This file documents the the 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.

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Screen
******

This file documents the Screen virtual terminal manager, version 3.5.

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 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, 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, 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 C-a from now on), and is followed by one other keystroke.  The command character (see Command Character) and all the key bindings (see 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 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 .screenrc file or at the C-a : command line) and then using it just like the C-a c command.  In addition, new windows can be created by running a command like:

     screen emacs prog.c

from a shell prompt within a previously created window.  This will not run another copy of 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 emacs editor (editing prog.c) and switch to its window.

If /etc/utmp is writable by 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 talk, script, shutdown, rsend, sccs and other similar programs that use the utmp file to determine who you are. As long as screen is active on your terminal, the terminal's own record is removed from the utmp file.  See Login.

Getting Started
***************

Before you begin to use 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 tset, qterm, or just 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: C-a ? (see Key Binding).  Typing these two characters will display a list of the available screen commands and their bindings. Each keystroke is discussed in the section on keystrokes (see Default Key Bindings). Another section (see Customization) deals with the contents of your .screenrc.

If possible, choose a version of your terminal's termcap that has automatic margins turned 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, 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 am), you will want to let screen know about this, since a normal termcap doesn't distinguish this type of automatic margins from a ``true'' am terminal.  You do this by specifying the xn capability in your termcap (see termcap command), or by using the -L command-line option.  screen needs this information to correctly update the screen.  You don't need to worry about this if your terminal type starts with vt, as screen assumes xn in that case.

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

See Special Capabilities, for more information about telling screen what kind of terminal you have.

Invoking Screen
***************

Screen has the following command-line options:

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

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

-c FILE
     Use FILE as the user's configuration file instead of the default of $HOME/.screenrc.

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

-e XY
     Set the command character to X, and the character generating a literal command character (when typed after the command character) to Y.  The defaults are C-a and a, which can be specified as -e^Aa.  This option is equivalent to the escape command (see Command Character).

-f
-fn
-fa
     Set flow-control to on, off, or automatic switching mode, respectively. This option is equivalent to the defflow command (see Flow Control).

-h NUM
     Set the history scrollback buffer to be NUM lines high. Equivalent to the defscrollback command (see Copy).

-i
     Cause the interrupt key (usually C-c) to interrupt the display immediately when flow control is on.  This option is equivalent to the interrupt argument to the defflow command (see Flow Control). Its use is discouraged.

-l
-ln
     Turn login mode on or off (for /etc/utmp updating).  This option is equivalent to the deflogin command (see Login).

-ls
-list
     Do not start screen, but instead print a list of session identification strings (usually of the form PID.TTY.HOST; see Session Name).  Sessions marked detached can be resumed with screen -r.  Those marked attached are running and have a controlling terminal.  Sessions marked as dead should be thoroughly checked and removed.  Ask your system administrator if you are not sure why they died. Remove sessions with the -wipe option.

-L
     Tell 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 .screenrc by specifying xn in a termcap command (see Termcap).

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

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

-r [PID.SESSIONNAME]
     Resume a detached screen session.  No other options (except -d or -D) may be specified, though the session name (see Session Name) may be needed to distinguish between multiple detached screen sessions.

-R
     Resume the first appropriate detached 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 -R had not been specified.  This option is set by default if screen is run as a login-shell.

-s PROGRAM
     Set the default shell to be PROGRAM.  By default, screen uses the value of the environment variable $SHELL, or /bin/sh if it is not defined.  This option is equivalent to the shell command (see Shell).

-S SESSIONNAME
     Set the name of the new session to SESSIONNAME.  This option can be used to specify a meaningful name for the session in place of the default TTY.HOST suffix.  This name identifies the session for the screen -list and screen -r commands.  This option is equivalent to the sessionname command (see Session Name).

-t NAME
     Set the title (name) for the default shell or specified program. This option is equivalent to the shelltitle command (see Shell).

-v
     Print the version number.

-wipe
     List available screens like screen -ls, but remove destroyed sessions instead of marking them as dead.

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

Customizing Screen
******************

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

The .screenrc file
==================

When screen is invoked, it executes initialization commands from the files .screenrc in the user's home directory and /usr/local/etc/screenrc.  These defaults can be overridden in the following ways: For the global screenrc file screen searches for the environment variable $SYSSCREENRC (this override feature may be disabled at compile-time).  The user specific screenrc file is searched for in $ISCREENRC, then $SCREENRC, then $HOME/.iscreenrc and finally defaults to $HOME/.screenrc.  The command line option -c specifies which file to use (see 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 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 # 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 $VAR or ${VAR}.  Note that this causes incompatibility with previous screen versions, as now the '$'-character has to be protected with '\' if no variable substitution is intended. A string in single-quotes is also protected from variable substitution.

Colon
=====

Customization can also be done online, with this command:

 -- Command: colon
     (C-a :)

     Allows you to enter .screenrc command lines.  Useful for on-the-fly modification of key bindings, specific window creation and changing settings.  Note that the set keyword no longer exists, as of version 3.3.  Change default settings with commands starting with def.  You might think of this as the ex command mode of screen, with copy as its vi command mode (see Copy and Paste).

Commands
********

A command in screen can either be bound to a key, invoked from a screenrc file, or called from the colon prompt (see 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:

-- Command: command [-n] ARG1 [ARG2] ...
     (KEYBINDINGS)

     This command does something, but I can't remember what.

An argument in square brackets ([]) is optional.  Many commands take an argument of on or off, which is indicated as STATE in the definition.

Default Key Bindings
====================

As mentioned previously, each keyboard command consists of a 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 C-a a; see below).  Thus, both C-a c and C-a C-c can be used to create a window.

The following table shows the default key bindings:

C-a '
C-a "
     (select)

     Prompt for a window identifier and switch. See Selecting.

C-a 0...9
     (select 0...select 9)

     Switch to window number 0...9.  See Selecting.

C-a C-a
     (other)

     Toggle to the window displayed previously.  See Selecting.

C-a a
     (meta)

     Send the command character (C-a) to window. See escape command. See Command Character.

C-a A
     (title)

     Allow the user to enter a title for the current window. See Naming Windows.

C-a c
C-a C-c
     (screen)

     Create a new window with a shell and switch to that window. See Screen Command.

C-a C
     (clear)

     Clear the screen.  See Clear.

C-a d
C-a C-d
     (detach)

     Detach screen from this terminal.  See Detach.

C-a D D
     (pow_detach)

     Detach and logout.  See Power Detach.

C-a f
C-a C-f
     (flow)

     Cycle flow among on, off or auto.  See Flow.

