the virtual terminal depends
on the capabilities supported by the physical terminal.  If, for
instance, the physical terminal does not support underscore mode,
@code{screen} does not put the @samp{us} and @samp{ue} capabilities into
the window's @code{$TERMCAP} variable, accordingly.  However, a minimum number
of capabilities must be supported by a terminal in order to run
@code{screen}; namely scrolling, clear screen, and direct cursor
addressing (in addition, @code{screen} does not run on hardcopy
terminals or on terminals that over-strike).

Also, you can customize the @code{$TERMCAP} value used by @code{screen} by
using the @code{termcap} command, or by defining the variable
@code{$SCREENCAP} prior to startup.  When the latter defined, its value will be
copied verbatim into each window's @code{$TERMCAP} variable.  This can either
be the full terminal definition, or a filename where the terminal
@samp{screen} (and/or @samp{screen-w}) is defined.

Note that @code{screen} honors the @code{terminfo} command if the system
uses the terminfo database rather than termcap.  On such machines the
@code{$TERMCAP} variable has no effect and you must use the
@code{dumptermcap} command (@pxref{Dump Termcap}) and the @code{tic}
program to generate terminfo entries for @code{screen} windows.

When the boolean @samp{G0} capability is present in the termcap entry
for the terminal on which @code{screen} has been called, the terminal
emulation of @code{screen} supports multiple character sets.  This
allows an application to make use of, for instance, the VT100 graphics
character set or national character sets.  The following control
functions from ISO 2022 are supported: @samp{lock shift G0} (@samp{SI}),
@samp{lock shift G1} (@samp{SO}), @samp{lock shift G2}, @samp{lock shift
G3}, @samp{single shift G2}, and @samp{single shift G3}.  When a virtual
terminal is created or reset, the ASCII character set is designated as
@samp{G0} through @samp{G3}.  When the @samp{G0} capability is present,
screen evaluates the capabilities @samp{S0}, @samp{E0}, and @samp{C0} if
present. @samp{S0} is the sequence the terminal uses to enable and start
the graphics character set rather than @samp{SI}.  @samp{E0} is the
corresponding replacement for @samp{SO}. @samp{C0} gives a character by
character translation string that is used during semi-graphics mode.
This string is built like the @samp{acsc} terminfo capability.

When the @samp{po} and @samp{pf} capabilities are present in the
terminal's termcap entry, applications running in a @code{screen} window
can send output to the printer port of the terminal.  This allows a user
to have an application in one window sending output to a printer
connected to the terminal, while all other windows are still active (the
printer port is enabled and disabled again for each chunk of output).
As a side-effect, programs running in different windows can send output
to the printer simultaneously.  Data sent to the printer is not
displayed in the window.

Some capabilities are only put into the @code{$TERMCAP} variable of the virtual
terminal if they can be efficiently implemented by the physical
terminal.  For instance, @samp{dl} (delete line) is only put into the
@code{$TERMCAP} variable if the terminal supports either delete line itself or
scrolling regions. Note that this may provoke confusion, when the
session is reattached on a different terminal, as the value of @code{$TERMCAP}
cannot be modified by parent processes.  You can force @code{screen} to
include all capabilities in @code{$TERMCAP} with the @samp{-a}
command-line option (@pxref{Invoking Screen}).

@node Dump Termcap, Termcap Syntax, Window Termcap, Termcap
@section Write out the window's termcap entry
@kindex .
@deffn Command dumptermcap
(@kbd{C-a .})@*
Write the termcap entry for the virtual terminal optimized for the
currently active window to the file @file{.termcap} in the user's
@file{$HOME/.screen} directory (or wherever @code{screen} stores its
sockets. @pxref{Files}).  This termcap entry is identical to
the value of the environment variable @code{$TERMCAP} that is set up by
@code{screen} for each window. For terminfo based systems you will need
to run a converter like @code{captoinfo} and then compile the entry with
@code{tic}.
@end deffn

