path: root/doc/screen.1

.\" vi:set wm=5
.TH SCREEN 1 "15 Oct 1995"
.if n .ds Q \&"
.if n .ds U \&"
.if t .ds Q ``
.if t .ds U ''
.UC 4
.SH NAME
screen \- screen manager with VT100/ANSI terminal emulation


.SH SYNOPSIS
.B screen
[
.B \-\fIoptions\fP
] [
.B \fIcmd\fP
[
.B \fIargs\fP
] ]
.br
.B screen \-r
[ [\fIpid.\fP]\fItty\fP[\fI.host\fP] ]
.ta .5i 1.8i


.SH DESCRIPTION
.I 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 a 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 moving text regions between
windows.
.PP
When
.I 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 existing windows, view a list of
windows, turn output logging on and off, copy-and-paste text between
windows, view the scrollback history, switch between windows
in whatever manner you wish, etc.
When a program terminates,
.I screen
(per default) kills the window that contained it.
If this window was in the foreground, the display switches to the previous
window; if none are left,
.I screen
exits.
.PP
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 and all the key bindings can be fully customized
to be anything you like, though they are always two characters in length.
.PP
The standard way to create a new window is to type \*QC-a c\*U.
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
\*QC-a :\*U command line) and
then using it just like the \*QC-a c\*U command.
In addition, new windows can be created by running a command like:
.IP
screen emacs prog.c
.PP
from a shell prompt within a previously created window.
This will not run another copy of
.IR 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.
.PP
If \*Q/etc/utmp\*U is writable by
.IR screen ,
an appropriate record will be written to this file for each window, and
removed when the window is terminated.
This is useful for working with \*Qtalk\*U, \*Qscript\*U, \*Qshutdown\*U,
\*Qrsend\*U, \*Qsccs\*U and other similar programs that use the utmp
file to determine who you are. As long as
.I screen
is active on your terminal,
the terminal's own record is removed from the utmp file. See also \*QC-a L\*U.


.SH GETTING STARTED
Before you begin to use
.I 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
.IR tset
for example.)
.PP
If you're impatient and want to get started without doing a lot more reading,
you should remember this one command:  \*QC-a ?\*U.
Typing these two characters will display a list of the available
.I screen
commands and their bindings. Each keystroke is discussed in
the section \*QDEFAULT KEY BINDINGS\*U. The manual section \*QCUSTOMIZATION\*U
deals with the contents of your .screenrc.
.PP
If your terminal is a \*Qtrue\*U auto-margin terminal (it doesn't allow
the last position on the screen to be updated without scrolling the
screen) consider to use a version of your terminal's termcap that has
automatic margins turned \fIoff\fP. This will ensure an accurate and
optimal update of the screen in all circumstances. Most terminals
nowadays have \*Qmagic\*U margins (automatic margins plus usable last
column). This is the VT100 style type and perfectly suited for
\fIscreen\fP.
If all you've got is a \*Qtrue\*U auto-margin terminal \fIscreen\fP
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.


.SH "COMMAND-LINE OPTIONS"
Screen has the following command-line options:
.TP 5
.B \-a
include \fIall\fP capabilities (with some minor exceptions) in each
window's termcap, even if
.I screen
must redraw parts of the display in order to implement a function.
.TP 5
.B \-A
Adapt the sizes of all windows to the size of the current terminal.
By default,
.I screen
tries to restore its old window sizes when attaching to resizable terminals
(those with \*QWS\*U in its description, e.g. suncmd or some xterm).
.TP 5
.BI "\-c " file
override the default configuration file from \*Q$HOME/.screenrc\*U
to \fIfile\fP.
.TP 5
.BR \-d | \-D " [" \fIpid.tty.host ]
does not start
.IR screen ,
but detaches the elsewhere running
.I screen
session. It has the same effect as typing \*QC-a d\*U from
.I screen's
controlling terminal. \fB\-D\fP is the equivalent to the power detach key.
If no session can be detached, this option is ignored.
The combination \*Qscreen \-D \-r\*U can be used to `transport' the elsewhere
running session to this terminal and logout there.
Note: It is a good idea to have the status of your sessions checked by means of
\*Qscreen \-list\*U.
.TP 5
.BI "\-e " xy
specifies the command character to be \fIx\fP and the character generating a
literal command character to \fIy\fP (when typed after the command character).
The default is \*QC-a\*U and `a', which can be specified as \*Q-e^Aa\*U.
When creating a
.I screen
session, this option sets the default command character. In a multiuser
session all users added will start off with this command character. But
when attaching to an already running session, this option changes only
the command character of the attaching user.
This option is equivalent to either the commands \*Qdefescape\*U or
\*Qescape\*U respectively.
.TP 5
.BR \-f\fP ", " \-fn ", and " \-fa
turns flow-control on, off, or \*Qautomatic switching mode\*U.
This can also be defined through the \*Qdefflow\*U .screenrc command.
.TP 5
.BI "\-h " num
Specifies the history scrollback buffer to be \fInum\fP lines high.
.TP 5
.B \-i
will cause the interrupt key (usually C-c) to interrupt the display
immediately when flow-control is on.
See the \*Qdefflow\*U .screenrc command for details.
The use of this option is discouraged.
.TP 5
.BR \-l " and " \-ln
turns login mode on or off (for /etc/utmp updating).
This can also be defined through the \*Qdeflogin\*U .screenrc command.
.TP 5
.BR \-ls " and " \-list
does not start
.IR screen ,
but prints a list of
.I pid.tty.host
strings identifying your
.I screen
sessions.
Sessions marked `detached' can be resumed with \*Qscreen -r\*U. 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. Remove sessions with the \fB-wipe\fP option.
.TP 5
.B \-L
tells
.I screen
your auto-margin terminal has a writable last-position on
the screen.
This can also be set in your .screenrc by specifying `LP' in a \*Qtermcap\*U
command.
.TP 5
.B \-m
causes
.I screen
to ignore the $STY environment variable. With \*Qscreen -m\*U creation of
a new session is enforced, regardless whether
.I screen
is called from within another
.I screen
session or not.
.TP 5
.B \-O
selects a more optimal output mode for your terminal rather than true VT100
emulation (only affects auto-margin terminals without `LP').
This can also be set in your .screenrc by specifying `OP' in a \*Qtermcap\*U
command.
.TP 5
.BR \-r " [" \fIpid.tty.host ]
resumes a detached
.I screen
session.
No other options (except \*Q-d -r\*U or \*Q-D -r\*U) may be specified, though
an optional prefix of [\fIpid.\fP]\fItty.host\fP
may be needed to distinguish between multiple detached
.I screen
sessions.
.TP 5
.B \-R
attempts to resume the first detached
.I screen
session it finds.
If successful, all other command-line options are ignored.
If no detached session exists, starts a new session using the specified
options, just as if
.B \-R
had not been specified. The option is set by default if
.I screen
is run as a login-shell.
.TP 5
.B \-s
sets the default shell to the program specified, instead of the value
in the environment variable $SHELL (or \*Q/bin/sh\*U if not defined).
This can also be defined through the \*Qshell\*U .screenrc command.
.TP 5
.BI "\-S " sessionname
When creating a new session, this option can be used to specify a
meaningful name for the session. This name identifies the session for
\*Qscreen -list\*U and \*Qscreen -r\*U actions. It substitutes the
default [\fItty.host\fP] suffix.
.TP 5
.BI "\-t " name
sets the title (a.\|k.\|a.) for the default shell or specified program.
See also the \*Qshelltitle\*U .screenrc command.
.TP 5
.B \-v
Print version number.
.TP 5
.B \-wipe
does the same as \*Qscreen -ls\*U, but removes destroyed sessions instead of
marking them as `dead'.
.TP 5
.B \-x
Attach to a not detached
.I screen
session. (Multi display mode).


.SH "DEFAULT KEY BINDINGS"
.ta 12n 26n
As mentioned, each
.I screen
command consists of a
\*QC-a\*U 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 \*QC-a a\*U; see below), thus, \*QC-a c\*U as well as \*QC-a C-c\*U can
be used to create a window. See section \*QCUSTOMIZATION\*U for a description
of the command.
.PP
.TP 26n
The following table shows the default key bindings:
.IP "\fBC-a '\fP"
.PD 0
.IP "\fBC-a ""\fP	(select)"
.PD
Prompt for a window name or number to switch to.
.IP "\fBC-a 0\fP	(select 0)"
.PD 0
.IP "\fB ... \fP	   ..."
.IP "\fBC-a 9\fP	(select 9)"
.PD
Switch to window number 0 \- 9.
.IP "\fBC-a C-a\fP	(other)"
Toggle to the window displayed previously.
Note that this binding defaults to the command character typed twice,
unless overridden; for instance, if you use the option \*Q\fB\-e]x\fP\*U,
this command becomes \*Q]]\*U, not \*Q]C-a\*U.
.IP "\fBC-a a\fP	(meta)"
Send the command character (C-a) to window. See \fIescape\fP command.
.IP "\fBC-a A\fP	(title)"
Allow the user to enter a name for the current window.
.IP "\fBC-a b\fP"
.PD 0
.IP "\fBC-a C-b\fP	(break)"
.PD
Send a break to window.
.IP "\fBC-a B\fP	(pow_break)"
Reopen the terminal line and send a break.
.IP "\fBC-a c\fP"
.PD 0
.IP "\fBC-a C-c\fP	(screen)"
.PD
Create a new window with a shell and switch to that window.
.IP "\fBC-a C\fP	(clear)"
Clear the screen.
.IP "\fBC-a d\fP"
.PD 0
.IP "\fBC-a C-d\fP	(detach)"
.PD
Detach
.I screen
from this terminal.
.IP "\fBC-a D D\fP	(pow_detach)"
Detach and logout.
.IP "\fBC-a f\fP"
.PD 0
.IP "\fBC-a C-f\fP	(flow)"
.PD
Toggle flow \fIon\fP, \fIoff\fP or \fIauto\fP.
.IP "\fBC-a C-g\fP	(vbell)"
Toggles
.I screen's
visual bell mode.
.IP "\fBC-a h\fP	(hardcopy)"
.PD
Write a hardcopy of the current window to the file \*Qhardcopy.\fIn\fP\*U.
.IP "\fBC-a H\fP	(log)"
Begins/ends logging of the current window to the file \*Qscreenlog.\fIn\fP\*U.
.IP "\fBC-a i\fP"
.PD 0
.IP "\fBC-a C-i\fP	(info)"
.PD
Show info about this window.
.IP "\fBC-a k\fP"
.PD 0
.IP "\fBC-a C-k\fP	(kill)"
.PD
Destroy current window.
.IP "\fBC-a l\fP"
.PD 0
.IP "\fBC-a C-l\fP	(redisplay)"
.PD
Fully refresh current window.
.IP "\fBC-a L\fP	(login)"
Toggle this windows login slot. Available only if
.I screen
is configured to update the utmp database.
.IP "\fBC-a m\fP"
.PD 0
.IP "\fBC-a C-m\fP	(lastmsg)"
.PD
Repeat the last message displayed in the message line.
.IP "\fBC-a M\fP	(monitor)"
Toggles monitoring of the current window.
.IP "\fBC-a space\fP"
.PD 0
.IP "\fBC-a n\fP"
.IP "\fBC-a C-n\fP	(next)"
.PD
Switch to the next window.
.IP "\fBC-a N\fP	(number)"
Show the number (and title) of the current window.
.IP "\fBC-a backspace\fP"
.PD 0
.IP "\fBC-a h\fP"
.IP "\fBC-a p\fP"
.IP "\fBC-a C-p\fP	(prev)"
.PD
Switch to the previous window (opposite of \fBC-a n\fP).
.IP "\fBC-a q\fP"
.PD 0
.IP "\fBC-a C-q\fP	(xon)"
.PD
Send a control-q to the current window.
.IP "\fBC-a r\fP"
.PD 0
.IP "\fBC-a C-r\fP	(wrap)"
.PD
Toggle the current window's line-wrap setting (turn the current window's
automatic margins on and off).
.IP "\fBC-a s\fP"
.PD 0
.IP "\fBC-a C-s\fP	(xoff)"
.PD
Send a control-s to the current window.
.IP "\fBC-a t\fP"
.PD 0
.IP "\fBC-a C-t\fP	(time)"
.PD
Show system information.
.IP "\fBC-a v\fP	(version)"
.PD
Display the version and compilation date.
.IP "\fBC-a C-v\fP	(digraph)"
.PD
Enter digraph.
.IP "\fBC-a w\fP"
.PD 0
.IP "\fBC-a C-w\fP	(windows)"
.PD
Show a list of window.
.IP "\fBC-a W\fP	(width)"
Toggle 80/132 columns.
.IP "\fBC-a x\fP"
.PD 0
.IP "\fBC-a C-x\fP	(lockscreen)"
.PD
Lock this terminal.
.IP "\fBC-a z\fP"
.PD 0
.IP "\fBC-a C-z\fP	(suspend)"
.PD
Suspend
.IR screen .
Your system must support BSD-style job-control.
.IP "\fBC-a Z\fP	(reset)"
Reset the virtual terminal to its \*Qpower-on\*U values.
.IP "\fBC-a .\fP	(dumptermcap)"
Write out a \*Q.termcap\*U file.
.IP "\fBC-a ?\fP	(help)"
Show key bindings.
.IP "\fBC-a C-\e\fP	(quit)"
Kill all windows and terminate
.IR screen .
.IP "\fBC-a :\fP	(colon)"
Enter command line mode.
.IP "\fBC-a [\fP"
.PD 0
.IP "\fBC-a C-[\fP"
.IP "\fBC-a esc\fP	(copy)"
.PD
Enter copy/scrollback mode.
.IP "\fBC-a ]\fP	(paste .)"
.PD
Write the contents of the paste buffer to the stdin queue of the
current window.
.IP "\fBC-a {\fP
.PD 0
.IP "\fBC-a }\fP	(history)"
.PD
Copy and paste a previous (command) line.
.IP "\fBC-a >\fP	(writebuf)"
Write paste buffer to a file.
.IP "\fBC-a <\fP	(readbuf)"
Reads the screen-exchange file into the paste buffer.
.IP "\fBC-a =\fP	(removebuf)"
Removes the file used by \fBC-a <\fP and \fPC-a >\fP.
.IP "\fBC-a ,\fP	(license)"
Shows where
.I screen
comes from, where it went to and why you can use it.
.IP "\fBC-a _\fP	(silence)"
Start/stop monitoring the current window for inactivity.