C-a C-g
     (vbell)

     Toggle visual bell mode.  See Bell.

C-a h
     (hardcopy)

     Write a hardcopy of the current window to the file ``hardcopy.N''. See Hardcopy.

C-a H
     (log)

     Toggle logging of the current window to the file ``screenlog.N''. See Log.

C-a i
C-a C-i
     (info)

     Show info about the current window.  See Info.

C-a k
C-a C-k
     (kill)

     Destroy the current window.  See Kill.

C-a l
C-a C-l
     (redisplay)

     Fully refresh the current window.  See Redisplay.

C-a L
     (login)

     Toggle the current window's login state.  See Login.

C-a m
C-a C-m
     (lastmsg)

     Repeat the last message displayed in the message line. See Last Message.

C-a M
     (monitor) Toggle monitoring of the current window.  See Monitor.

C-a SPC
C-a n
C-a C-n
     (next)

     Switch to the next window.  See Selecting.

C-a N
     (number)

     Show the number (and title) of the current window.  See Number.

C-a p
C-a C-p
C-a C-h
C-a BackSpace
     (prev)

     Switch to the previous window (opposite of C-a n). See Selecting.

C-a q
C-a C-q
     (xon)

     Send a ^Q (ASCII XON) to the current window.  See XON/XOFF.

C-a r
C-a C-r
     (wrap)

     Toggle the current window's line-wrap setting (turn the current window's automatic margins on or off).  See Wrap.

C-a s
C-a C-s
     (xoff)

     Send a ^S (ASCII XOFF) to the current window.  See XON/XOFF.

C-a t
C-a C-t
     (time)

     Show the load average and xref.  See Time.

C-a v
C-a C-v
     (version)

     Display the version and compilation date.  See Version.

C-a w
C-a C-w
     (windows)

     Show a list of active windows.  See Windows.

C-a W
     (width)

     Toggle between 80 and 132 columns.  See Width.

C-a x
C-a C-x
     (lockscreen)

     Lock your terminal.  See Lock.

C-a z
C-a C-z
     (suspend)

     Suspend screen.  See Suspend.

C-a Z
     (reset)

     Reset the virtual terminal to its ``power-on'' values. See Reset.

C-a .
     (dumptermcap)

     Write out a .termcap file.  See Dump Termcap.

C-a ?
     (help)

     Show key bindings.  See Help.

C-a C-\
     (quit)

     Kill all windows and terminate screen.  See Quit.

C-a :
     (colon)

     Enter a command line.  See Colon.

C-a [
C-a C-[
C-a ESC
     (copy)

     Enter copy/scrollback mode.  See Copy.

C-a ]
C-a C-]
     (paste)

     Write the contents of the paste buffer to the stdin queue of the current window.  See Paste.

C-a {
     (history)

     Copy and paste a previous (command) line.  See History.

C-a >
     (writebuf)

     Write the pastebuffer out to the screen-exchange file. See Screen-Exchange.

C-a <
     (readbuf)

     Read the screen-exchange file into the pastebuffer. See Screen-Exchange.

C-a =
     (removebuf)

     Delete the screen-exchange file.  See Screen-Exchange.

C-a _
     (silence)

     Start/stop monitoring the current window for inactivity. See Silence,

Command Summary
===============

acladd USERNAME
     Allow other user in this session.  See Multiuser.

aclchg USERNAME PERMBITS LIST
     Change a user's permissions.  See Multiuser.

acldel USERNAME
     Disallow other user in this session.  See Multiuser.

activity MESSAGE
     Set the activity notification message.  See Monitor.

allpartial STATE
     Set all windows to partial refresh.  See Redisplay.

at [IDENT][#|*|%] COMMAND [ARGS]
     Execute a command at other displays or windows.  See At.

autodetach STATE
     Automatically detach the session on SIGHUP.  See Detach.

autonuke STATE
     Enable a clear screen to discard unwritten output.  See Autonuke.

bell MESSAGE
     Set the bell notification message.  See Bell.

bind KEY [COMMAND [ARGS]]
     Bind a command to a key.  See Bind.

break [DURATION]
     Send a break signal to the current window.  See Break.

bufferfile [EXCHANGE-FILE]
     Select a file for screen-exchange.  See Screen-Exchange.

chdir [DIRECTORY]
     Change the current directory for future windows.  See Chdir.

clear
     Clear the window screen.  See Clear.

colon
     Enter a screen command.  See Colon.

console [STATE]
     Grab or ungrab console output.  See Console.

copy
     Enter copy mode.  See Copy.

copy_reg [KEY]
     Store the copy buffer to a register.  See Registers.

crlf STATE
     Select line break behavior for copying.  See Line Termination.

debug STATE
     Suppress/allow debugging output.  See Debug.

defautonuke STATE
     Select default autonuke behavior.  See Autonuke.

defflow FSTATE
     Select default flow control behavior.  See Flow.

deflogin STATE
     Select default utmp logging behavior.  See Login.

defmode MODE
     Select default file mode for ptys.  See Mode.

defmonitor STATE
     Select default activity monitoring behavior.  See Monitor.

defobuflimit LIMIT
     Select default output buffer limit.  See Obuflimit.

defscrollback NUM
     Set default lines of scrollback.  See Scrollback.

defwrap STATE
     Set default line-wrapping behavior.  See Wrap.

detach
     Disconnect screen from the terminal.  See Detach.

dumptermcap
     Write the window's termcap entry to a file.  See Dump Termcap.

echo [-n] MESSAGE
     Display a message on startup.  See Startup.

escape XY
     Set the command and meta characters.  See Command Character.

exec [[FDPAT] COMMAND [ARGS ...]]
     Run a subprocess (filter).  See Exec.

flow [FSTATE]
     Set flow control behavior.  See Flow.

hardcopy
     Write out the contents of the current window.  See Hardcopy.

hardcopy_append STATE
     Append to hardcopy files.  See Hardcopy.

hardcopydir DIRECTORY
     Place, where to dump hardcopy files.  See Hardcopy.

hardstatus [STATE]
     Use the hardware status line.  See Hardware Status Line.

height [LINES]
     Set display height.  See Height.

help
     Display current key bindings.  See Help.

history
     Find previous command beginning ....  See History.

info
     Display terminal settings.  See Info.

ins_reg [KEY]
     Paste the contents of a register.  See Registers.

kill
     Destroy the current window.  See Kill.

lastmsg
     Redisplay the last message.  See Last Message.

license
     Display licensing information.  See Startup.

lockscreen
     Lock the controlling terminal.  See Lock.