@node Termcap Syntax, Termcap Examples, Dump Termcap, Termcap
@section The @code{termcap} command
@deffn Command termcap term terminal-tweaks [window-tweaks]
@deffnx Command terminfo term terminal-tweaks [window-tweaks]
(none)@*
Use this command to modify your terminal's termcap entry without going
through all the hassles involved in creating a custom termcap entry.
Plus, you can optionally customize the termcap generated for the
windows.  If your system uses the terminfo database rather than
termcap, @code{screen} will understand the @code{terminfo} command which
has the same effects as the @code{termcap} command. Thus users can write
one .screenrc file that handles both cases, although terminfo syntax is
slightly different from termcap syntax.
@end deffn

The first argument specifies which terminal(s) should be affected by
this definition.  You can specify multiple terminal names by separating
them with @samp{|}s.  Use @samp{*} to match all terminals and @samp{vt*}
to match all terminals that begin with @samp{vt}.

Each @var{tweak} argument contains one or more termcap defines
(separated by @samp{:}s) to be inserted at the start of the appropriate
termcap entry, enhancing it or overriding existing values.  The first
tweak modifies your terminal's termcap, and contains definitions that
your terminal uses to perform certain functions.  Specify a null string
to leave this unchanged (e.g. "").  The second (optional) tweak modifies
all the window termcaps, and should contain definitions that screen
understands (@pxref{Virtual Terminal}).

@node Termcap Examples, Special Capabilities, Termcap Syntax, Termcap
@section Termcap Examples
Some examples:

@example
termcap xterm*  xn:hs@@
@end example

@noindent
Informs @code{screen} that all terminals that begin with @samp{xterm}
have firm auto-margins that allow the last position on the screen to be
updated (xn), but they don't really have a status line (no 'hs' --
append @samp{@@} to turn entries off).  Note that we assume @samp{xn} for
all terminal names that start with @samp{vt}, but only if you don't
specify a termcap command for that terminal.

@example
termcap vt*  xn
termcap vt102|vt220  Z0=\E[?3h:Z1=\E[?3l
@end example

@noindent
Specifies the firm-margined @samp{xn} capability for all terminals that
begin with @samp{vt}, and the second line will also add the
escape-sequences to switch into (Z0) and back out of (Z1)
132-character-per-line mode if this is a vt102 or vt220.  (You must
specify Z0 and Z1 in your termcap to use the width-changing commands.)

@example
termcap vt100  ""  l0=PF1:l1=PF2:l2=PF3:l3=PF4
@end example

@noindent
This leaves your vt100 termcap alone and adds the function key labels to
each window's termcap entry.

@example
termcap h19|z19  am@@:im=\E@@:ei=\EO  dc=\E[P
@end example

@noindent
Takes a h19 or z19 termcap and turns off auto-margins (am@@) and enables
the insert mode (im) and end-insert (ei) capabilities (the @samp{@@} in
the @samp{im} string is after the @samp{=}, so it is part of the
string).  Having the @samp{im} and @samp{ei} definitions put into your
terminal's termcap will cause screen to automatically advertise the
character-insert capability in each window's termcap.  Each window will
also get the delete-character capability (dc) added to its termcap,
which screen will translate into a line-update for the terminal (we're
pretending it doesn't support character deletion).

If you would like to fully specify each window's termcap entry, you
should instead set the @code{$SCREENCAP} variable prior to running
@code{screen}.  @xref{Virtual Terminal}, for the details of the
@code{screen} terminal emulation.  @xref{Top, , Termcap, termcap, The
Termcap Manual}, for more information on termcap definitions.

@node Special Capabilities,  , Termcap Examples, Termcap
@section Special Terminal Capabilities
@cindex terminal capabilities
@cindex capabilities 
The following table describes all terminal capabilities that are
recognized by @code{screen} and are not in the termcap manual
(@pxref{Top, , Termcap, termcap, The Termcap Manual}).

@table @samp
@item LP
(bool)@*
Terminal has vt100 style margins (`magic margins'). Note that
this capability is obsolete --- @code{screen} now uses @samp{xn}
instead.

@item Z0
(str)@*
Change width to 132 columns.

@item Z1
(str)@*
Change width to 80 columns.

@item WS
(str)@*
Resize display. This capability has the desired width and height as
arguments.  SunView(tm) example: @samp{\E[8;%d;%dt}.