.SH CUSTOMIZATION
The \*Qsocket directory\*U defaults either to $HOME/.screen or simply to
/tmp/screens or preferably to /usr/local/screens chosen at compile-time. If
.I screen
is installed setuid-root, then the administrator
should compile
.I screen
with an adequate (not NFS mounted) socket directory. If
.I screen
is not running setuid-root, the user can specify any mode 777 directory
in the environment variable $SCREENDIR.
.PP
When
.I screen
is invoked, it executes initialization commands from the files
\*Q/usr/local/etc/screenrc\*U and
\*Q.screenrc\*U in the user's home directory. These are the \*Qprogrammer's
defaults\*U that can be overridden in the following ways: for the
global screenrc file
.I screen
searches for the environment variable $SYSSCREENRC (this override feature
may be disabled at compile-time). The user specific
screenrc file is searched in $ISCREENRC, then $SCREENRC, then $HOME/.iscreenrc
and finally defaults to $HOME/.screenrc. The command line option \fB-c\fP takes
precedence over the above user screenrc files.
.PP
Commands in these files are used to set options, bind functions to
keys, and to automatically establish one or more windows at the
beginning of your
.I screen
session.
Commands are listed one per line, with empty lines being ignored.
A command's arguments are separated by tabs or spaces, and may be
surrounded by single or double quotes.
A `#' turns the rest of the line into a comment, except in quotes.
Unintelligible lines are warned about and ignored.
Commands may contain references to environment variables. The
syntax is the shell-like "$VAR " or "${VAR}". Note that this causes
incompatibility with previous
.I screen
versions, as now the '$'-character has to be protected with '\e' if no
variable substitution shall be performed. A string in single-quotes is also
protected from variable substitution.
.PP
Customization can also be done 'on-line'. To enter the command mode type
`C-a :'. Note that commands starting with \*Qdef\*U change default values,
while others change current settings.
.PP
The following commands are available:
.sp
.ne 3
.BI acladd " usernames"
.PP
Enable users to fully access this screen session. \fIUsernames\fP can be one
user or a comma seperated list of users. This command enables to attach to the
.I screen
session and performs the equivalent of `aclchg \fIusernames\fP +rwx \&"#?\&"'.
executed. To add a user with restricted access, use the `aclchg' command below.
Multi user mode only.
.sp
.ne 3
.BI aclchg " usernames permbits list"
.PP
Change permissions for a comma seperated list of users. Permission bits are
represented as `r', `w' and `x'. Prefixing `+' grants the permission, `-'
removes it. The third parameter is a comma seperated list of commands and/or
windows (specified either by number or title). The special list `#' refers to
all windows, `?' to all commands. if \fIusernames\fP consists of a single `*',
all known users are affected.
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.
To withdraw the writelock from another user in window 2:
`aclchg \fIusername\fP -w+w 2'.
To allow readonly access to the session: `aclchg \fIusername\fP
-w \&"#\&"'. As soon as a user's name is known to
.I screen
he can attach to the session and (per default) has full permissions for all
command and windows. Execution permission for the acl commands, `at' and others
should also be removed or the user may be able to regain write permission.
Multi user mode only.
.sp
.ne 3
.BI acldel " username"
.PP
Remove a user from
.IR screen 's
access control list. If currently attached, all the
user's displays are detached from the session. He cannot attach again.
Multi user mode only.
.sp
.ne 3
.BI activity " message"
.PP
When any activity occurs in a background window that is being monitored,
.I screen
displays a notification in the message line.
The notification message can be re-defined by means of the \*Qactivity\*U
command.
Each occurrence of `%' in \fImessage\fP 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
.sp
	'Activity in window %'
.sp
Note that monitoring is off for all windows by default, but can be altered
by use of the \*Qmonitor\*U command (C-a M).
.sp
.ne 3
.BR "allpartial on" | off
.PP
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 \*Qallpartial off\*U.  This is a global flag that immediately takes effect
on all windows overriding the \*Qpartial\*U settings. It does not change the
default redraw behaviour of newly created windows.
.sp
.ne 3
.BR "at " "[\fIidentifier\fP][" "#\fP|\fP*\fP|\fP%\fP] "
.IR "command " [ args " ... ]"
.PP
Execute a command at other displays or windows as if it had been entered there.
\*QAt\*U 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 `\fIidentifier\fP*' 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 `\fIidentifier\fP%' identifier
is matched against displays. Displays are named after the ttys they
attach. The prefix `/dev/' or `/dev/tty' may be omitted from the identifier.
If \fIidentifier\fP 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. Caution: Permission is checked for the owners or the
affected display(s), not for the initiator of the `at' command.
.sp
.ne 3
.BR "autodetach on" | off
.PP
Sets whether
.I screen
will automatically detach upon hangup, which
saves all your running programs until they are resumed with a
.B "screen -r"
command.
When turned off, a hangup signal will terminate
.I screen
and all the processes it contains. Autodetach is on by default.
.sp
.ne 3
.BR "autonuke on" | off
.PP
Sets whether a clear screen sequence should nuke all the output
that has not been written to the terminal. See also
\*Qobuflimit\*U.
.sp
.ne 3
.BI "bell " message
.PP
When a bell character is sent to a background window,
.I screen
displays a notification in the message line.
The notification message can be re-defined by means of the \*Qbell\*U
command.
Each occurrence of `%' in \fImessage\fP 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
.sp
	'Bell in window %'
.sp
An empty message can be supplied to the \*Qbell\*U command to suppress
output of a message line (bell "").
.sp
.ne 3
.BI "bind " key
.RI [ command " [" args ]]
.PP
Bind a command to a key.
By default, most of the commands provided by
.I screen
are bound to one or more keys as indicated in the \*QDEFAULT KEY BINDINGS\*U
section, e.\|g. the
command to create a new window is bound to \*QC-c\*U and \*Qc\*U.
The \*Qbind\*U command can be used to redefine the key bindings and to
define new bindings.
The \fIkey\fP argument is either a single character, a two-character sequence
of the form \*Q^x\*U (meaning \*QC-x\*U), a backslash followed by an octal
number (specifying the ASCII code of the character), or a backslash followed
by a second character, such as \*Q\e^\*U or \*Q\e\e\*U.
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 \fIcommand\fP argument can be any command listed in this section.
.PP
Some examples:
.PP
.nf
	bind ' ' windows
	bind ^f screen telnet foobar
	bind \e033 screen -ln -t root -h 1000 9 su
.fi
.PP
would bind the space key to the command that displays a list
of windows (so that the command usually invoked by \*QC-a C-w\*U
would also be available as \*QC-a space\*U),
bind \*QC-f\*U to the command \*Qcreate a window with a TELNET
connection to foobar\*U, and bind \*Qescape\*U to the command
that creates an non-login window with a.\|k.\|a. \*Qroot\*U in slot #9, with
a super-user shell and a scrollback buffer of 1000 lines.
.sp
.ne 3
.B bindkey
.RB [ -d ]
.RB [ -m ]
.RB [ -a ]
.RB [[ -k | -t ]
.I string
.RI [ "cmd args" ]]
.PP
This command manages screen's input translation tables. Every
entry in one of the tables tells screen how to react if a certain
sequence of characters is encountered. There are three tables:
one that should contain actions programmed by the user, one for
the default actions used for terminal emulation and one for
screen's copy mode to do cursor movement. See section
\*QINPUT TRANSLATION\*U for a list of default key bindings.
.br
If the
.B -d
option is given, bindkey modifies the default table,
.B -m
changes the copy mode table
and with neither option the user table is selected.
The argument
.I string
is the sequence of characters to which an action is bound. This
can either be a fixed string or a termcap keyboard capability
name (selectable with the
.B -k
option).
.br
Some keys on a VT100 terminal can send a different
string if application mode is turned on (e.g the cursor keys).
Such keys have two entries in the translation table. You can
select the application mode entry by specifying the
.B -a
option.
.br
The
.B -t
option tells screen not to do intercharacter timing. One cannot
turn off the timing if a termcap capabilty is used.
.br
.I Cmd
can be any of screen's commands with an arbitrary number of
.IR args .
If
.I cmd
is omitted the keybinding is removed from the table.
.br
Here are some examples of keyboard bindings:
.sp
.nf
        bindkey -d
.fi
Show all of the default key bindings. The application mode entries
are marked with [A].
.sp
.nf
        bindkey -k k1 select 1
.fi
Make the "F1" key switch to window one.
.sp
.nf
        bindkey -t foo stuff barfoo
.fi
Make "foo" an abrevation of the word "barfoo". Timeout is disabled
so that users can type slowly.
.sp
.nf
        bindkey "\e024" mapdefault
.fi
This keybinding makes \*Q^T\*U an escape character for keybindings. If
you did the above \*Qstuff barfoo\*U binding, you can enter the word
\*Qfoo\*U by typing \*Q^Tfoo\*U. If you want to insert a \*Q^T\*U
you have to press the key twice (i.e. escape the escape binding).
.sp
.nf
        bindkey -k F1 command
.fi
Make the F11 (not F1!) key an alternative screen
escape (besides ^A).
.sp
.ne 3
.B break
.RI [ duration ]
.PP
Send a break signal for \fIduration\fP*0.25 seconds to this window.
Most useful if a character device is
attached to the window rather than a shell process.
.sp
.ne 3
.B bufferfile
.RI [ exchange-file ]
.PP
Change the filename used for reading and writing with the paste buffer.
If the optional argument to the \*Qbufferfile\*U command is omitted,
the default setting (\*Q/tmp/screen-exchange\*U) is reactivated.
The following example will paste the system's password file into
the
.I screen
window (using the paste buffer, where a copy remains):
.PP
.nf
	C-a : bufferfile /etc/passwd
	C-a < C-a ]
	C-a : bufferfile
.fi
.sp
.ne 3
.BR "c1 " [ on | off ]
.PP
Change c1 code processing. \*QC1 on\*U tells screen to treat
the input characters between 128 and 159 as control functions.
Such an 8-bit code is normally the same as ESC followed by the
corresponding 7-bit code. The default setting is to process c1
codes and can be changed with the \*Qdefc1\*U command. 
Users with fonts that have usable characters in the
c1 positions may want to turn this off.
.sp
.ne 3
.BI "charset " set
.PP
Change the current character set slot designation and charset
mapping.  The first four character of
.I set
are treated as charset designators while the fifth and sixth
character must be in range '0' to '3' and set the GL/GR charset
mapping. On every position a '.' may be used to indicate that
the corresponding charset/mapping should not be changed
(\fIset\fP is padded to six characters internally by appending '.'
chars). New windows have "BBBB02" as default charset, unless a
\*Qkanji\*U command is active.
.br
The current setting can be viewed with the \*Qinfo\*U command.
.sp
.ne 3
.B chdir
.RI [ directory ]
.PP
Change the \fIcurrent directory\fP of
.I 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 \*Qscreen\*U command
from within \*Q.screenrc\*U or by means of \*QC-a : screen ...\*U
or \*QC-a c\*U use this as their default directory.
Without a chdir command, this would be the directory from which
.I screen
was invoked.
Hardcopy and log files are always written to the \fIwindow's\fP default
directory, \fInot\fP 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.
.sp
.ne 3
.B clear
.PP
Clears the current window and saves its image to the scrollback buffer.
.sp
.ne 3
.B colon
.PP
Allows you to enter \*Q.screenrc\*U command lines. Useful
for on-the-fly modification of key bindings,
specific window creation and changing settings. Note that the \*Qset\*U
keyword no longer exists! Usually commands affect the current window rather
than default settings for future windows. Change defaults with commands
starting with 'def...'.