log [STATE]
     Log all output in the current window.  See Log.

logdir DIRECTORY
     Place where to collect logfiles.  See Log.

login [STATE]
     Log the window in /etc/utmp.  See Login.

markkeys STRING
     Rebind keys in copy mode.  See Copy Mode Keys.

meta
     Insert the command character.  See Command Character.

monitor [STATE]
     Monitor activity in window.  See Monitor.

msgminwait SEC
     Set minimum message wait.  See Message Wait.

msgwait SEC
     Set default message wait.  See Message Wait.

multiuser STATE
     Go into single or multi user mode. See Multiuser.

nethack STATE
     Use nethack-like error messages.  See Nethack.

next
     Switch to the next window.  See Selecting.

number [N]
     Change/display the current window's number.  See Number.

obuflimit [LIMIT]
     Select output buffer limit.  See Obuflimit.

other
     Switch to the window you were in last.  See Selecting.

partial STATE
     Set window to partial refresh.  See Redisplay.

password [CRYPTED_PW]
     Set reattach password.  See Detach.

paste
     Paste contents of copy buffer.  See Paste.

pow_break
     Close and Reopen the window's terminal.  See Break.

pow_detach
     Detach and hang up.  See Power Detach.

pow_detach_msg MESSAGE
     Set message displayed on pow_detach.  See Power Detach.

prev
     Switch to the previous window.  See Selecting.

process [KEY]
     Treat a register as input to screen.  See Registers.

quit
     Kill all windows and exit.  See Quit.

readbuf
     Read the copy buffer from the screen-exchange file.  See Screen-Exchange.

redisplay
     Redisplay the current window.  See Redisplay.

register KEY STRING
     Store a string to a register.  See Registers.

removebuf
     Delete the screen-exchange file.  See Screen-Exchange.

reset
     Reset the terminal settings for the window.  See Reset.

screen [OPTS] [N] [CMD [ARGS]]
     Create a new window.  See Screen Command.

scrollback NUM
     Set size of scrollback buffer.  See Scrollback.

select [N]
     Switch to a specified window.  See Selecting.

sessionname [NAME]
     Name this session.  See Session Name.

setenv [VAR [STRING]]
     Set an environment variable for new windows.  See Setenv.

shell COMMAND
     Set the default program for new windows.  See Shell.

shelltitle TITLE
     Set the default name for new windows.  See Shell.

silence [STATE|SECONDS]
     Monitor window for inactivity.  See Silence.

silencewait SECONDS
     Default timeout to trigger an inactivity notify.  See Silence.

sleep NUM
     Pause during startup.  See Startup.

slowpaste MSEC
     Slow down pasting.  See Paste.

startup_message STATE
     Display copyright notice on startup.  See Startup.

suspend
     Put session in background.  See Suspend.

term TERM
     Set $TERM for new windows.  See Term.

termcap TERM TERMINAL-TWEAKS [WINDOW-TWEAKS]
     Tweak termcap entries for best performance.  See Termcap Syntax.

terminfo TERM TERMINAL-TWEAKS [WINDOW-TWEAKS]
     Ditto, for terminfo systems.  See Termcap Syntax.

time
     Display time and load average.  See Time.

title [WINDOWTITLE]
     Set the name of the current window.  See Title Command.

unsetenv VAR
     Unset environment variable for new windows.  See Setenv.

vbell [STATE]
     Use visual bell.  See Bell.

vbell_msg MESSAGE
     Set vbell message.  See Bell.

vbellwait SEC
     Set delay for vbell message.  See Bell.

version
     Display screen version.  See Version.

wall MESSAGE ...
     Write a message to all displays.  See Multiuser.

width [NUM]
     Set the width of the window.  See Width.

windows
     List active windows.  See Windows.

wrap [STATE]
     Control line-wrap behavior.  See Wrap.

writebuf
     Write copy buffer to screen-exchange file.  See Screen-Exchange.

writelock ON|OFF|AUTO
     Grant exclusive write permission.  See Multiuser.

xoff
     Send an XOFF character.  See XON/XOFF.

xon
     Send an XON character.  See XON/XOFF.

zombie [KEY]
     Keep dead windows.  See Zombie.

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...9 is assigned to it.  There can be no more than 10 windows active at any one time.

Chdir
=====

 -- Command: chdir [directory]
     (none)

     Change the current directory of screen to the specified directory or, if called without an argument, to your home directory (the value of the environment variable $HOME).  All windows that are created by means of the screen command from within .screenrc or by means of C-a : screen ... or C-a c use this as their default directory.  Without a chdir command, this would be the directory from which screen was invoked.  Hardcopy and log files are always written to the window's default directory, not the current directory of the process running in the window.  You can use this command multiple times in your .screenrc to start various windows in different default directories, but the last chdir value will affect all the windows you create interactively.

Screen Command
==============

 -- Command: screen [opts] [n] [cmd [args]]
     (C-a c, C-a C-c)

     Establish a new window.  The flow-control options (-f, -fn and -fa), title option (-t), login options (-l and -ln) , terminal type option (-T TERM) and scrollback option (-h NUM) may be specified for each command.  If an optional number N in the range 0...9 is given, the window number 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 screen, this command (with the given arguments) is started in the window; otherwise, a shell is created.

Thus, if your .screenrc contains the lines

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

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 foobar in window #2).  If you do not include any screen commands in your .screenrc file, then screen defaults to creating a single shell window, number zero.  When the initialization is completed, screen switches to the last window specified in your .screenrc file or, if none, it opens default window #0.

Setenv
======

 -- Command: setenv var string
     (none)

     Set the environment variable VAR to value STRING. If only 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.

 -- Command: unsetenv var
     (none)

     Unset an environment variable.

Shell
=====

 -- Command: shell command
     (none)

     Set the command to be used to create a new shell.  This overrides the value of the environment variable $SHELL.  This is useful if you'd like to run a tty-enhancer which is expecting to execute the program specified in $SHELL.  If the command begins with a - character, the shell will be started as a login-shell.

 -- Command: shelltitle title
     (none)

     Set the title for all shells created during startup or by the C-a C-c command.  See Naming Windows, for details about what titles are.

Term
====

 -- Command: term term
     (none)

     In each window screen opens, it sets the $TERM variable to screen by default, unless no description for screen is installed in the local termcap or terminfo data base. In that case it pretends that the terminal emulator is vt100. This won't do much harm, as screen is VT100/ANSI compatible.  The use of the term command is discouraged for non-default purpose. That is, one may want to specify special $TERM settings (e.g. vt100) for the next screen rlogin othermachine command. Use the command screen -T vt100 rlogin othermachine rather than setting (term vt100) and resetting (term screen) the default before and after the screen command.