@item B8
(str)@*
Tell @code{screen} to look out for characters with 8th bit set. If such
a character is found @code{screen} processes the specified string
and than outputs the character with the 8th bit stripped off.
Note that the string can contain any esc-sequences known to
@code{screen}, too. (Example: Single Shift G2 = \EN.)

@item OP
(bool)@*
Don't do full vt100-style margin emulation. Same as the -O option.

@item NF
(bool)@*
Terminal doesn't need flow control. Send ^S and ^Q direct to
the application. Same as @code{flow off}. The opposite of this
capability is @samp{xo}.

@item G0
(bool)@*
Terminal can deal with ISO2022 font selection sequences.

@item S0
(str)@*
Switch charset @samp{G0} to the specified charset. Default
is @samp{\E(%d}.

@item E0
(str)@*
Switch charset @samp{G0} back to standard charset. Default
is @samp{\E(B}.

@item C0
(str)@*
Use the string as a conversion table for font 0. See
the @samp{ac} capability for more details.

@item CS
(str)@*
Switch cursor keys to application mode.

@item CE
(str)@*
Switch cursor keys to cursor mode.
@end table

@node Message Line, Logging, Termcap, Top
@chapter The Message Line
@cindex message line

@code{screen} displays informational messages and other diagnostics in a
@dfn{message line} at the bottom of the screen.  If your terminal has a
status line defined in its termcap, screen will use this for displaying
its messages, otherwise the last line of the screen will be temporarily
overwritten and output will be momentarily interrupted.  The message
line is automatically removed after a few seconds delay, but it can also
be removed early (on terminals without a status line) by beginning to
type.

@menu
* Privacy Message::             Using the message line from your program.
* Hardware Status Line::        Use the terminal's hardware status line.
* Last Message::                Redisplay the last message.
* Message Wait::                Control how long messages are displayed.
@end menu

@node Privacy Message, Hardware Status Line,  , Message Line
@section Using the message line from your program
The message line facility can be used by an application running in the
current window by means of the ANSI @dfn{Privacy message} control
sequence.  For instance, from within the shell, try something like:

@example
echo "@value{esc}^Hello world from window $WINDOW@value{esc}\"
@end example

where @samp{@value{esc}} is ASCII ESC and @samp{^} is a literal caret or
up-arrow.

@node Hardware Status Line, Last Message, Privacy Message, Message Line
@section Hardware Status Line
@deffn Command hardstatus [state]
(none)@*
Toggles the use of the terminal's hardware status line. If @samp{on},
@code{screen} will use this facility to display one line messages.
Otherwise these messages are overlayed in reverse video mode at the
display line. Note that the hardstatus feature can only be used if the
termcap/terminfo capabilities "hs", "ts", "fs" and "ds" are set
properly.  Default is @samp{on} whenever the "hs" capability is present.
@end deffn

@node Last Message, Message Wait, Hardware Status Line, Message Line
@section Display Last Message
@kindex m
@kindex C-m
@deffn Command lastmsg
(@kbd{C-a m}, @kbd{C-a C-m})@*
Repeat the last message displayed in the message line.  Useful if you're
typing when a message appears, because (unless your terminal has a
hardware status line) the message goes away when you press a key.
@end deffn

@node Message Wait,  , Last Message, Message Line
@section Message Wait
@deffn Command msgminwait sec
(none)@*
Defines the time @code{screen} delays a new message when another is
currently displayed.  Defaults to 1 second.
@end deffn

@deffn Command msgwait sec
(none)@*
Defines the time a message is displayed, if @code{screen} is not
disturbed by other activity.  Defaults to 5 seconds.
@end deffn

@node Logging, Startup, Message Line, Top
@chapter Logging

This section describes the commands for keeping a record of your session.