If you consider this as the `Ex command mode' of
.IR screen ,
you may regard \*QC-a esc\*U (copy mode) as its `Vi command mode'.
.sp
.ne 3
.B command
.PP
This command has the same effect as typing the screen escape
character (^A). It is probably only useful for key bindings.
See also \*Qbindkey\*U.
.sp
.ne 3
.BR "console " [ on | off ]
.PP
Grabs or ungrabs the machines console output to a window.
.sp
.ne 3
.B copy
.PP
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:
.br
.IR "Movement keys" :
.br
.in +4n
.ti -2n
\fBh\fP, \fBj\fP, \fBk\fP, \fBl\fP move the cursor line by line or
column by column.
.br
.ti -2n
\fB0\fP, \fB^\fP and \fB$\fP move to the leftmost column, to the first or last
non-whitespace character on the line.
.br
.ti -2n
\fBH\fP, \fBM\fP and \fBL\fP move the cursor to the leftmost column
of the top, center or bottom line of the window.
.br
.ti -2n
\fB+\fP and \fB\-\fP positions one line up and down.
.br
.ti -2n
\fBG\fP moves to the specified absolute line (default: end of buffer).
.br
.ti -2n
\fB|\fP moves to the specified absolute column.
.br
.ti -2n
\fBw\fP, \fBb\fP, \fBe\fP move the cursor word by word.
.br
.ti -2n
\fBC-u\fP and \fBC-d\fP scroll the display up/down by the specified amount of
lines while preserving the cursor position. (Default: half screen-full).
.br
.ti -2n
\fBC-b\fP and \fBC-f\fP scroll the display up/down a full screen.
.br
.ti -2n
\fBg\fP moves to the beginning of the buffer.
.br
.ti -2n
\fB%\fP jumps to the specified percentage of the buffer.
.br
.ti -4n

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

.br
.ti -4n
.IR Marking :
.br
The copy range is specified by setting two marks. The text between these marks
will be highlighted. Press
.br
.ti -2n
\fBspace\fP to set the first or second mark
respectively.
.br
.ti -2n
\fBY\fP and \fBy\fP used to mark one whole line or to mark from
start of line.
.br
.ti -2n
\fBW\fP marks exactly one word.
.br
.ti -4n
.IR "Repeat count" :
.br
Any of these commands can be prefixed with a repeat count number by pressing
digits
.br
.ti -2n
\fB0\fP..\fB9\fP which
is taken as a repeat count.
.br
Example: \*QC-a C-[ H 10 j 5 Y\*U will copy lines
11 to 15 into the paste buffer.
.br
.ti -4n
.IR Searching :
.ti -2n
\fB/\fP \fIVi\fP-like search forward.
.ti -2n
\fB?\fP \fIVi\fP-like search backward.
.ti -2n
\fBC-a s\fP \fIEmacs\fP style incremental search forward.
.ti -2n
\fBC-r\fP \fIEmacs\fP style reverse i-search.
.ti -4n
.IR Specials :
.br
There are however some keys that act differently than in
.IR vi .
.I Vi
does not allow one to yank rectangular blocks of text, but
.I screen
does. Press
.br
.ti -2n
\fBc\fP or \fBC\fP to set the left or right margin respectively. If no repeat count is
given, both default to the current cursor position.
.br
Example: Try this on a rather full text screen:
\*QC-a [ M 20 l SPACE c 10 l 5 j C SPACE\*U.

This moves one to the middle line of the screen, moves in 20 columns left,
marks the beginning of the paste buffer, sets the left column, moves 5 columns
down, sets the right column, and then marks the end of
the paste buffer. Now try:
.br
\*QC-a [ M 20 l SPACE 10 l 5 j SPACE\*U