Selecting a Window
******************

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

Moving Back and Forth
=====================

 -- Command: next
     (C-a SPC, C-a n, 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-SPC generates a NUL character, so you must release the control key before pressing space.)

 -- Command: prev
     (C-a p, C-a C-p)

     Switch to the previous window (the opposite of C-a n).

Other Window
============

 -- Command: other
     (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 -e]x, this command becomes ]], not ]C-a (see Command Character).  On the other hand, if you use the option -e``, this command remains ` C-a, since `` is bound to meta.

Select
======

 -- Command: select [n]
     (C-a N, C-a ', C-a ")

     Switch to the window with the number N. If no window number is specified, you get prompted for an identifier. This can be a window name (title) or a number.

Session Management Commands
***************************

Perhaps the most useful feature of 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.

Detach
======

 -- Command: autodetach state
     (none)

     Sets whether screen will automatically detach upon hangup, which saves all your running programs until they are resumed with a screen -r command.  When turned off, a hangup signal will terminate screen and all the processes it contains. Autodetach is on by default.

 -- Command: detach
     (C-a d, C-a C-d)

     Detach the screen session (disconnect it from the terminal and put it into the background).  A detached screen can be resumed by invoking screen with the -r option. (see Invoking Screen)

 -- Command: password [crypted_pw]
     (none)

     Present a crypted password in your .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 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.

Power Detach
============

 -- Command: pow_detach
     (C-a D)

     Mainly the same as detach, but also sends a HANGUP signal to the parent process of screen.

     Caution: This will result in a logout if screen was started from your login shell.

 -- Command: pow_detach_msg message
     (none)

     The 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.

Lock
====

 -- Command: lockscreen
     (C-a x, C-a C-x)

     Call a screenlock program (/local/bin/lck or /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 $LOCKPRG (which must be set in the shell from which screen is started) and is executed with the user's uid and gid.

Multiuser Session
=================

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

Multiuser
---------

 -- Command: multiuser STATE
     (none)

     Switch between single-user and multi-user mode. Standard screen operation is single-user. In multi-user mode the commands acladd and acldel can be used to enable (and disable) other users accessing this screen.

Acladd
------

 -- Command: acladd USERNAME
     (none)

     Enable a user to (fully) access this screen session. Necessary to allow other users to attach to this screen session. Same as aclchg USERNAME +rwx "#?". Multi-user mode only.

Aclchg
------

 -- Command: aclchg USERNAME PERMBITS LIST
     (none)

     Change a users permissions. Permission bits are represented as r, w and x. Prefixing + grants the permission, - removes it. The third parameter is a komma seperated list of commands or windows (specified either by number or title). The special list # refers to all windows, ? to all commands. A Command can be executed when the user has the x bit for it. the user can type input to a window, when he has its w bit set and no other user obtains a writelock for this window. Other bits are currently ignored. Multi-user mode only.

Acldel
------

 -- Command: acldel 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.

Wall
----

 -- Command: wall MESSAGE ...
     (none)

     Write a message to all displays. The message will appear in the terminals status line.

Writelock
---------

 -- Command: writelock 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 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 writelock off. If the user issues the command writelock on he keeps the exclusive write permission while switching to other windows.

Session Name
============

 -- Command: sessionname [name]
     (none)

     Rename the current session. Note that for screen -list the name shows up with the process-id prepended. If the argument NAME is omitted, the name of this session is displayed.

     Caution: The $STY environment variable still reflects the old name. This may result in confusion.  The default is constructed from the tty and host names.

Suspend
=======

 -- Command: suspend
     (C-a z, C-a C-z)

     Suspend screen.  The windows are in the detached state while screen is suspended.  This feature relies on the parent shell being able to do job control.

Quit
====

 -- Command: quit
     (C-a C-\)

     Kill all windows and terminate screen.  Note that on vt100-style terminals the keys C-4 and C-\ are identical.  So be careful not to type C-a C-4 when selecting window no. 4.  Use the empty bind command (as in bind "^\") to remove a key binding (see Key Binding).

Window Settings
***************

These commands control the way screen treats individual windows in a session.  See Virtual Terminal, for comands to control the terminal emulation itself.

Naming Windows (Titles)
=======================

You can customize each window's name in the window display (viewed with the windows command (see 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 shelltitle command (see Shell).  You can specify the name you want for a window with the -t option to the screen command when the window is created (see Screen Command).  To change the name after the window has been created you can use the title-string escape-sequence (ESC k NAME ESC \) and the 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 title command to set things quickly without prompting.

Title Command
-------------

 -- Command: title [windowtitle]
     (C-a A)

     Set the name of the current window to WINDOWALIAS. If no name is specified, screen prompts for one.

Dynamic Titles
--------------

screen has a shell-specific heuristic that is enabled by setting the window's name to SEARCH|NAME and arranging to have a null title escape-sequence output as a part of your prompt.  The SEARCH portion specifies an end-of-prompt search string, while the NAME portion specifies the default shell name for the window.  If the NAME ends in a : screen will add what it believes to be the current command running in the window to the end of the specified name (e.g. 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 (ESC k ESC \) as a part of your prompt. The last part of your prompt must be the same as the string you specified for the SEARCH portion of the title.  Once this is set up, 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 !, %, or ^, 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.

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:

     set prompt='[0000mk\% '

The escape-sequence [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:

     set prompt="%{\ek\e\\%}\% "

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

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

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

Setting up shell Titles in your .screenrc
-----------------------------------------

Here are some .screenrc examples:

     screen -t top 2 nice top

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

     shelltitle '> |csh'
     screen 1

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:

     /usr/joe/src/dir> trn

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

     bind R screen -t '% |root:' su

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

     % !em
     emacs file.c

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

     bind o title
     bind E title ""
     bind u title (unknown)

The first binding doesn't have any arguments, so it would prompt you for a title when you type 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 (unknown) (C-a u).

Autonuke
========

 -- Command: autonuke STATE
     (none)

     Sets whether a clear screen sequence should nuke all the output that has not been written to the terminal. See Obuflimit.

 -- Command: defautonuke STATE
     (none)

     Same as the autonuke command except that the default setting for new displays is changed. Initial setting is off. Note that you can use the special AN terminal capability if you want to have a terminal type dependant setting.

Console
=======

 -- Command: console [STATE]
     (none)

     Grabs or ungrabs the machines console output to a window. When the argument is ommitted the current state is displayed.

Kill
====

 -- Command: kill
     (C-a k, C-a C-k)

     Kill the current window.