@menu
* Hardcopy::                    Dump the current screen to a file
* Log::                         Log the output of a window to a file
@end menu

@node Hardcopy, Log,  , Logging
@section hardcopy
@kindex h
@kindex C-h
@deffn Command hardcopy
(@kbd{C-a h}, @kbd{C-a C-h})@*
Writes out the current display contents to the file @file{hardcopy.@var{n}}
in the window's default directory, where @var{n} is the number of the
current window.  This either appends or overwrites the file if it
exists, as determined by the @code{hardcopy_append} command.
@end deffn

@deffn Command hardcopy_append state
(none)@*
If set to @samp{on}, @code{screen} will append to the
@file{hardcopy.@var{n}} files created by the command @code{hardcopy};
otherwise, these files are overwritten each time.
@end deffn

@deffn Comand hardcopydir directory
(none)@*
Defines a directory where hardcopy files will be placed.
If unset hardcopys are dumped in screens current working
directory.
@end deffn

@node Log,  , Hardcopy, Logging
@section log
@kindex H
@deffn Command log [state]
(@kbd{C-a H})@*
Begins/ends logging of the current window to the file
@file{screenlog.@var{n}} in the window's default directory, where
@var{n} is the number of the current window.  If no parameter is given,
the logging state is toggled.  The session log is
appended to the previous contents of the file if it already exists.  The
current contents and the contents of the scrollback history are not
included in the session log.  Default is @samp{off}.
@end deffn

@deffn Comand logdir directory
(none)@*
Defines a directory where logfiles will be placed. If unset logfiles
are written in @code{screen}s current working directory.
@end deffn

@node Startup, Miscellaneous, Logging, Top
@chapter Startup

This section describes commands which are only useful in the
@file{.screenrc} file, for use at startup.

@menu
* echo::                        Display a message.
* sleep::                       Pause execution of the @file{.screenrc}.
* Startup Message::             Control display of the copyright notice.
@end menu

@node echo, sleep,  , Startup
@section echo
@deffn Command echo [@t{-n}] message
(none)@*
The echo command may be used to annoy @code{screen} users with a
'message of the day'. Typically installed in a global screenrc. See also
@code{sleep}.  Echo is also useful for online checking of environment
variables.
@end deffn

@node sleep, Startup Message, echo, Startup
@section sleep
@deffn Command sleep num
(none)@*
This command will pause the execution of a .screenrc file for @var{num}
seconds.  Keyboard activity will end the sleep.  It may be used to give
users a chance to read the messages output by @code{echo}.
@end deffn

@node Startup Message,  , sleep, Startup
@section Startup Message
@deffn Command startup_message state
(none)@*
Select whether you want to see the copyright notice during startup.
Default is @samp{on}, as you probably noticed.
@end deffn

@node Miscellaneous, Environment, Startup, Top
@chapter Miscellaneous commands

The commands described here do not fit well under any of the other
categories.

@menu
* At::                          Execute a command at other displays or windows.
* Break::                       Send a break signal to the window.
* Debug::                       Suppress/allow debugging output.
* License::                     Display the disclaimer page.
* Nethack::                     Use @code{nethack}-like error messages.
* Number::                      Change the current window's number.
* Silence::			Notify on inactivity.
* Time::                        Display the time and load average.
* Version::                     Display the version of @code{screen}.
* Zombie::                      Keep dead windows.
@end menu

@node At, Break,  , Miscellaneous
@section At
@deffn Command at [identifier][#|*|%] command [args]
(none)@*
Execute a command at other displays or windows as if it had been entered there.
@code{At} changes the context (the `current window' or `current display'
setting) of the command. If the first parameter describes a non-unique context,
the command will be executed multiple times. If the first parameter is of the 
form @samp{@var{identifier}*} then identifier is matched against user names.
The command is executed once for each display of the selected user(s).
If the first parameter is of the form @samp{@var{identifier}%} identifier is
matched against displays. Displays are named after the ttys they attach. The
prefix @samp{/dev/} or @samp{/dev/tty} may be ommited from the identifier.
If @var{identifier} has a @code{#} or nothing appended it is matched against
window numbers and titles. Omitting an identifier in front of the @code{#},
@code{*} or @code{%} character selects all users, displays or windows because
a prefix-match is performed. Note that on the affected display(s) a short
message will describe what happened.
@end deffn

@node Break, Debug, At, Miscellaneous
@section Break
@deffn Command break [duration]
(none)@*
Send a break signal for @var{duration}*0.25 seconds to this window.
Most useful if a character device is attached to the window rather than
a shell process.
@end deffn

@deffn Command pow_break
(none)@*
Reopen the window's terminal line and send a break condition.
@end deffn