and notice the difference in the amount of text copied.
.br
.ti -2n
\fBJ\fP joins lines. It toggles between
3 modes: lines separated by a newline character (012), lines glued seamless,
lines separated by a single whitespace. Note that you can prepend the newline
character with a carriage return character, by issuing a \*Qcrlf on\*U.
.br
.ti -2n
\fBv\fP is for all the
.I vi
users with \*Q:set numbers\*U \- it toggles the left margin between column 9
and 1. Press
.br
.ti -2n
\fBa\fP before the final space key to toggle in append mode. Thus
the contents of the paste buffer will not be overwritten, but is appended to.
.br
.ti -2n
\fBA\fP toggles in append mode and sets a (second) mark.
.br
.ti -2n
\fB>\fP sets the (second) mark and writes the contents of the paste buffer to
the screen-exchange file (/tmp/screen-exchange per default) once copy-mode is
finished.
.br
This example demonstrates how to dump the whole scrollback buffer
to that file: \*QC-A [ g SPACE G $ >\*U.
.br
.ti -2n
\fBC-g\fP gives information about the current line and column.
.br
.ti -2n
\fBx\fP exchanges the first mark and the current cursor position. You
can use this to adjust an already placed mark.
.br
.ti -2n
\fB@\fP does nothing. Does not even exit copy mode.
.br
.ti -2n
All keys not described here exit copy mode.
.in -4n
.sp
.ne 3
.B copy_reg
.RI [ key ]
.PP
No longer exists, use \*Qreadreg\*U instead.
.sp
.ne 3
.BR "crlf on" | off
.PP
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 (default) only `LF' is used.
.sp
.ne 3
.BR "debug on" | off
.PP
Turns runtime debugging on or off. If
.I screen
has been compiled with option -DDEBUG debugging available and is turned on per
default. Note that this command only affects debugging output from the main
\*QSCREEN\*U process.
.sp
.ne 3
.BR "defc1 on" | off
.PP
Same as the \fBc1\fP command except that the default setting for new
windows is changed. Initial setting is `on'.
.sp
.ne 3
.BR "defautonuke on" | off
.PP
Same as the \fBautonuke\fP 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 dependency on the terminal type.
.sp
.ne 3
.BR "defcharset " [ \fIset ]
.PP
Like the \fBcharset\fP command except that the default setting for
new windows is changed. Shows current default if called without
argument.
.sp
.ne 3
.BI "defescape " xy
.PP
Set the default command characters. This is equivalent to the
\*Qescape\*U except that it is useful multiuser sessions only. In a
multiuser session \*Qescape\*U changes the command character of the
calling user, where \*Qdefescape\*U changes the default command
characters for users that will be added later.
.sp
.ne 3
.BR "defflow on" | off | auto
.RB [ interrupt ]
.PP
Same as the \fBflow\fP command except that the default setting for new windows
is changed. Initial setting is `auto'.
Specifying \*Qdefflow auto interrupt\*U is the same as the command-line options
.B \-fa
and
.BR \-i .
.sp
.ne 3
.BR "defgr on" | off
.PP
Same as the \fBgr\fP command except that the default setting for new
windows is changed. Initial setting is `off'.
.sp
.ne 3
.BR "defhstatus " [ \fIstatus ]
.PP
The hardstatus line that all new windows will get is set to
.I status\fR.
This command is useful to make the hardstatus of every window
display the window number or title or the like.
.I Status
may contain the same directives as in the window messages, but
the directive escape character is '^E' (octal 005) instead of '%'.
This was done to make a misinterpretion of program generated
hardstatus lines impossible.
If the parameter
.I status
is omitted, the current default string is displayed.
Per default the hardstatus line of new windows is empty.
.sp
.ne 3
.BR "defkanji jis" | sjis | euc
.PP
Same as the \fBkanji\fP command except that the default setting for new
windows is changed. Initial setting is `off', i.e. `jis'.
.sp
.ne 3
.BR "deflogin on" | off
.PP
Same as the \fBlogin\fP command except that the default setting for new windows
is changed. This is initialized with `on' as distributed (see config.h.in).
.sp
.ne 3
.BI "defmode " mode
.PP
The mode of each newly allocated pseudo-tty is set to \fImode\fP.
\fIMode\fP is an octal number.
When no \*Qdefmode\*U command is given, mode 0622 is used.
.sp
.ne 3
.BR "defmonitor on" | off
.PP
Same as the \fBmonitor\fP command except that the default setting for new
windows is changed. Initial setting is `off'.
.sp
.ne 3
.BI "defobuflimit " limit
.PP
Same as the \fBobuflimit\fP 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 dependency on the terminal type.
.sp
.ne 3
.BI "defscrollback " num
.PP
Same as the \fBscrollback\fP command except that the default setting for new
windows is changed. Initial setting is 100.
.sp
.ne 3
.BR "defwrap on" | off
.PP
Same as the \fBwrap\fP command except that the default setting for new
windows is changed. Initially line-wrap is on and can be toggled with the
\*Qwrap\*U command (\*QC-a r\*U) or by means of "C-a : wrap on|off".
.sp
.ne 3
.BR "defwritelock on" | off | auto
.PP
Same as the \fBwritelock\fP command except that the default setting for new
windows is changed. Initially writelocks will operate in automatic mode.
.sp
.ne 3
.BR "defzombie " [\fIkeys\fP]
.PP
Synonym to the \fBzombie\fP command. Both currently change the default.
See there.
.sp
.ne 3
.B detach
.PP
Detach the
.I screen
session (disconnect it from the terminal and put it into the background).
This returns you to the shell where you invoked
.IR screen .
A detached
.I screen
can be resumed by invoking
.I screen
with the
.B \-r
option. (See also section \*QCOMMAND-LINE OPTIONS\*U.)
.sp
.ne 3
.BR "digraph " [ \fIpreset ]
.PP
This command prompts the user for a digraph sequence. The next
two characters typed are looked up in a builtin table and the
resulting character is inserted in the input stream. For example,
if the user enters 'a"', an a-umlaut will be inserted. If the
first character entered is a 0 (zero),
.I screen
will treat the following charcters (up to three) as an octal
number instead.  The optional argument
.I preset
is treated as user input, thus one can create an \*Qumlaut\*U key.
For example the command "bindkey ^K digraph '"'" enables the user
to generate an a-umlaut by typing CTRL-K a.
.sp
.ne 3
.B dumptermcap
.PP
Write the termcap entry for the virtual terminal optimized for the currently
active window to the file \*Q.termcap\*U in the user's
\*Q$HOME/.screen\*U directory (or wherever
.I screen
stores its sockets. See the \*QFILES\*U section below).
This termcap entry is identical to the value of the environment variable
$TERMCAP that is set up by
.I screen
for each window. For terminfo based systems you will need to run a converter
like
.IR captoinfo
and then compile the entry with
.IR tic .
.sp
.ne 3
.BR "echo " [ -n ]
.I message
.PP
The echo command may be used to annoy
.I screen
users with a 'message of the
day'. Typically installed in a global /local/etc/screenrc. See also
\*Qsleep\*U.
Echo is also useful for online checking of environment variables.
.sp
.ne 3
.BI "escape " xy
.PP
Set the command character to \fIx\fP and the character generating a literal
command character to \fIy\fP (just like in the \-e option).
Each argument is either a single character, a two-character sequence
of the form \*Q^x\*U (meaning \*QC-x\*U), a backslash followed by an octal
number (specifying the ASCII code of the character), or a backslash followed
by a second character, such as \*Q\e^\*U or \*Q\e\e\*U.
The default is \*Q^Aa\*U.
.sp
.ne 3
.B exec
.RI [[ fdpat ]
.IR "newcommand " [ "args ..." ]]
.PP
Run a subprocess (newcommand) in the current window. The flow of data between
newcommand's 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
.IR 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 (|) is added to
the end of fdpat.
.br
Invoking `exec' without arguments shows name and arguments of the currently
running subprocess in this window.
.br
When a subprocess is running the `kill' command will affect it instead of the
windows process.
.br
Refer to the postscript file `fdpat.ips' for a confusing illustration
of all 21 possible combinations. Each drawing shows the digits 2,1,0
representing the three file descriptors of newcommand. The box marked
`W' is usual pty that has the application-process on its slave side.
The box marked `P' is the secondary pty that now has
.I screen
at its master side.
.sp
Abbreviations:
.br
Whitespace between the word `exec' and fdpat and the command
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 omitted here and can always be replaced by `!'.
.sp
Examples:
.IP
exec ... /bin/sh
.br
exec /bin/sh
.br
!/bin/sh
.PP
Creates another shell in the same window, while the original shell is still
running. Output of both shells is displayed and user input is sent to the new
/bin/sh.
.IP
exec !.. stty 19200
.br
exec ! stty 19200
.br
!!stty 19200
.PP
Set the speed of the window's tty. If your stty command operates on stdout, then
add another `!'.
.IP
exec !..| less
.br
|less
.PP
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
window's process. This works, because
.I less
listens on stderr (a behavior that
.I screen
would not expect without the `|') 
when its stdin is not a tty. 
.I Less 
versions newer than 177 fail miserably here; good old
.I pg
still works.
.IP
!:sed -n s/.*Error.*/\e007/p
.PP
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
.IR screen .
This will cause "Bell in window x" messages, whenever the string "Error"
appears in the window.
.sp
.ne 3
.B flow
.RB [ on | off | "auto\fR]\fP"
.PP
Sets the flow-control mode for this window.
Without parameters it cycles the current window's flow-control setting from
"automatic" to "on" to "off".
See the discussion on \*QFLOW-CONTROL\*U later on in this document for full
details and note, that this is subject to change in future releases.
Default is set by `defflow'.
.sp
.ne 3
.BR "gr " [ on | off ]
.PP
Turn GR charset switching on/off. Whenever screens sees an input
char with an 8th bit set, it will use the charset stored in the
GR slot and print the character with the 8th bit stripped. The
default (see also \*Qdefgr\*U) is not to process GR switching because
otherwise the ISO88591 charset would not work.
.sp
.ne 3
.B hardcopy
.PP
Writes out the currently displayed image to a file \fIhardcopy.n\fP
in the window's default directory, where \fIn\fP is the number
of the current window.
This either appends or overwrites the file if it exists. See below.
.sp
.ne 3
.BR "hardcopy_append on" | off
.PP
If set to "on",
.I screen
will append to the "hardcopy.n" files created by the command \*QC-a h\*U,
otherwise these files are overwritten each time.
Default is `off'.
.sp
.ne 3
.BI "hardcopydir "directory
.PP
Defines a directory where hardcopy files will be placed. If unset, hardcopys
are dumped in
.IR screen 's
current working directory.
.sp
.ne 3
.BR "hardstatus " [ on | off ]
.PP
Toggles the use of the terminal's hardware status line. If "on",
.I 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.
.sp
.ne 3
.BR "height " [ \fIlines\fP ]
.PP
Set the display height to a specified number of lines. When no argument
is given it toggles between 24 and 42 lines display.
.sp
.ne 3
.B help
.PP
Not really a online help, but
displays a help screen showing you all the key bindings.
The first pages list all the internal commands followed by their current
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.
See also \*QDEFAULT KEY BINDINGS\*U section.
.sp
.ne 3
.B history
.PP
Usually users work with a shell that allows easy access to previous commands.
For example csh has the command \*Q!!\*U to repeat the last command executed.
.I Screen
allows you to have a primitive way of re-calling \*Qthe command that
started ...\*U: You just type the first letter of that command, then hit
`C-a {' and
.I 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).
.sp
.ne 3
.B info
.PP
Uses the message line to display some information about the current window:
the cursor position in the form \*Q(column,row)\*U starting with \*Q(1,1)\*U,
the terminal width and height plus the size of the scrollback buffer in lines,
like in \*U(80,24)+50\*U, 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 (\fIG0\fP, \fIG1\fP, \fIG2\fP,
or \fIG3\fP), and in square brackets the terminal character sets that are
currently designated as \fIG0\fP through \fIG3\fP.
For system information use the \*Qtime\*U command.
.sp
.ne 3
.BR ins_reg " [" \fIkey ]
.PP
No longer exists, use \*Qpaste\*U instead.
.sp
.ne 3
.B kanji
.BR jis | euc | sjis
.RB [ jis | euc | sjis\fR]
.PP
Tell screen how to process kanji input/output. The first argument
sets the kanji type of the current window. Each window can emulate
a different type. The optional second parameter tells screen
how to write the kanji codes to the connected terminal. The preferred
method of setting the display type is to use the \*QKJ\*U termcap
entry.
See also \*Qdefkanji\*U, which changes the default setting of a new
window.
.sp
.ne 3
.B kill
.PP
Kill current window.
.br
If there is an `exec' command running then it is killed. Otherwise the process
(shell) running in the window receives a HANGUP condition, the window structure
is removed and
.I screen
switches to the previously displayed window.
When the last window is destroyed,
.I screen
exits.
Note:
.I Emacs
users should keep this command in mind, when killing a line.
It is recommended not to use \*QC-a\*U as the
.I screen
escape key or to rebind kill to \*QC-a K\*U.
.sp
.ne 3
.B lastmsg
.PP
Redisplay the last contents of the message/status line.
Useful if you're typing when a message appears, because  the message goes
away when you press a key (unless your terminal has a hardware status line).
Refer to the commands \*Qmsgwait\*U and \*Qmsgminwait\*U for fine tuning.
.sp
.ne 3
.B license
.PP
Display the disclaimer page. This is done whenever
.I screen
is started without options, which should be often enough. See also
the \*Qstartup_message\*U command.
.sp
.ne 3
.B lockscreen
.PP
Lock this display.
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
.I screen
is started) and is executed with the user's uid and gid.
.sp
.ne 3
.BR "log " [ on | off ]
.PP
Start/stop writing output of the current window to a file
\*Qscreenlog.\fIn\fP\*U in the window's default directory, where \fIn\fP
is the number of the current window. This filename can be changed with
the `logfile' command. If no parameter is given, the state
of logging 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'.
.sp
.ne 3
.BI "logfile " filename
.PP
Defines the name the logfiles will get. The default is
\*Qscreenlog.%n\*U.
.sp
.ne 3
.BR "login " [ on | off ]
.PP
Adds or removes the entry in the utmp database file for the current window.
This controls if the window is `logged in'.
When no parameter is given, the login state of the window is toggled.
Additionally to that toggle, it is convenient having a `log in' and a `log out'
key. E.\|g. `bind I login on' and `bind O login off' will map these
keys to be C-a I and C-a O.
The default setting (in config.h.in) should be \*Qon\*U for a
.I screen
that runs under suid-root.
Use the \*Qdeflogin\*U command to change the default login state for new
windows. Both commands are only present when
.I screen
has been compiled with utmp support.
.sp
.ne 3
.B mapdefault
.PP
Tell screen that the next input character should only be looked up
in the default bindkey table. See also \*Qbindkey\*U.
.sp
.ne 3
.B mapnotnext
.PP
Like mapdefault, but don't even look in the default bindkey table.
.sp
.ne 3
.B maptimeout
.RI [ timo ]
.PP
Set the intercharacter timer for input sequence detection to a timeout
of
.I timo
ms. The default timeout is 300ms. Maptimeout with no arguments shows
the current setting.
See also \*Qbindkey\*U.
.sp
.ne 3
.BI "markkeys " string
.PP
This is a method of changing the keymap used for copy/history mode.
The string is made up of \fIoldchar\fP=\fInewchar\fP pairs which are
separated by `:'. Example: The string \*QB=^B:F=^F\*U will change the
keys `C-b' and `C-f' to the vi style binding (scroll up/down fill page).
This happens to be the default binding for `B' and `F'.
The command \*Qmarkkeys h=^B:l=^F:$=^E\*U would set the mode for an emacs-style
binding.
.sp
.ne 3
.B meta
.PP
Insert the command character (C-a) in the current window's input stream.
.sp
.ne 3
.BR "monitor " [ on | off ]
.PP
Toggles activity monitoring of windows.
When monitoring is turned on and an affected window is switched into the
background, you will receive the activity notification message in the
status line at the first sign of output and the window will also be marked
with an `@' in the window-status display.
Monitoring is initially off for all windows.
.sp
.ne 3
.BI "msgminwait " sec
.PP
Defines the time
.I screen
delays a new message when one message is currently displayed.
The default is 1 second.
.sp
.ne 3
.BI "msgwait " sec
.PP
Defines the time a message is displayed if
.I screen
is not disturbed by other activity. The default is 5 seconds.
.sp
.ne 3
.BR "multiuser on" | off
.PP
Switch between singleuser and multiuser mode. Standard
.I screen
operation is singleuser. In multiuser mode the commands `acladd',
`aclchg' and `acldel'
can be used to enable (and disable) other users accessing this screen.
.sp
.ne 3
.BR "nethack on" | off
.PP
Changes the kind of error messages used by
.IR screen .