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

Login
=====

 -- Command: deflogin state
     (none)

     Same as the login command except that the default setting for new windows is changed.  This defaults to `on' unless otherwise specified at compile time (see Installation). Both commands are only present when screen has been compiled with utmp support.

 -- Command: login [state]
     (C-a L)

     Adds or removes the entry in /etc/utmp for the current window. This controls whether or not the window is logged in.  In addition to this toggle, it is convenient to have ``log in'' and ``log out'' keys.  For instance, bind I login on and bind O login off will map these keys to be C-a I and C-a O (see Key Binding).

Mode
====

 -- Command: defmode mode
     (none)

     The mode of each newly allocated pseudo-tty is set to MODE. 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 -ln was specified for creation. see Screen Command).

Monitoring
==========

 -- Command: activity message
     (none)

     When any activity occurs in a background window that is being monitored, screen displays a notification in the message line.  The notification message can be redefined by means of the activity command.  Each occurrence of % in MESSAGE is replaced by the number of the window in which activity has occurred, and each occurrence of ~ is replaced by the definition for bell in your termcap (usually an audible bell).  The default message is

          'Activity in window %'

     Note that monitoring is off for all windows by default, but can be altered by use of the monitor command (C-a M).

 -- Command: defmonitor state
     (none)

     Same as the monitor command except that the default setting for new windows is changed.  Initial setting is `off'.

 -- Command: monitor [state]
     (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 @ in the window-status display (see Windows).  Monitoring defaults to off for all windows.

Obuflimit
=========

 -- Command: obuflimit [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 xterm), you can set it to some higher value. If no argument is specified, the current setting is displayed.

 -- Command: defobuflimit LIMIT
     (none)

     Same as the obuflimit command except that the default setting for new displays is changed. Initial setting is 256 bytes. Note that you can use the special OL terminal capability if you want to have a terminal type dependant limit.

Windows
=======

 -- Command: windows
     (C-a w, 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 *; the previous window is marked with a -; all the windows that are logged in are marked with a $ (see Login); a background window that has received a bell is marked with a !; a background window that is being monitored and has had activity occur is marked with an @ (see Monitor); a window which has output logging turned on is marked with (L); windows occupied by other users are marked with &; windows in the zombie state are marked with Z. If this list is too long to fit on the terminals status line only the portion around the current window is displayed.

Virtual Terminal
****************

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

Control Sequences
=================

The following is a list of control sequences recognized by screen.  (V) and (A) indicate VT100-specific and ANSI- or ISO-specific functions, respectively.

     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)     Standout Mode (ANSI: Italicized)
                4                    Underlined
                5                    Blinking
                7                    Negative Image
                22           (A)     Normal Intensity
                23           (A)     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 (On followed by Off)
                ?6           (V)     Origin Mode
                ?7           (V)     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 Ph lines and
                                     Pw columns (SunView special)
     ESC [ c                         Send VT100 Identification String
     ESC [ 6 n                       Send Cursor Position Report

Bell
====

 -- Command: bell message
     (none)

     When a bell character is sent to a background window, screen displays a notification in the message line.  The notification message can be re-defined by means of the bell command.  Each occurrence of % in MESSAGE is replaced by the number of the window to which a bell has been sent, and each occurrence of ~ is replaced by the definition for bell in your termcap (usually an audible bell). The default message is

          'Bell in window %'

     An empty message can be supplied to the bell command to suppress output of a message line (bell "").

 -- Command: vbell [state]
     (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.  See Visual Bell (The Termcap Manual), for more information on visual bells.  The equivalent terminfo capability is flash.

 -- Command: vbell_msg message
     (none)

     Sets the visual bell message. MESSAGE is printed to the status line if the window receives a bell character (^G) and vbell is set to on.  The default message is Wuff, Wuff!!.

 -- Command: vbellwait sec
     (none)

     Define a delay in seconds after each display of screen 's visual bell message. The default is 1 second.

Clear
=====

 -- Command: clear
     (C-a C)

     Clears the screen and saves its contents to the scrollback buffer.

Height
======

 -- Command: height [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.

Info
====

 -- Command: info
     (C-a i, C-a C-i)

     Uses the message line to display some information about the current window: the cursor position in the form (COLUMN,ROW) starting with (1,1), the terminal width and height plus the size of the scrollback buffer in lines, like in (80,24)+50, various flag settings (flow-control, insert mode, origin mode, wrap mode, application-keypad mode, output logging, activity monitoring, and redraw (+ indicates enabled, - not)), the currently active character set (G0, G1, G2, or G3), and in square brackets the terminal character sets that are currently designated as G0 through G3.  For system information use time.

Redisplay
=========

 -- 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 allpartial off.

 -- Command: partial state
     (none)

     Defines whether the display should be refreshed (as with redisplay) after switching to the current window. This command only affects the current window.  To affect all windows use the allpartial command.  Default is off, of course.

 -- Command: redisplay
     (C-a l, C-a C-l)

     Redisplay the current window.  Needed to get a full redisplay in partial redraw mode.

Wrap
====

 -- Command: wrap state
     (C-a r, 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 on.

 -- Command: defwrap state
     (none)

     Same as the wrap command except that the default setting for new windows is changed. Initially line-wrap is on and can be toggled with the wrap command (C-a r) or by means of "C-a : wrap on|off".

Reset
=====

 -- Command: reset
     (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.

Width
=====

 -- Command: width [num]
     (C-a W)

     Toggle the window width between 80 and 132 columns, or set it to NUM columns if an argument is specified.  This requires a capable terminal and the termcap entries Z0 and Z1.  See the termcap command (see Termcap), for more information.

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.

Copying
=======

 -- Command: copy
     (C-a [, C-a C-[, C-a 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 vi-like full screen editor is active, with controls as outlined below.

CR/LF
-----

 -- Command: crlf state
     (none)

     This affects the copying of text regions with the C-a [ command. If it is set to on, lines will be separated by the two character sequence CR/LF.  Otherwise only LF is used. crlf is off by default.

Scrollback
----------

 -- Command: defscrollback num
     (none)

     Same as the scrollback command except that the default setting for new windows is changed.  Defaults to 100.

 -- Command: scrollback num
     (none)

     Set the size of the scrollback buffer for new windows to NUM lines.  The default scrollback is 100 lines.  Use C-a i to view the current setting.

markkeys
--------

 -- Command: markkeys string
     (none)

     This is a method of changing the keymap used for copy/history mode.  The string is made up of OLDCHAR=NEWCHAR pairs which are separated by :. Example: The command markkeys h=^B:l=^F:$=^E would set some keys to be more familiar to emacs users.