@node Debug, License, Break, Miscellaneous
@section Debug
@deffn Command debug [on|off]
(none)@*
Turns runtime debugging on or off. If @code{screen} has been compiled with
option @code{-DDEBUG} debugging is available and is turned on per default.
Note that this command only affects debugging output from the main 
@samp{SCREEN} process.
@end deffn

@node License, Nethack, Debug, Miscellaneous
@section License
@deffn Command license
(none)@*
Display the disclaimer page. This is done whenever @code{screen} is
started without options, which should be often enough.
@end deffn

@node Nethack, Number, License, Miscellaneous
@section Nethack
@deffn Command nethack state
(none)@*
Changes the kind of error messages used by @code{screen}.  When you are
familiar with the game @code{nethack}, you may enjoy the nethack-style
messages which will often blur the facts a little, but are much funnier
to read. Anyway, standard messages often tend to be unclear as well.

This option is only available if @code{screen} was compiled with the
NETHACK flag defined (@pxref{Installation}). The default setting is then
determined by the presence of the environment variable
@code{$NETHACKOPTIONS}.
@end deffn

@node Number, Silence, Nethack, Miscellaneous
@section Number
@kindex N
@deffn Command number @var{[n]}
(@kbd{C-a N})@*
Change the current window's number. If the given number @var{n} is already
used by another window, both windows exchange their numbers. If no argument is
specified, the current window number (and title) is shown.
@end deffn

@node Silence, Time, Number, Miscellaneous
@section Silence
@deffn Command silence @var{[state|sec]}
(none)@*
Toggles silence monitoring of windows. When silence is turned on and an 
affected window is switched into the background, you will receive the
silence notification message in the status line after a specified period
of inactivity (silence). The default timeout can be changed with the
@code{silencewait} command or by specifying a number of seconds instead of
@code{on} or @code{off}. Silence is initially off for all windows.
@end deffn

@deffn Command silencewait @var{seconds}
(none)@*
Define the time that all windows monitored for silence should wait
before displaying a message. Default is 30 seconds.
@end deffn

@node Time, Version, Silence, Miscellaneous
@section Time
@kindex t
@kindex C-t
@deffn Command time
(@kbd{C-a t}, @kbd{C-a C-t})@*
Uses the message line to display the time of day, the host name, and the
load averages over 1, 5, and 15 minutes (if this is available on your
system).  For window-specific information use @code{info} (@pxref{Info}).
@end deffn

@node Version, Zombie, Time, Miscellaneous
@section Version
@kindex v
@kindex C-v
@deffn Command version
(@kbd{C-a v}, @kbd{C-a C-v})@*
Display the version and modification date in the message line.
@end deffn

@node Zombie,  , Version, Miscellaneous
@section Zombie
@deffn Command zombie @var{[key]}
Per default windows are removed from the window list as soon as the
window's process (e.g. shell) exits. When a key is specified to the
zombie command a `dead' windows will remain in the list until it is selected
and this key is pressed or the @code{kill} command is issued.
@end deffn

@node Environment, Files, Miscellaneous, Top
@chapter Environment Variables
@cindex environment

@table @code
@item COLUMNS
Number of columns on the terminal (overrides termcap entry).

@item HOME
Directory in which to look for .screenrc.

@item ISCREENRC
Alternate user screenrc file.

@item LINES
Number of lines on the terminal (overrides termcap entry).

@item LOCKPRG
Screen lock program.

@item NETHACKOPTIONS
Turns on @code{nethack} option.

@item PATH
Used for locating programs to run.

@item SCREENCAP
For customizing a terminal's @code{TERMCAP} value.

@item SCREENDIR
Alternate socket directory.

@item SCREENRC
Alternate user screenrc file.

@item SHELL
Default shell program for opening windows (default @file{/bin/sh}).

@item STY
Alternate socket name. If @code{screen} is invoked, and the environment variable
@code{STY} is set, then it creates only a window in the running @code{screen}
session rather than starting a new session.

@item SYSSCREENRC
Alternate system screenrc file.

@item TERM
Terminal name.