When you are familiar with the game \*Qnethack\*U, 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.
.br
This option is only
available if
.I screen
was compiled with the NETHACK flag defined. The
default setting is then determined by the presence of the environment
variable $NETHACKOPTIONS.
.sp
.ne 3
.B next
.PP
Switch to the next window.
This command can be used repeatedly to cycle through the list of windows.
.sp
.ne 3
.BR "number " [ \fIn ]
.PP
Change the current windows number. If the given number \fIn\fP is already
used by another window, both windows exchange their numbers. If no argument is
specified, the current window number (and title) is shown.
.sp
.ne 3
.BR "obuflimit " [ \fIlimit ]
.PP
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.
.sp
.ne 3
.B other
.PP
Switch to the window displayed previously.
.sp
.ne 3
.BR "partial on" | off
.PP
Defines whether the display should be refreshed (as with \fIredisplay\fP) after
switching to the current window. This command only affects the current window.
To immediately affect all windows use the \fIallpartial\fP command.
Default is `off', of course.  This default is fixed, as there is currently no
\fIdefpartial\fP command.
.sp
.ne 3
.BR "password " [ \fIcrypted_pw ]
.PP
Present a crypted password in your \*Q.screenrc\*U file and
.I screen
will ask
for it, whenever someone attempts to resume a detached. This is useful
if you have privileged programs running under
.I screen
and you want to protect your session from reattach attempts by another user
masquerading as your uid (i.e. any superuser.)
If no crypted password is specified,
.I screen
prompts twice for typing a
password and places its encryption in the paste buffer.
Default is `none', this disables password checking.
.sp
.ne 3
.BR paste
.RI [ registers " [" dest_reg ]]
.PP
Write the (concatenated) contents of the specified registers to the stdin queue
of the current window. The register '.' is treated as the
paste buffer. If no parameter is given the user is prompted for a single
register to paste.
The paste buffer can be filled with the \fIcopy\fP, \fIhistory\fP and
\fIreadbuf\fP commands.
Other registers can be filled with the \fIregister\fP, \fIreadreg\fP and
\fIpaste\fP commands.
If \fIpaste\fP is called with a second argument, the contents of the specified
registers is pasted into the named destination register rather than
the window. If '.' is used as the second argument, the displays paste buffer is
the destination.
Note, that \*Qpaste\*U uses a wide variety of resources: Whenever a second
argument is specified no current window is needed. When the source specification
only contains registers (not the paste buffer) then there need not be a current
display (terminal attached), as the registers are a global resource. The
paste buffer exists once for every user.
.sp
.ne 3
.BR "pastefont " [ on | off ]
.PP
Tell screen to include font information in the paste buffer. The
default is not to do so. This command is especially usefull for
multi character fonts like kanji.
.sp
.ne 3
.B pow_break
.PP
Reopen the window's terminal line and send a break condition. See `break'.
.sp
.ne 3
.B pow_detach
.PP
Power detach.
Mainly the same as \fIdetach\fP, but also sends a HANGUP signal to
the parent process of
.IR screen .
CAUTION: This will result in a logout, when
.I screen
was started from your login shell.
.sp
.ne 3
.BI "pow_detach_msg " message
.PP
The \fImessage\fP specified here is output whenever a `Power detach' was
performed. It may be used as a replacement for a logout message or to reset
baud rate, etc.
.sp
.ne 3
.B prev
.PP
Switch to the window with the next lower number.
This command can be used repeatedly to cycle through the list of windows.
.sp
.ne 3
.B printcmd
.RI [ cmd ]
.PP
If
.I cmd
is not an empty string, screen will not use the terminal capabilities
\*Qpo/pf\*U if it detects an ansi print sequence
.BR "ESC [ 5 i" ,
but pipe the output into
.IR cmd .
This should normally be a command like \*Qlpr\*U or
\*Q'cat > /tmp/scrprint'\*U.
.B printcmd
without a command displays the current setting.
The ansi sequence
.B "ESC \e"
ends printing and closes the pipe.
.br
Warning: Be careful with this command! If other user have write
access to your terminal, they will be able to fire off print commands.
.sp
.ne 3
.BR process " [" \fIkey ]
.PP
Stuff the contents of the specified register into \fIscreen\fP's
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 user's
keyboard. This command can be used to bind multiple actions to a single key.
.sp
.ne 3
.B quit
.PP
Kill all windows and terminate
.IR screen .
Note that on VT100-style terminals the keys C-4 and C-\e are identical.
This makes the default bindings dangerous:
Be careful not to type C-a C-4 when selecting window no. 4.
Use the empty bind command (as in \*Qbind '^\e'\*U) to remove a key binding.
.sp
.ne 3
.B readbuf
.PP
Reads the contents of the current screen-exchange file into the paste buffer.
See also \*Qbufferfile\*U command.
.sp
.ne 3
.B readreg
.RI [ register " [" filename ]]
.PP
Does one of two things, dependent on number of arguments: with zero or one
arguments it it duplicates the paste buffer contents into the register specified
or entered at the prompt. With two arguments it reads the contents of the named
file into the register, just as \fIreadbuf\fP reads the screen-exchange file
into the paste buffer.
The following example will paste the system's password file into
the screen window (using register p, where a copy remains):
.PP
.nf
	C-a : readreg p /etc/passwd
	C-a : paste p
.fi
.sp
.ne 3
.B redisplay
.PP
Redisplay the current window. Needed to get a full redisplay when in
partial redraw mode.
.sp
.ne 3
.BI "register " "key string"
.PP
Save the specified \fIstring\fP to the register \fIkey\fP. See also the
\*Qpaste\*U command.
.sp
.ne 3
.B "removebuf"
.PP
Unlinks the screen-exchange file used by the commands \*Qwritebuf\*U and
\*Qreadbuf\*U.
.sp
.ne 3
.B "reset"
.PP
Reset the virtual terminal to its \*Qpower-on\*U values. Useful when strange
settings (like scroll regions or graphics character set) are left over from
an application.
.sp
.ne 3
.B "screen \fP[\fI-opts\fP] [\fIn\fP] [\fIcmd\fP [\fIargs\fP]]"
.PP
Establish a new window.
The flow-control options (\fB\-f\fP, \fB\-fn\fP and \fB\-fa\fP),
title (a.\|k.\|a.) option (\fB\-t\fP), login options (\fB-l\fP and \fB-ln\fP)
, terminal type option (\fB-T <term>\fP) and scrollback option (\fB-h\fP <num>)
may be specified for each command.
If an optional number \fIn\fP in the range 0..9 is given, the window
number \fIn\fP 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 \*Qscreen\*U, this command (with the given
arguments) is started in the window; otherwise, a shell is created.
Thus, if your \*Q.screenrc\*U contains the lines
.sp
.nf
	# example for .screenrc:
	screen 1
	screen -fn -t foobar 2 telnet foobar
.fi
.sp
.I 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 \*Qfoobar\*U
in window #2). Note, that unlike previous versions of
.I screen
no additional default window is created when \*Qscreen\*U commands are
included in your \*Q.screenrc\*U file. When the initialization is completed,
.I screen
switches to the last window specified in your .screenrc file or, if none,
opens a default window #0.
.sp
.ne 3
.B "scrollback \fP\fInum\fP"
.PP
Set the size of the scrollback buffer for the current windows to \fInum\fP
lines. The default scrollback is 100 lines.
See also the \*Qdefscrollback\*U command and use \*QC-a i\*U to view the
current setting.
.sp
.ne 3
.BR "select " [ \fIn ]
.PP
Switch to the window with the number \fIn\fP.
If no window number is specified, you get prompted for an
identifier. This can be title (alphanumeric window name) or a number.
When a new window is established, the first available number
is assigned to this window.
Thus, the first window can be activated by \*Qselect 0\*U (there can be no more
than 10 windows present simultaneously unless
.I screen
was compiled with a higher MAXWIN setting).
.sp
.ne
.BR "sessionname " [ \fIname ]
.PP
Rename the current session. Note, that for \*Qscreen -list\*U the
name shows up with the process-id prepended. If the argument \*Qname\*U
is omitted, the name of this session is displayed. Caution: The $STY
environment variables still reflects the old name. This may result in
confusion.
The default is constructed from the tty and host names.
.sp
.ne 3
.B "setenv "
.RI [ var " [" string ]]
.PP
Set the environment variable \fIvar\fP to value \fIstring\fP.
If only \fIvar\fP 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.
.sp
.ne 3
.B "shell \fIcommand\fP"
.PP
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.
.sp
.ne 3
.B "shelltitle \fItitle\fP"
.PP
Set the title for all shells created during startup or by
the C-A C-c command.
For details about what a title is, see the discussion
entitled \*QTITLES (naming windows)\*U.
.sp
.ne 3
.BR "silence " [ on | off "|\fIsec\fP]"
.PP
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.
.sp
.ne 3
.BI "silencewait " sec
.PP
Define the time that all windows monitored for silence should wait before
displaying a message. Default 30 seconds.
.sp
.ne
.B "sleep \fP\fInum\fP"
.PP
This command will pause the execution of a .screenrc file for \fInum\fP seconds.
Keyboard activity will end the sleep.
It may be used to give users a chance to read the messages output by \*Qecho\*U.
.sp
.ne 3
.B "slowpaste \fIusec\fP"
.PP
Define the speed at which text is inserted by the paste ("C-a ]") command.
If the slowpaste value is nonzero text is written character by character.
.I screen
will make a pause of \fIusec\fP milliseconds after each single character write
to allow the application to process its input. Only use slowpaste if your
underlying system exposes flow control problems while pasting large amounts of
text.
.sp
.ne 3
.B sorendition
.RB [ "\fIattr\fR " [ \fIcolor ]]
.PP
Change the way screen does highlighting for text marking and printing
messages.
.I Attr
is a hexadecimal number and describes the attributes (inverse,
underline, ...) the text will get.
.I Color
is a 2 digit number and changes the 
forground/background of the highlighted text.
Some knowledge of screen's internal character representation is
needed to make the characters appear in the desired way. The default
is currently 10 99 (standout, default colors).
.sp
.ne 3
.B "startup_message on\fP|\fBoff"
.PP
Select whether you want to see the copyright notice during startup.
Default is `on', as you probably noticed.
.sp
.ne 3
.B stuff
.I string
.PP
Stuff the string
.I string
in the input buffer of the current window.
This is like the \*Qpaste\*U command but with much less overhead.
You cannot paste
large buffers with the \*stuff\*U command. It is most useful for key
bindings. See also \*Qbindkey\*U.
.sp
.ne 3
.B "suspend"
.PP
Suspend
.IR screen .
The windows are in the `detached' state, while
.IR screen
is suspended. This feature relies on the shell being able to do job control.
.sp
.ne 3
.B "term \fIterm\fP"
.PP
In each window's environment
.I screen
opens, the $TERM variable is set to \*Qscreen\*U by default.
But when no description for \*Qscreen\*U is installed in the local termcap
or terminfo data base, you set $TERM to \- say \-
\*Qvt100\*U. This won't do much harm, as
.I screen
is VT100/ANSI compatible.
The use of the \*Qterm\*U command is discouraged for non-default purpose.
That is, one may want to specify special $TERM settings (e.g. vt100) for the
next \*Qscreen rlogin othermachine\*U command. Use the command \*Qscreen -T vt100
rlogin othermachine\*U rather than setting and resetting the default.
.sp
.ne 3
.BI termcap " term terminal-tweaks"
.RI [ window-tweaks ]
.br
.BI terminfo " term terminal-tweaks"
.RI [ window-tweaks ]
.br
.BI termcapinfo " term terminal-tweaks"
.RI [ window-tweaks ]
.PP
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 works with terminfo-database rather than with
termcap,
.I screen
will understand the `terminfo' command, which has the same effects as
the `termcap' command.  Two separate commands are provided, as there are subtle
syntactic differences, e.g. when parameter interpolation (using `%') is
required. Note that termcap names of the capabilities have to be used
with the `terminfo' command. 
.br
In many cases, where the arguments are valid in both terminfo and termcap
syntax, you can use the command `termcapinfo', which is just a shorthand
for a pair of `termcap' and `terminfo' commands with identical arguments.
.PP
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 \*Qvt\*U.
.PP
Each \fItweak\fP 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
.I screen
understands (see the \*QVIRTUAL TERMINAL\*U
section).
.PP
Some examples:
.IP
termcap xterm*  LP:hs@
.PP
Informs
.I screen
that all terminals that begin with `xterm' have firm auto-margins that
allow the last position on the screen to be updated (LP), but they don't
really have a status line (no 'hs' \- append `@' to turn entries off).
Note that we assume `LP' for all terminal names that start with \*Qvt\*U,
but only if you don't specify a termcap command for that terminal.
.IP
termcap vt*  LP
.br
termcap vt102|vt220  Z0=\eE[?3h:Z1=\eE[?3l
.PP
Specifies the firm-margined `LP' 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.)
.IP
termcap vt100  ""  l0=PF1:l1=PF2:l2=PF3:l3=PF4
.PP
This leaves your vt100 termcap alone and adds the function key labels to
each window's termcap entry.
.IP
termcap h19|z19  am@:im=\eE@:ei=\eEO  dc=\eE[P
.PP
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
.I 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
.I screen
will translate into a line-update for the terminal
(we're pretending it doesn't support character deletion).
.PP
If you would like to fully specify each window's termcap entry, you should
instead set the $SCREENCAP variable prior to running
.IR screen .
See the discussion on the \*QVIRTUAL TERMINAL\*U in this manual, and the termcap(5)
man page for more information on termcap definitions.
.sp
.ne 3
.B time
.PP
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 \*Qinfo\*U.
.sp
.ne 3
.BR "title " [ \fIwindowalias ]
.PP
Set the name of the current window to \fIwindowalias\fP. If no name is
specified,
.I screen
prompts for one. This command was known as `aka' in previous
releases.
.sp
.ne 3
.BI "unsetenv " var
.PP
Unset an environment variable.
.sp
.ne 3
.BR "vbell on" | off
.PP
If your terminal does not support
a visual bell, a `vbell-message' is displayed in the status line.
Sets the visual bell setting for this window. If your terminal does not support
a visual bell, a `vbell-message' is displayed in the status line.
Refer to the termcap variable `vb' (terminfo: 'flash').
.sp
.ne 3
.BI "vbell_msg " message
.PP
Sets the visual bell message. \fImessage\fP is printed to the status line if
the window receives a bell character (^G) and vbell is set to \*Qon\*U.
The default message is \*QWuff, Wuff!!\*U.
.sp
.ne 3
.BI "vbellwait " sec
.PP
Define a delay in seconds after each display of
.IR screen 's
visual bell message. The default is 1 second.
.sp
.ne 3
.B version
.PP
Print the current version and the compile date in the status line.
.sp
.ne 3
.BI "wall " "message"
.PP
Write a message to all displays. The message will appear in the terminal's
status line.
.sp
.ne 3
.BR "width " [ \fInum ]
.PP
Toggle the window width between 80 and 132 columns or set it to \fInum\fP
columns if an argument is specified.
This requires a capable terminal and the termcap entries \*QZ0\*U and \*QZ1\*U.
See the \*Qtermcap\*U command for more information.
.sp
.ne 3
.B windows
.PP
Uses the message line to display a list of all the windows.
Each window is listed by number with the name of process that has been
started 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 \*Qlogged in\*U are marked with a `$';
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 `@';
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 terminal's status line only the
portion around the current window is displayed.
.sp
.ne 3
.BR "wrap " [ on | off ]
.PP
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'.
.sp
.ne 3
.B writebuf
.PP
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
.I screen
users on the same host. The filename can be set with the \fIbufferfile\fP
command and defaults to \*Q/tmp/screen-exchange\*U.
.sp
.ne 3
.BR "writelock " [ on | "off\fR|\fBauto\fR]"
.PP
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 \*Qwritelock off\*U. If the user issues the command
\*Qwritelock on\*U he keeps the exclusive write permission while switching
to other windows.
.sp
.ne 3
.B xoff
.br
.B xon
.PP
Insert a CTRL-s / CTRL-q character to the stdin queue of the
current window.
.sp
.ne 3
.BR "zombie " [\fIkeys\fP]
.br
.BR "defzombie " [\fIkeys\fP]
.PP
Per default
.I screen
windows are removed from the window list as soon as
the windows process (e.g. shell) exits. When a string of two keys is 
specified to the zombie command, `dead' windows will remain in the list.
The \fBkill\fP kommand may be used to remove such a window. Pressing the 
first key in the dead window has the same effect. When pressing the second
key, screen will attempt to resurrect the window. The process that was
initially running in the window will be launched again. Calling \fBzombie\fP 
without parameters will clear the zombie setting, thus making windows disappear 
when their process exits.