Movement Keys
-------------

h, j, k, l move the cursor line by line or column by column.

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

H, M and L move the cursor to the leftmost column of the top, center or bottom line of the window.

+ and - move the cursor to the leftmost column of the next or previous line.

G moves to the specified absolute line (default: end of buffer).

| moves to the specified absolute column.

w, b, e move the cursor word by word.

C-u and C-d scroll the display up/down by the specified amount of lines while preserving the cursor position. (Default: half screenfull).

C-b and C-f move the cursor up/down a full screen.

g moves to the beginning of the buffer.

% jumps to the specified percentage of the buffer.

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

Marking
-------

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

Y and y can be used to mark one whole line or to mark from start of line.

W marks exactly one word.

Repeat Count
------------

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

Searching
---------

/ vi-like search forward.

? vi-like search backward.

C-a s emacs style incremental search forward.

C-r emacs style reverse i-search.

Specials
--------

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

c or 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: C-a [ M 20 l SPACE c 10 l 5 j C SPACE.

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:

C-a [ M 20 l SPACE 10 l 5 j SPACE

and notice the difference in the amount of text copied.

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 set crlf on.

v is for all the vi users who use :set numbers - it toggles the left margin between column 9 and 1.

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

A turns on append mode and sets a (second) mark.

> sets the (second) mark and writes the contents of the copybuffer to the screen-exchange file (/tmp/screen-exchange per default) once copy-mode is finished.  See Screen-Exchange.

This example demonstrates how to dump the whole scrollback buffer to that file:
C-a [ g SPACE G $ >.

C-g gives information about the current line and column.

@ does nothing.  Absolutely nothing.  Does not even exit copy mode.

Paste
=====

 -- Command: paste [registers]
     (C-a ], C-a C-])

     Write the contents of the specified registers to the stdin stream of the current window.  The register . 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 copy, history and readbuf commands.

 -- Command: slowpaste msec
     (none)

     Define the speed text is inserted by the paste command. If the slowpaste value is nonzero text is written character by character. screen will pause for MSEC milliseconds after each write to allow the application to process the input. only use slowpaste if your underlying system exposes flow control problems while pasting large amounts of text.

Registers
=========

 -- Command: copy_reg [key]
     (none)

     Store the current copybuffer contents in a register referenced by KEY. If the name is omitted you will be prompted to press the key.

 -- Command: ins_reg [key]
     (none)

     Paste contents of register KEY into the current window's input stream.

 -- Command: process [key]
     (none)

     Stuff the contents of the specified register into the 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.

 -- Command: register key string
     (none)

     Save the specified STRING to the register KEY.

Screen-Exchange
===============

 -- Command: bufferfile [exchange-file]
     (none)

     Change the filename used for reading and writing with the copybuffer. If the EXCHANGE-FILE parameter is omitted, screen reverts to the default of /tmp/screen-exchange.  The following example will paste the system's password file into the screen window:

          C-a : bufferfile /etc/passwd
          C-a < C-a ]

 -- Command: readbuf
     (C-a <)

     Reads the contents of the current screen-exchange file into the copy buffer.

 -- Command: removebuf
     (C-a =)

     Unlinks the screen-exchange file.

 -- Command: writebuf
     (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 screen users on the same host. See also C-a ESC (see Copy).

History
=======

 -- Command: history
     (C-a {)

     Usually users work with a shell that allows easy access to previous commands.  For example, csh has the command !! to repeat the last command executed.  screen provides a primitive way of recalling ``the command that started ...'': You just type the first letter of that command, then hit C-a { and 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).

Subprocess Execution
********************

Control Input or Output of a window by another filter process. Use with care!

Exec
====

 -- Command: exec [[FDPAT] NEWCOMMAND [ARGS ... ]]
     (none)

     Run a unix subprocess (specified by an executable path 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 FDPAT. This pattern is basically a three character sequence representing stdin, stdout and stderr of newcommand. A dot (.) connects the file descriptor to screen. An exclamation mark (!) causes the file descriptor to be connected to the already running process. A colon (:) combines both. User input will go to newcommand unless newcommand requests the old process' output (FDPATs first character is ! or :) or a pipe symbol (|) is added to the end of FDPAT. Invoking exec without arguments shows name and arguments of the currently running subprocess in this window. When a subprocess is running the kill command will affect it instead of the windows process. Refer to the postscript 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.

Using Exec
==========

Abbreviations:

  * Whitespace between the word exec and FDPAT and the command name can be omitted.

  * Trailing dots and a FDPAT consisting only of dots can be omitted.

  * A simple | is synonymous for the !..| pattern.

  * The word exec can be ommitted when the | abbreviation is used.

  * The word exec can always be replaced by leading !.

Examples:

!/bin/sh
exec /bin/sh
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 /bin/sh.

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

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

!: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 Error appears in the window.

Key Binding
***********

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

The bind command
================

 -- Command: bind key [command [args]]
     (none)

     Bind a command to a key.  The KEY argument is either a single character, a two-character sequence of the form ^x (meaning 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 \^ or \\.  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 COMMAND argument can be any command (see Command Index).

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

Examples of the bind command
============================

Some examples:

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

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

Command Character
=================

 -- Command: escape xy
     (none)

     Set the command character to X and the character generating a literal command character to Y (just like with the -e option).  Each argument is either a single character, a two-character sequence of the form ^x (meaning 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 \^ or \\.  The default is ^Aa, but `` is recommended by one of the authors.

 -- Command: meta
     (C-a a)

     Send the command character (C-a) to the process in the current window.  The keystroke for this command is the second parameter to the -e command line switch (see Invoking Screen), or the escape .screenrc directive.

Help
====

 -- Command: help
     (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. See Default Key Bindings.

Flow Control
************

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. emacs).

About 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 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 C-a q (xon) and 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 -f option or the 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 flow command bound to C-a f.

The automatic flow-switching mode deals with flow control using the TIOCPKT mode (like 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 interrupt option (add the interrupt flag to the flow command in your .screenrc, or use the -i command-line option).  This causes the output that 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 C-a l you would see the version of the output you would have gotten without 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 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 C-a l will restore it.  Give each mode a try, and use whichever mode you find more comfortable.

Flow
====

 -- Command: defflow fstate [interrupt]
     (none)

     Same as the flow command except that the default setting for new windows is changed. Initial setting is `auto'. Specifying flow auto interrupt has the same effect as the command-line options -fa and -i.