@item TERMCAP
Terminal description.
@end table

@node Files, Credits, Environment, Top
@chapter Files Referenced
@cindex files

@table @file
@item @code{$SYSSCREENRC}
@itemx /local/etc/screenrc
@code{screen} initialization commands

@item @code{$ISCREENRC}
@itemx @code{$SCREENRC}
@itemx @code{$HOME}/.iscreenrc
@itemx @code{$HOME}/.screenrc
Read in after /local/etc/screenrc

@item @code{$ISCREENDIR}/S-@var{login}
@itemx @code{$SCREENDIR}/S-@var{login}

@item /local/screens/S-@var{login}
Socket directories (default)

@item /usr/tmp/screens/S-@var{login}
Alternate socket directories.

@item @var{socket directory}/.termcap
Written by the @code{dumptermcap} command

@item /usr/tmp/screens/screen-exchange or
@itemx /tmp/screen-exchange
@code{screen} interprocess communication buffer

@item hardcopy.[0-9]
Screen images created by the hardcopy command

@item screenlog.[0-9]
Output log files created by the log command

@item /usr/lib/terminfo/?/* or
@itemx /etc/termcap
Terminal capability databases

@item /etc/utmp
Login records

@item @code{$LOCKPRG}
Program for locking the terminal.
@end table

@node Credits, Bugs, Files, Top
@chapter Credits

@noindent
Authors @*
=======

Originally created by Oliver Laumann, this latest version was
produced by Wayne Davison, Juergen Weigert and Michael Schroeder.

@noindent
Contributors @*
============

@example
     Ken Beal (kbeal@@amber.ssd.csd.harris.com),
     Rudolf Koenig (rfkoenig@@informatik.uni-erlangen.de),
     Toerless Eckert (eckert@@informatik.uni-erlangen.de),
     Wayne Davison (davison@@borland.com),
     Patrick Wolfe (pat@@kai.com, kailand!pat),
     Bart Schaefer (schaefer@@cse.ogi.edu),
     Nathan Glasser (nathan@@brokaw.lcs.mit.edu),
     Larry W. Virden (lvirden@@cas.org),
     Howard Chu (hyc@@hanauma.jpl.nasa.gov),
     Tim MacKenzie (tym@@dibbler.cs.monash.edu.au),
     Markku Jarvinen (mta@@@{cc,cs,ee@}.tut.fi),
     Marc Boucher (marc@@CAM.ORG),
     Doug Siebert (dsiebert@@isca.uiowa.edu),
     Ken Stillson (stillson@@tsfsrv.mitre.org),
     Ian Frechett (frechett@@spot.Colorado.EDU),
     Brian Koehmstedt (bpk@@gnu.ai.mit.edu),
     Don Smith (djs6015@@ultb.isc.rit.edu),
     Frank van der Linden (vdlinden@@fwi.uva.nl),
     Martin Schweikert (schweik@@cpp.ob.open.de),
     David Vrona (dave@@sashimi.lcu.com),
     E. Tye McQueen (tye%spillman.UUCP@@uunet.uu.net),
     Matthew Green (phone@@coombs.anu.edu.au),
     Christopher Williams (cgw@@unt.edu),
     Matt Mosley (mattm@@access.digex.net),
     Gregory Neil Shapiro (gshapiro@@wpi.WPI.EDU),
     Jason Merrill (jason@@jarthur.Claremont.EDU).
@end example

@noindent
Version @*
=======

This is version @value{version}. Its roots are a merge of a custom
version 2.3PR7 by Wayne Davison and several enhancements to Oliver
Laumann's version 2.0. Note that all versions numbered 2.x are copyright
by Oliver Laumann.

@node Bugs, Installation, Credits, Top
@chapter Bugs
@cindex bugs

Just like any other significant piece of software, @code{screen} has a
few bugs and missing features.  Please send in a bug report if you have
found a bug not mentioned here.

@menu
* Known Bugs::                  Problems we know about.
* Reporting Bugs::              How to contact the maintainers.
@end menu

@node Known Bugs, Reporting Bugs,  , Bugs
@section Known Bugs

@itemize @bullet
@item
@samp{dm} (delete mode) and @samp{xs} are not handled correctly (they
are ignored).  @samp{xn} is treated as a magic-margin indicator.

@item
The @samp{GR} set of ISO 2022 is not supported.

@item
There is no keyboard input translation to VT100 sequences.