As the zombie-setting is manipulated globally for all windows, this command 
should only be called \fBdefzombie\fP. Until we need this as a per window 
setting, the commands \fBzombie\fP and \fBdefzombie\fP are synonymous.

.SH "THE MESSAGE LINE"
.I Screen
displays informational messages and other diagnostics in a \fImessage line\fP.
While this line is distributed to appear at the bottom of the screen,
it can be defined to appear at the top of the screen during compilation.
If your terminal has a status line defined in its termcap,
.I screen
will use this for displaying its messages, otherwise a line of the
current 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.
.PP
The message line facility can be used by an application running in
the current window by means of the ANSI \fIPrivacy message\fP
control sequence.
For instance, from within the shell, try something like:
.IP
echo '<esc>^Hello world from window '$WINDOW'<esc>\e\e'
.PP
where '<esc>' is an \fIescape\fP, '^' is a literal up-arrow,
and '\e\e' turns into a single backslash.


.SH "FLOW-CONTROL"
Each window has a flow-control setting that determines how
.I screen
deals with
the XON and XOFF characters (and perhaps the interrupt character).
When flow-control is turned off,
.I 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 \fIemacs\fP editor, for instance).
The trade-off is that it will take longer for output from a \*Qnormal\*U
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
.I screen
commands (typically \*QC-a q\*U (xon)
and \*QC-a s\*U (xoff)).
The xon/xoff commands are also useful for typing C-s and C-q past a terminal
that intercepts these characters.
.PP
Each window has an initial flow-control value set with either the
.B \-f
option or the \*Qdefflow\*U .screenrc command. Per 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 \*Qflow\*U command bound to "C-a f".
.PP
The automatic flow-switching mode deals with
flow control using the TIOCPKT mode (like \*Qrlogin\*U does). If
the tty driver does not support TIOCPKT,
.I screen
tries to find out
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.
.PP
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
.I screen
with the \*Qinterrupt\*U
option (add the \*Qinterrupt\*U flag to the \*Qflow\*U command in
your .screenrc, or use the
.B \-i
command-line option).
This causes the output that
.I 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 \*QC-a l\*U you would see the version of the output you would
have gotten without \*Qinterrupt\*U 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 it is possible to interrupt
the output of the virtual terminal to your physical terminal when flow-control
is enabled.
If this happens, a simple refresh of the screen with \*QC-a l\*U will
restore it.
Give each mode a try, and use whichever mode you find more comfortable.


.SH "TITLES (naming windows)"
You can customize each window's name in the window display (viewed with the
\*Qwindows\*U command (C-a w)) 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.
.PP
The default name for all shell windows can be set with the \*Qshelltitle\*U
command in the .screenrc file, while all other windows are created with
a \*Qscreen\*U command and thus can have their name set with the
.B \-t
option.
Interactively, there is the title-string escape-sequence
(<esc>k\fIname\fP<esc>\e) and the \*Qtitle\*U 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 pre-defined names to keys with the \*Qtitle\*U command
to set things quickly without prompting.
.PP
Finally,
.I screen
has a shell-specific heuristic that is enabled by setting the window's name
to \*Q\fIsearch|name\fP\*U and arranging to have a null title escape-sequence
output as a part of your prompt.
The \fIsearch\fP portion specifies an end-of-prompt search string, while
the \fIname\fP portion specifies the default shell name for the window.
If the \fIname\fP ends in a `:'
.I screen
will add what it believes to be the current command running in the window
to the end of the window's shell name (e.\|g. \*Q\fIname:cmd\fP\*U).
Otherwise the current command name supersedes the shell name while it is
running.
.PP
Here's how it works:  you must modify your shell prompt to output a null
title-escape-sequence (<esc>k<esc>\e) as a part of your prompt.
The last part of your prompt must be the same as the string you specified
for the \fIsearch\fP portion of the title.
Once this is set up,
.I 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 either '!', '%', or '^'
.I screen
will use the first word on the following line (if found) in preference to
the just-found name.
This helps csh users get better command names when using job control or
history recall commands.
.PP
Here's some .screenrc examples:
.IP
screen -t top 2 nice top
.PP
Adding this line to your .screenrc would start a nice-d version of the
\*Qtop\*U command in window 2 named \*Qtop\*U rather than \*Qnice\*U.
.sp
.nf
	shelltitle '> |csh'
	screen 1
.fi
.sp
These commands would start a shell with 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:
.IP
/usr/joe/src/dir> trn
.PP
(it looks after the '> ' for the command name).
The window status would show the name \*Qtrn\*U while the command was
running, and revert to \*Qcsh\*U upon completion.
.IP
bind R screen -t '% |root:' su
.PP
Having this command in your .screenrc would bind the key
sequence \*QC-a R\*U to the \*Qsu\*U command and give it an
auto-title name of \*Qroot:\*U.
For this auto-title to work, the screen could look something
like this:
.sp
.nf
	% !em
	emacs file.c
.fi
.sp
Here the user typed the csh history command \*Q!em\*U which ran the
previously entered \*Qemacs\*U command.
The window status would show \*Qroot:emacs\*U during the execution
of the command, and revert to simply \*Qroot:\*U at its completion.
.PP
.nf
	bind o title
	bind E title ""
	bind u title (unknown)
.fi
.sp
The first binding doesn't have any arguments, so it would prompt you
for a title. when you type \*QC-a o\*U.
The second binding would clear an auto-title's current setting (C-a E).
The third binding would set the current window's title to \*Q(unknown)\*U
(C-a u).
.PP
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:
.IP
set prompt='^[[0000m^[k^[\e% '
.PP
The escape-sequence \*Q<esc>[0000m\*U not only normalizes the character
attributes, but all the zeros round the length of the invisible characters
up to 8.
Bash users will probably want to echo the escape sequence in the
PROMPT_COMMAND:
.IP
PROMPT_COMMAND='echo -n -e "\e033k\e033\e134"'
.PP
(I used \*Q\134\*U to output a `\e' because of a bug in bash v1.04).