 -- Command: flow [fstate]
     (C-a f, C-a C-f)

     Sets the flow-control mode for this window to FSTATE, which can be on, off or auto. Without parameters it cycles the current window's flow-control setting.  Default is set by `defflow'.

XON and XOFF
============

 -- Command: xon
     (C-a q, C-a C-q)

     Send a ^Q (ASCII XON) to the program in the current window.  Redundant if flow control is set to off or auto.

 -- Command: xoff
     (C-a s, C-a C-s)

     Send a ^S (ASCII XOFF) to the program in the current window.

Termcap
*******

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 screen.

Choosing the termcap entry for a window
=======================================

Usually 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 screen has to tell the applications that some of the features are missing. This is no problem on machines using termcap, because screen can use the $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 screen offers a way to deal with these cases. Here is how it works:

When screen tries to figure out a terminal name for itself, it first looks for an entry named screen.TERM, where TERM is the contents of your $TERM variable.  If no such entry exists, screen tries screen (or screen-w, if the terminal is wide (132 cols or more)).  If even this entry cannot be found, 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 screen (named screen.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 $TERM variable of all new windows. screen also sets the $TERMCAP variable reflecting the capabilities of the virtual terminal emulated. Furthermore, the variable $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, screen does not put the us and ue capabilities into the window's $TERMCAP variable, accordingly.  However, a minimum number of capabilities must be supported by a terminal in order to run screen; namely scrolling, clear screen, and direct cursor addressing (in addition, screen does not run on hardcopy terminals or on terminals that over-strike).

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

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

When the boolean G0 capability is present in the termcap entry for the terminal on which screen has been called, the terminal emulation of 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: lock shift G0 (SI), lock shift G1 (SO), lock shift G2, lock shift G3, single shift G2, and single shift G3.  When a virtual terminal is created or reset, the ASCII character set is designated as G0 through G3.  When the G0 capability is present, screen evaluates the capabilities S0, E0, and C0 if present. S0 is the sequence the terminal uses to enable and start the graphics character set rather than SI.  E0 is the corresponding replacement for SO. C0 gives a character by character translation string that is used during semi-graphics mode. This string is built like the acsc terminfo capability.

When the po and pf capabilities are present in the terminal's termcap entry, applications running in a 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 $TERMCAP variable of the virtual terminal if they can be efficiently implemented by the physical terminal.  For instance, dl (delete line) is only put into the $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 $TERMCAP cannot be modified by parent processes.  You can force screen to include all capabilities in $TERMCAP with the -a command-line option (see Invoking Screen).

Write out the window's termcap entry
====================================

 -- Command: dumptermcap
     (C-a .)

     Write the termcap entry for the virtual terminal optimized for the currently active window to the file .termcap in the user's $HOME/.screen directory (or wherever screen stores its sockets. see Files).  This termcap entry is identical to the value of the environment variable $TERMCAP that is set up by screen for each window. For terminfo based systems you will need to run a converter like captoinfo and then compile the entry with tic.

The termcap command
===================

 -- Command: termcap term terminal-tweaks [window-tweaks]
 -- 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, screen will understand the terminfo command which has the same effects as the termcap command. Thus users can write one .screenrc file that handles both cases, although terminfo syntax is slightly different from termcap syntax.

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

Each TWEAK argument contains one or more termcap defines (separated by :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 (see Virtual Terminal).

Termcap Examples
================

Some examples:

     termcap xterm*  xn:hs@

Informs screen that all terminals that begin with 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 @ to turn entries off).  Note that we assume xn for all terminal names that start with vt, but only if you don't specify a termcap command for that terminal.

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

Specifies the firm-margined xn capability for all terminals that begin with 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.)

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

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

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

Takes a h19 or z19 termcap and turns off auto-margins (am@) and enables the insert mode (im) and end-insert (ei) capabilities (the @ in the im string is after the =, so it is part of the string).  Having the im and 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 $SCREENCAP variable prior to running screen.  See Virtual Terminal, for the details of the screen terminal emulation.  See Termcap (The Termcap Manual), for more information on termcap definitions.

Special Terminal Capabilities
=============================

The following table describes all terminal capabilities that are recognized by screen and are not in the termcap manual (see Termcap (The Termcap Manual)).

LP
     (bool)

     Terminal has vt100 style margins (`magic margins'). Note that this capability is obsolete --- screen now uses xn instead.

Z0
     (str)

     Change width to 132 columns.

Z1
     (str)

     Change width to 80 columns.

WS
     (str)

     Resize display. This capability has the desired width and height as arguments.  SunView(tm) example: \E[8;%d;%dt.

B8
     (str)

     Tell screen to look out for characters with 8th bit set. If such a character is found 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 screen, too. (Example: Single Shift G2 = \EN.)

OP
     (bool)

     Don't do full vt100-style margin emulation. Same as the -O option.

NF
     (bool)

     Terminal doesn't need flow control. Send ^S and ^Q direct to the application. Same as flow off. The opposite of this capability is xo.

G0
     (bool)

     Terminal can deal with ISO2022 font selection sequences.

S0
     (str)

     Switch charset G0 to the specified charset. Default is \E(%d.

E0
     (str)

     Switch charset G0 back to standard charset. Default is \E(B.

C0
     (str)

     Use the string as a conversion table for font 0. See the ac capability for more details.

CS
     (str)

     Switch cursor keys to application mode.

CE
     (str)

     Switch cursor keys to cursor mode.

The Message Line
****************

screen displays informational messages and other diagnostics in a 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.

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 Privacy message control sequence.  For instance, from within the shell, try something like:

     echo "^Hello world from window $WINDOW\"

where is ASCII ESC and ^ is a literal caret or up-arrow.

Hardware Status Line
====================

 -- Command: hardstatus [state]
     (none)

     Toggles the use of the terminal's hardware status line. If on, 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 on whenever the "hs" capability is present.

Display Last Message
====================

 -- Command: lastmsg
     (C-a m, 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.

Message Wait
============

 -- Command: msgminwait sec
     (none)

     Defines the time screen delays a new message when another is currently displayed.  Defaults to 1 second.

 -- Command: msgwait sec
     (none)

     Defines the time a message is displayed, if screen is not disturbed by other activity.  Defaults to 5 seconds.

Logging
*******

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

hardcopy
========

 -- Command: hardcopy
     (C-a h, C-a C-h)

     Writes out the current display contents to the file hardcopy.N in the window's default directory, where N is the number of the current window.  This either appends or overwrites the file if it exists, as determined by the hardcopy_append command.

 -- Command: hardcopy_append state
     (none)

     If set to on, screen will append to the hardcopy.N files created by the command hardcopy; otherwise, these files are overwritten each time.