@item
It is not possible to change the environment variable @code{$TERMCAP}
when reattaching under a different terminal type.

@item
The support of terminfo based systems is very limited. Adding extra
capabilities to @code{$TERMCAP} may not have any effects.

@item
@code{screen} does not make use of hardware tabs.

@item
@code{screen} must be installed setuid root in order to be able to
correctly change the owner of the tty device file for each window.
Special permission may also be required to write the file
@file{/etc/utmp}.

@item
Entries in @file{/etc/utmp} are not removed when @code{screen} is killed
with SIGKILL.  This will cause some programs (like "w" or "rwho") to
advertise that a user is logged on who really isn't.

@item
@code{screen} may give a strange warning when your tty has no utmp
entry.
@end itemize

@node Reporting Bugs,  , Known Bugs, Bugs
@section Reporting Bugs
@cindex bug report

If you find a bug in @code{Screen}, please send electronic mail to
@w{@samp{screen@@uni-erlangen.de}}, and also to
@w{@samp{bug-gnu-utils@@prep.ai.mit.edu}}.  Include the version number
of @code{Screen} which you are using.  Also include in your message the
hardware and operating system, the compiler used to compile, a
description of the bug behavior, and the conditions that triggered the
bug. Please recompile @code{screen} with the @samp{-DDEBUG -DTMPTEST} options
enabled, reproduce the bug, and have a look at the debug output written to
the directory @file{/tmp/debug}. If necessary quote suspect passages from the
debug output and show the contents of your @file{config.h} if it matters.

@node Installation, Concept Index, Bugs, Top
@chapter Installation
@cindex installation

Since @code{screen} uses pseudo-ttys, the select system call, and
UNIX-domain sockets, it will not run under a system that does not
include these features of 4.2 and 4.3 BSD UNIX.

@menu
* Socket Directory::		Where screen stores its handle.
* Compiling Screen::
@end menu

@node Socket Directory,
@section Socket Directory
@cindex socket directory

The socket directory defaults either to @file{$HOME/.screen} or simply to 
@file{/tmp/screens} or preferably to @file{/usr/local/screens} chosen at 
compile-time. If @code{screen} is installed
setuid root, then the administrator should compile screen with an
adequate (not NFS mounted) @code{SOCKDIR}. If @code{screen} is not
running setuid-root, the user can specify any mode 777 directory in the
environment variable @code{$SCREENDIR}.

@node Compiling Screen,  , Socket Directory, Installation
@section Compiling Screen
@cindex compiling screen

To compile and install screen:

The @code{screen} package comes with a @code{GNU Autoconf} configuration 
script. Before you compile the package run 

@center @code{sh ./configure}

This will create a @file{config.h} and @file{Makefile} for your machine.
If @code{configure} fails for some reason, then look at the examples and
comments found in the @file{Makefile.in} and @file{config.h.in} templates.
Rename @file{config.status} to @file{config.status.@var{machine}} when
you want to keep configuration data for multiple architectures. Runing
@code{sh ./config.status.@var{machine}} recreates your configuration 
significantly faster than rerunning @code{configure}. 
@*
Read through the "User Configuration" section of @file{config.h}, and verify
that it suits your needs.
A comment near the top of this section explains why it's best to
install screen setuid to root.
Check for the place for the global @file{screenrc}-file and for the socket
directory.
@*
Check the compiler used in @file{Makefile}, the prefix path where to install
@code{screen}. Then run

@center @code{make}

If @code{make} fails to produce one of the files @file{term.h}, @file{comm.h}
or @file{tty.c}, then use @code{@var{filename.x}.dist} instead.
For additional information about installation of @code{screen} refer to the
file @file{INSTALLATION}, coming with this package.

@node Concept Index, Command Index, Installation, Top
@unnumbered Concept Index

@printindex cp

@node Command Index, Keystroke Index, Concept Index, Top
@unnumbered Command Index

This is a list of all the commands supported by @code{screen}.

@printindex fn

@node Keystroke Index,  , Command Index, Top
@unnumbered Keystroke Index

This is a list of the default key bindings.

The escape character has been omitted from the key sequences, since it
is the same for all bindings.

@printindex ky

@shortcontents
@contents
@bye