.SH "THE VIRTUAL TERMINAL"
Each window in a 
.I screen
session emulates a VT100 terminal, with some extra functions added. The
VT100 emulator is hardcoded, no other terminal types can be emulated.
.br
Usually
.I 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
.I screen
has to tell the applications that some of the features
are missing. This is no problem on machines using termcap,
because
.I screen
can use the $TERMCAP variable to
customize the standard
.I screen
termcap.
.PP
But if you do a
rlogin on another machine or your machine supports only
terminfo this method fails. Because of this,
.I screen
offers a way to deal with these cases.
Here is how it works:
.PP
When
.I screen
tries to figure out a terminal name for itself,
it first looks
for an entry named \*Qscreen.<term>\*U, where <term> is
the contents of your $TERM variable.
If no such entry exists,
.I screen
tries \*Qscreen\*U (or \*Qscreen-w\*U if the terminal is wide
(132 cols or more)).
If even this entry cannot be found, \*Qvt100\*U is used as a
substitute.
.PP
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
.I screen
(named \*Qscreen.<dumbterm>\*U) 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.
.I Screen
also sets the $TERMCAP variable reflecting the capabilities
of the virtual terminal emulated. Notice that, however, on machines
using the terminfo database this variable has no effect.
Furthermore, the variable $WINDOW is set to the window number
of each window.
.PP
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,
.I 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
.IR screen ;
namely scrolling, clear screen, and direct cursor addressing
(in addition,
.I screen
does not run on hardcopy terminals or on terminals that over-strike).
.PP
Also, you can customize the $TERMCAP value used by
.I screen
by using the \*Qtermcap\*U .screenrc command, or
by defining the variable $SCREENCAP prior to startup.
When the is 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 \*Qscreen\*U (and/or \*Qscreen-w\*U) is defined.
.PP
Note that
.I screen
honors the \*Qterminfo\*U .screenrc command if the system uses the
terminfo database rather than termcap.
.PP
When the boolean `G0' capability is present in the termcap entry
for the terminal on which
.I screen
has been called, the terminal emulation of
.I 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:
\fIlock shift G0\fP (\fISI\fP), \fIlock shift G1\fP (\fISO\fP),
\fIlock shift G2\fP, \fIlock shift G3\fP, \fIsingle shift G2\fP,
and \fIsingle shift G3\fP.
When a virtual terminal is created or reset, the ASCII character
set is designated as \fIG0\fP through \fIG3\fP.
When the `G0' capability is present,
.I 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 \fISI\fP.
`E0' is the corresponding replacement for \fISO\fP. `C0' gives a character
by character translation string that is used during semi-graphics mode. This
string is built like the `acsc' terminfo capability.
.PP
When the `po' and `pf' capabilities are present in the terminal's
termcap entry, applications running in a
.I 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.
.PP
.I Screen
maintains a hardstatus line for every window. If a window
gets selected, the display's hardstatus will be updated to match
the window's hardstatus line. If the display has no hardstatus
the line will be displayed as a standard screen message.
The hardstatus line can be changed with the ANSI Application
Program Command (APC): \*QESC_<string>ESC\e\*U. As a convenience
for xterm users the sequence \*QESC]0..2;<string>^G\*U is
also accepted.
.PP
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.
.PP
The following is a list of control sequences recognized by
.IR screen .
\*Q(V)\*U and \*Q(A)\*U indicate VT100-specific and ANSI- or
ISO-specific functions, respectively.
.PP
.ta 22n
.TP 27
.B "ESC E"
Next Line
.TP 27
.B "ESC D"
Index
.TP 27
.B "ESC M"
Reverse Index
.TP 27
.B "ESC H"
Horizontal Tab Set
.TP 27
.B "ESC Z"
Send VT100 Identification String
.TP 27
.BR "ESC 7" "	(V)"
Save Cursor and Attributes
.TP 27
.BR "ESC 8" "	(V)"
Restore Cursor and Attributes
.TP 27
.BR "ESC [s" "	(A)"
Save Cursor and Attributes
.TP 27
.BR "ESC [u" "	(A)"
Restore Cursor and Attributes
.TP 27
.B "ESC c"
Reset to Initial State
.TP 27
.B "ESC g"
Visual Bell
.TP 27
.B "ESC \fPPn\fB p"
Cursor Visibility (97801)
.TP 27
\h'\w'ESC 'u'Pn = \fB6\fP
Invisible
.TP 27
\h'\w'ESC Pn = 'u'\fB7\fP
Visible
.TP 27
.BR "ESC =" "	(V)"
Application Keypad Mode
.TP 27
.BR "ESC >" "	(V)"
Numeric Keypad Mode
.TP 27
.BR "ESC # 8" "	(V)"
Fill Screen with E's
.TP 27
.BR "ESC \e" "	(A)"
String Terminator
.TP 27
.BR "ESC ^" "	(A)"
Privacy Message String (Message Line)
.TP 27
.B "ESC !"
Global Message String (Message Line)
.TP 27
.B "ESC k"
A.\|k.\|a. Definition String
.TP 27
.BR "ESC P" "	(A)"
Device Control String.
Outputs a string directly to the host
terminal without interpretation.
.TP 27
.BR "ESC _" "	(A)"
Application Program Command (Hardstatus)
.TP 27
.BR "ESC ]" "	(A)"
Operating System Command (Hardstatus, xterm title hack)
.TP 27
.BR "Control-N" "	(A)"
Lock Shift G1 (SO)
.TP 27
.BR "Control-O" "	(A)"
Lock Shift G0 (SI)
.TP 27
.BR "ESC n" "	(A)"
Lock Shift G2
.TP 27
.BR "ESC o" "	(A)"
Lock Shift G3
.TP 27
.BR "ESC N" "	(A)"
Single Shift G2
.TP 27
.BR "ESC O" "	(A)"
Single Shift G3
.TP 27
.BR "ESC ( \fPPcs" "	(A)"
Designate character set as G0
.TP 27
.BR "ESC ) \fPPcs" "	(A)"
Designate character set as G1
.TP 27
.BR "ESC * \fPPcs" "	(A)"
Designate character set as G2
.TP 27
.BR "ESC + \fPPcs" "	(A)"
Designate character set as G3
.TP 27
.B "ESC [ \fPPn\fB ; \fPPn\fB H"
Direct Cursor Addressing
.TP 27
.B "ESC [ \fPPn\fB ; \fPPn\fB f"
Direct Cursor Addressing
.TP 27
.B "ESC [ \fPPn\fB J"
Erase in Display
.TP 27
\h'\w'ESC [ 'u'Pn = None or \fB0\fP
From Cursor to End of Screen
.TP 27
\h'\w'ESC [ Pn = 'u'\fB1\fP
From Beginning of Screen to Cursor
.TP 27
\h'\w'ESC [ Pn = 'u'\fB2\fP
Entire Screen
.TP 27
.B "ESC [ \fPPn\fB K"
Erase in Line
.TP 27
\h'\w'ESC [ 'u'Pn = None or \fB0\fP
From Cursor to End of Line
.TP 27
\h'\w'ESC [ Pn = 'u'\fB1\fP
From Beginning of Line to Cursor
.TP 27
\h'\w'ESC [ Pn = 'u'\fB2\fP
Entire Line
.TP 27
.B "ESC [ \fPPn\fB A"
Cursor Up
.TP 27
.B "ESC [ \fPPn\fB B"
Cursor Down
.TP 27
.B "ESC [ \fPPn\fB C"
Cursor Right
.TP 27
.B "ESC [ \fPPn\fB D"
Cursor Left
.TP 27
.B "ESC [ \fPPs\fB ;\fP...\fB; \fPPs\fB m"
Select Graphic Rendition
.TP 27
\h'\w'ESC [ 'u'Ps = None or \fB0\fP
Default Rendition
.TP 27
\h'\w'ESC [ Ps = 'u'\fB1\fP
Bold
.TP 27
\h'\w'ESC [ Ps = 'u'\fB2\fP	(A)
Faint
.TP 27
\h'\w'ESC [ Ps = 'u'\fB3\fP	(A)
\fIStandout\fP Mode (ANSI: Italicized)
.TP 27
\h'\w'ESC [ Ps = 'u'\fB4\fP
Underlined
.TP 27
\h'\w'ESC [ Ps = 'u'\fB5\fP
Blinking
.TP 27
\h'\w'ESC [ Ps = 'u'\fB7\fP
Negative Image
.TP 27
\h'\w'ESC [ Ps = 'u'\fB22\fP	(A)
Normal Intensity
.TP 27
\h'\w'ESC [ Ps = 'u'\fB23\fP	(A)
\fIStandout\fP Mode off (ANSI: Italicized off)
.TP 27
\h'\w'ESC [ Ps = 'u'\fB24\fP	(A)
Not Underlined
.TP 27
\h'\w'ESC [ Ps = 'u'\fB25\fP	(A)
Not Blinking
.TP 27
\h'\w'ESC [ Ps = 'u'\fB27\fP	(A)
Positive Image
.TP 27
\h'\w'ESC [ Ps = 'u'\fB30\fP	(A)
Foreground Black
.TP 27
\h'\w'ESC [ Ps = 'u'\fB31\fP	(A)
Foreground Red
.TP 27
\h'\w'ESC [ Ps = 'u'\fB32\fP	(A)
Foreground Green
.TP 27
\h'\w'ESC [ Ps = 'u'\fB33\fP	(A)
Foreground Yellow
.TP 27
\h'\w'ESC [ Ps = 'u'\fB34\fP	(A)
Foreground Blue
.TP 27
\h'\w'ESC [ Ps = 'u'\fB35\fP	(A)
Foreground Magenta
.TP 27
\h'\w'ESC [ Ps = 'u'\fB36\fP	(A)
Foreground Cyan
.TP 27
\h'\w'ESC [ Ps = 'u'\fB37\fP	(A)
Foreground White
.TP 27
\h'\w'ESC [ Ps = 'u'\fB39\fP	(A)
Foreground Default
.TP 27
\h'\w'ESC [ Ps = 'u'\fB40\fP	(A)
Background Black
.TP 27
\h'\w'ESC [ Ps = 'u'\fB...\fP
...
.TP 27
\h'\w'ESC [ Ps = 'u'\fB49\fP	(A)
Background Default
.TP 27
.B "ESC [ \fPPn\fB g"
Tab Clear
.TP 27
\h'\w'ESC [ 'u'Pn = None or \fB0\fP
Clear Tab at Current Position
.TP 27
\h'\w'ESC [ Ps = 'u'\fB3\fP
Clear All Tabs
.TP 27
.BR "ESC [ \fPPn\fB ; \fPPn\fB r" "	(V)"
Set Scrolling Region
.TP 27
.BR "ESC [ \fPPn\fB I" "	(A)"
Horizontal Tab
.TP 27
.BR "ESC [ \fPPn\fB Z" "	(A)"
Backward Tab
.TP 27
.BR "ESC [ \fPPn\fB L" "	(A)"
Insert Line
.TP 27
.BR "ESC [ \fPPn\fB M" "	(A)"
Delete Line
.TP 27
.BR "ESC [ \fPPn\fB @" "	(A)"
Insert Character
.TP 27
.BR "ESC [ \fPPn\fB P" "	(A)"
Delete Character
.TP 27
.B "ESC [ \fPPn\fB S"
Scroll Scrolling Region Up
.TP 27
.B "ESC [ \fPPn\fB T"
Scroll Scrolling Region Down
.TP 27
.B "ESC [ \fPPs\fB ;\fP...\fB; \fPPs\fB h"
Set Mode
.TP 27
.B "ESC [ \fPPs\fB ;\fP...\fB; \fPPs\fB l"
Reset Mode
.TP 27
\h'\w'ESC [ 'u'Ps = \fB4\fP	(A)
Insert Mode
.TP 27
\h'\w'ESC [ Ps = 'u'\fB20\fP	(A)
\fIAutomatic Linefeed\fP Mode
.TP 27
\h'\w'ESC [ Ps = 'u'\fB34\fP
Normal Cursor Visibility
.TP 27
\h'\w'ESC [ Ps = 'u'\fB?1\fP	(V)
Application Cursor Keys
.TP 27
\h'\w'ESC [ Ps = 'u'\fB?3\fP	(V)
Change Terminal Width to 132 columns
.TP 27
\h'\w'ESC [ Ps = 'u'\fB?5\fP	(V)
Reverse Video
.TP 27
\h'\w'ESC [ Ps = 'u'\fB?6\fP	(V)
\fIOrigin\fP Mode
.TP 27
\h'\w'ESC [ Ps = 'u'\fB?7\fP	(V)
\fIWrap\fP Mode
.TP 27
\h'\w'ESC [ Ps = 'u'\fB?25\fP	(V)
Visible Cursor
.TP 27
.BR "ESC [ 5 i" "	(A)"
Start relay to printer (ANSI Media Copy)
.TP 27
.BR "ESC [ 4 i" "	(A)"
Stop relay to printer (ANSI Media Copy)
.TP 27
.B "ESC [ 8 ; \fPPh\fB ; \fPPw\fB t"
Resize the window to `Ph' lines and `Pw' columns (SunView special)
.TP 27
.B "ESC [ c"
Send VT100 Identification String
.TP 27
.B "ESC [ x"
Send Terminal Parameter Report
.TP 27
.B "ESC [ > c"
Send VT220 Secondary Device Attributes String
.TP 27
.B "ESC [ 6 n"
Send Cursor Position Report