 -- Comand: hardcopydir directory
     (none)

     Defines a directory where hardcopy files will be placed. If unset hardcopys are dumped in screens current working directory.

log
===

 -- Command: log [state]
     (C-a H)

     Begins/ends logging of the current window to the file screenlog.N in the window's default directory, where 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 off.

 -- Comand: logdir directory
     (none)

     Defines a directory where logfiles will be placed. If unset logfiles are written in screens current working directory.

Startup
*******

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

echo
====

 -- Command: echo [-n] message
     (none)

     The echo command may be used to annoy screen users with a 'message of the day'. Typically installed in a global screenrc. See also sleep.  Echo is also useful for online checking of environment variables.

sleep
=====

 -- Command: sleep num
     (none)

     This command will pause the execution of a .screenrc file for NUM seconds.  Keyboard activity will end the sleep.  It may be used to give users a chance to read the messages output by echo.

Startup Message
===============

 -- Command: startup_message state
     (none)

     Select whether you want to see the copyright notice during startup. Default is on, as you probably noticed.

Miscellaneous commands
**********************

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

At
==

 -- Command: at [identifier][#|*|%] command [args]
     (none)

     Execute a command at other displays or windows as if it had been entered there. 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 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 IDENTIFIER% identifier is matched against displays. Displays are named after the ttys they attach. The prefix /dev/ or /dev/tty may be ommited from the identifier. If IDENTIFIER has a # or nothing appended it is matched against window numbers and titles. Omitting an identifier in front of the #, * or % 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.

Break
=====

 -- Command: break [duration]
     (none)

     Send a break signal for DURATION*0.25 seconds to this window. Most useful if a character device is attached to the window rather than a shell process.

 -- Command: pow_break
     (none)

     Reopen the window's terminal line and send a break condition.

Debug
=====

 -- Command: debug [on|off]
     (none)

     Turns runtime debugging on or off. If screen has been compiled with option -DDEBUG debugging is available and is turned on per default. Note that this command only affects debugging output from the main SCREEN process.

License
=======

 -- Command: license
     (none)

     Display the disclaimer page. This is done whenever screen is started without options, which should be often enough.

Nethack
=======

 -- Command: nethack state
     (none)

     Changes the kind of error messages used by screen.  When you are familiar with the game 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 screen was compiled with the NETHACK flag defined (see Installation). The default setting is then determined by the presence of the environment variable $NETHACKOPTIONS.

Number
======

 -- Command: number [N]
     (C-a N)

     Change the current window's number. If the given number 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.

Silence
=======

 -- Command: silence [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 silencewait command or by specifying a number of seconds instead of on or off. Silence is initially off for all windows.

 -- Command: silencewait SECONDS
     (none)

     Define the time that all windows monitored for silence should wait before displaying a message. Default is 30 seconds.

Time
====

 -- Command: time
     (C-a t, 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 info (see Info).

Version
=======

 -- Command: version
     (C-a v, C-a C-v)

     Display the version and modification date in the message line.

Zombie
======

 -- Command: zombie [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 kill command is issued.

Environment Variables
*********************

COLUMNS
     Number of columns on the terminal (overrides termcap entry).

HOME
     Directory in which to look for .screenrc.

ISCREENRC
     Alternate user screenrc file.

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

LOCKPRG
     Screen lock program.

NETHACKOPTIONS
     Turns on nethack option.

PATH
     Used for locating programs to run.

SCREENCAP
     For customizing a terminal's TERMCAP value.

SCREENDIR
     Alternate socket directory.

SCREENRC
     Alternate user screenrc file.

SHELL
     Default shell program for opening windows (default /bin/sh).

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

SYSSCREENRC
     Alternate system screenrc file.

TERM
     Terminal name.

TERMCAP
     Terminal description.

Files Referenced
****************

$SYSSCREENRC
/local/etc/screenrc
     screen initialization commands

$ISCREENRC
$SCREENRC
$HOME/.iscreenrc
$HOME/.screenrc
     Read in after /local/etc/screenrc

$ISCREENDIR/S-LOGIN
$SCREENDIR/S-LOGIN

/local/screens/S-LOGIN
     Socket directories (default)

/usr/tmp/screens/S-LOGIN
     Alternate socket directories.

SOCKET DIRECTORY/.termcap
     Written by the dumptermcap command

/usr/tmp/screens/screen-exchange or
/tmp/screen-exchange
     screen interprocess communication buffer

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

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

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

/etc/utmp
     Login records

$LOCKPRG
     Program for locking the terminal.

Credits
*******

Authors

=======

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

Contributors

============

          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).

Version

=======

This is version 3.5. 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.

Bugs
****

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

Known Bugs
==========

  * dm (delete mode) and xs are not handled correctly (they are ignored).  xn is treated as a magic-margin indicator.

  * The GR set of ISO 2022 is not supported.

  * There is no keyboard input translation to VT100 sequences.

  * It is not possible to change the environment variable $TERMCAP when reattaching under a different terminal type.

  * The support of terminfo based systems is very limited. Adding extra capabilities to $TERMCAP may not have any effects.

  * screen does not make use of hardware tabs.

  * 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 /etc/utmp.

  * Entries in /etc/utmp are not removed when 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.

  * screen may give a strange warning when your tty has no utmp entry.

Reporting Bugs
==============

If you find a bug in Screen, please send electronic mail to screen@uni-erlangen.de, and also to bug-gnu-utils@prep.ai.mit.edu.  Include the version number of 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 screen with the -DDEBUG -DTMPTEST options enabled, reproduce the bug, and have a look at the debug output written to the directory /tmp/debug. If necessary quote suspect passages from the debug output and show the contents of your config.h if it matters.

Installation
************

Since 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.

Socket Directory
================

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

Compiling Screen
================

To compile and install screen:

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

sh ./configure

This will create a config.h and Makefile for your machine. If configure fails for some reason, then look at the examples and comments found in the Makefile.in and config.h.in templates. Rename config.status to config.status.MACHINE when you want to keep configuration data for multiple architectures. Runing sh ./config.status.MACHINE recreates your configuration significantly faster than rerunning configure. Read through the "User Configuration" section of 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 screenrc-file and for the socket directory. Check the compiler used in Makefile, the prefix path where to install screen. Then run

make

If make fails to produce one of the files term.h, comm.h or tty.c, then use FILENAME.X.dist instead. For additional information about installation of screen refer to the file INSTALLATION, coming with this package.

Command Index
*************

This is a list of all the commands supported by screen.

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.