.SH "INPUT TRANSLATION"
In order to do a full VT100 emulation \fIscreen\fP has to detect
that a sequence of characters in the input stream was generated
by a keypress on the user's keyboard and insert the VT100
style escape sequence. \fIScreen\fP has a very flexible way of doing
this by making it posible to map arbitrary commands on arbitrary
sequences of characters. For standard VT100 emulation the command
will always insert a string in the input buffer of the window
(see also command \fBstuff\fP in the command table).
Because the sequences generated by a keypress can
change after a reattach from a different terminal type, it is
possible to bind commands to the termcap name of the keys.
\fIScreen\fP will insert the correct binding after each
reattach. See the \fBbindkey\fP command for further details on the
syntax and examples.
.PP
Here is the table of the default key bindings. (A) means that the
command is executed if the keyboard is switched into application
mode.
.PP
.ta 18n 34n 50n
.nf
Key name	Termcap name	Command
\l'54n'
.ta 22n 34n 50n
Cursor up	ku	stuff \e033[A
		stuff \e033OA	(A)
Cursor down	kd	stuff \e033[B
		stuff \e033OB	(A)
Cursor right	kr	stuff \e033[C
		stuff \e033OC	(A)
Cursor left	kl	stuff \e033[D
		stuff \e033OD	(A)
Function key 0	k0	stuff \e033[10~
Function key 1	k1	stuff \e033OP
Function key 2	k2	stuff \e033OQ
Function key 3	k3	stuff \e033OR
Function key 4	k4	stuff \e033OS
Function key 5	k5	stuff \e033[15~
Function key 6	k6	stuff \e033[17~
Function key 7	k7	stuff \e033[18~
Function key 8	k8	stuff \e033[19~
Function key 9	k9	stuff \e033[20~
Function key 10	k;	stuff \e033[21~
Function key 11	F1	stuff \e033[22~
Function key 12	F2	stuff \e033[23~
Backspace	kb	stuff \e010
Home	kh	stuff \e033[1~
End	kH	stuff \e033[4~
Insert	kI	stuff \e033[2~
Delete	kD	stuff \e033[3~
Page up	kP	stuff \e033[5~
Page down	kN	stuff \e033[6~
Keypad 0	f0	stuff 0
		stuff \e033Op	(A)
Keypad 1	f1	stuff 1
		stuff \e033Oq	(A)
Keypad 2	f2	stuff 2
		stuff \e033Or	(A)
Keypad 3	f3	stuff 3
		stuff \e033Os	(A)
Keypad 4	f4	stuff 4
		stuff \e033Ot	(A)
Keypad 5	f5	stuff 5
		stuff \e033Ou	(A)
Keypad 6	f6	stuff 6
		stuff \e033Ov	(A)
Keypad 7	f7	stuff 7
		stuff \e033Ow	(A)
Keypad 8	f8	stuff 8
		stuff \e033Ox	(A)
Keypad 9	f9	stuff 9
		stuff \e033Oy	(A)
Keypad +	f+	stuff +
		stuff \e033Ok	(A)
Keypad -	f-	stuff -
		stuff \e033Om	(A)
Keypad *	f*	stuff *
		stuff \e033Oj	(A)
Keypad /	f/	stuff /
		stuff \e033Oo	(A)
Keypad =	fq	stuff =
		stuff \e033OX	(A)
Keypad .	f.	stuff .
		stuff \e033On	(A)
Keypad ,	f,	stuff ,
		stuff \e033Ol	(A)
Keypad enter	fe	stuff \e015
		stuff \e033OM	(A)
.fi


.SH SPECIAL TERMINAL CAPABILITIES
The following table describes all terminal capabilities
that are recognized by \fIscreen\fP and are not in the
termcap(5) manual.
You can place these capabilities in your termcap entries (in
`/etc/termcap') or use them with the commands `termcap', `terminfo' and
`termcapinfo' in your screenrc files. It is often not possible to place
these capabilities in the terminfo database.
.PP
.ta 5n
.TP 13
.BI LP "	(bool)"
Terminal has VT100 style margins (`magic margins'). Note that
this capability is obsolete because \fIscreen\fP uses the standard 'xn'
instead.
.TP 13
.BI Z0 "	(str)"
Change width to 132 columns.
.TP 13
.BI Z1 "	(str)"
Change width to 80 columns.
.TP 13
.BI WS "	(str)"
Resize display. This capability has the desired width and height as
arguments. \fISunView(tm)\fP example: '\eE[8;%d;%dt'.
.TP 13
.BI 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 'nx'.
.TP 13
.BI G0 "	(bool)"
Terminal can deal with ISO 2022 font selection sequences.
.TP 13
.BI S0 "	(str)"
Switch charset 'G0' to the specified charset. Default
is '\eE(%.'.
.TP 13
.BI E0 "	(str)"
Switch charset 'G0' back to standard charset. Default
is '\eE(B'.
.TP 13
.BI C0 "	(str)"
Use the string as a conversion table for font '0'. See
the 'ac' capability for more details.
.TP 13
.BI CS "	(str)"
Switch cursorkeys to application mode.
.TP 13
.BI CE "	(str)"
Switch cursorkeys back to normal mode.
.TP 13
.BI AN "	(bool)"
Turn on autonuke. See the 'autonuke' command for more details.
.TP 13
.BI OL "	(num)"
Set the output buffer limit. See the 'obuflimit' command for more details.
.TP 13
.BI KJ "	(str)"
Set the kanji type of the terminal. Valid strings are \*Qjis\*U,
\*Qeuc\*U and \*Qsjis\*U.
.TP 13
.BI AF "	(str)"
Change character forground color in an ANSI conform way. This
capability will almost always be set to '\eE[3%dm' ('\eE[3%p1%dm'
on terminfo machines).
.TP 13
.BI AB "	(str)"
Same as 'AF', but change background color.
.TP 13
.BI AX "	(bool)"
Does understand ANSI set default fg/bg color (\eE[39m / \eE[49m).
.TP 13
.BI XC "	(str)"
Describe a translation of characters to strings depending on the
current font. More details follow in the next section.

.SH CHARACTER TRANSLATION
\fIScreen\fP has a powerful mechanism to translate characters to arbitrary
strings depending on the current font and terminal type.
Use this feature if you want to work with a common standard character
set (say ISO8851-latin1) even on terminals that scatter the more
unusual characters over several national language font pages.

Syntax:
.nf
    \fBXC=\fP\fI<charset-mapping>\fP{\fB,,\fP\fI<charset-mapping>\fP}
    \fI<charset-mapping>\fP := \fI<designator><template>\fP{\fB,\fP\fI<mapping>\fP}
    \fI<mapping>\fP := \fI<char-to-be-mapped><template-arg>\fP
.fi

The things in braces may be repeated any number of times.

A \fI<charset-mapping>\fP tells \fIscreen\fP how to map characters
in font \fI<designator>\fP ('B': Ascii, 'A': UK, 'K': german, etc.)
to strings. Every \fI<mapping>\fP describes to what string a single
character will be translated. A template mechanism is used, as 
most of the time the codes have a lot in common (for example
strings to switch to and from another charset). Each occurence
of '%' in \fI<template>\fP gets substituted with the \fI<template-arg>\fP
specified together with the character. If your strings are not
similar at all, then use '%' as a template and place the full
string in \fI<template-arg>\fP. A quoting mechanism was added to make
it possible to use a real '%'. The '\e' character quotes the
special characters '\e', '%', and ','.

Here is an example:

    termcap hp700 'XC=B\eE(K%\eE(B,\e304[,\e326\e\e\e\e,\e334]'

This tells \fIscreen\fP, how to translate ISOlatin1 (charset 'B')
upper case umlaut characters on a hp700 terminal that has a
german charset. '\e304' gets translated to '\eE(K[\eE(B' and so on.
Note that this line gets parsed *three* times before the internal
lookup table is built, therefore a lot of quoting is needed to
create a single '\e'.

Another extension was added to allow more emulation: If a mapping
translates the unquoted '%' char, it will be sent to the terminal
whenever \fIscreen\fP switches to the corresponding \fI<designator>\fP. In this
special case the template is assumed to be just '%' because
the charset switch sequence and the character mappings normaly
haven't much in common.

This example shows one use of the extension:

    termcap xterm 'XC=K%,%\eE(B,[\e304,\e\e\e\e\e326,]\e334'

Here, a part of the german ('K') charset is emulated on an xterm.
If \fIscreen\fP has to change to the 'K' charset, '\eE(B' will be sent
to the terminal, i.e. the ASCII charset is used instead. The
template is just '%', so the mapping is straightforward: '['
to '\e304', '\e' to '\e326', and ']' to '\e334'.

.SH ENVIRONMENT
.PD 0
.IP COLUMNS 15
Number of columns on the terminal (overrides termcap entry).
.IP HOME
Directory in which to look for .screenrc.
.IP ISCREENRC
Alternate user screenrc file.
.IP LINES
Number of lines on the terminal (overrides termcap entry).
.IP LOCKPRG
Screen lock program.
.IP NETHACKOPTIONS
Turns on nethack option.
.IP PATH
Used for locating programs to run.
.IP SCREENCAP
For customizing a terminal's TERMCAP value.
.IP SCREENDIR
Alternate socket directory.
.IP SCREENRC
Alternate user screenrc file.
.IP SHELL
Default shell program for opening windows (default \*Q/bin/sh\*U).
.IP STY
Alternate socket name.
.IP SYSSCREENRC
Alternate system screenrc file.
.IP TERM
Terminal name.
.IP TERMCAP
Terminal description.


.SH FILES
.PD 0
.IP $SYSSCREENRC 28
.IP /local/etc/screenrc
\fIscreen\fP initialization commands
.IP $ISCREENRC
.IP $SCREENRC
.IP $HOME/.iscreenrc
.IP $HOME/.screenrc
Read in after /local/etc/screenrc
.IP $ISCREENDIR/S-<login>
.IP $SCREENDIR/S-<login>
.IP /local/screens/S-<login>
Socket directories (default)
.IP /usr/tmp/screens/S-<login>
Alternate socket directories.
.IP "<socket directory>/.termcap"
Written by the "termcap" output function
.IP /usr/tmp/screens/screen-exchange
or
.IP /tmp/screen-exchange
\fIscreen\fP `interprocess communication buffer'
.IP hardcopy.[0-9]
Screen images created by the hardcopy function
.IP screenlog.[0-9]
Output log files created by the log function
.IP /usr/lib/terminfo/?/*
or
.IP /etc/termcap
Terminal capability databases
.IP /etc/utmp
Login records
.IP $LOCKPRG
Program that locks a terminal.


.SH "SEE ALSO"
termcap(5), utmp(5), vi(1), captoinfo(1), tic(1)


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

.SH COPYLEFT
.nf
Copyright (C) 1993
	Juergen Weigert (jnweiger@immd4.informatik.uni-erlangen.de)
	Michael Schroeder (mlschroe@immd4.informatik.uni-erlangen.de)
Copyright (C) 1987 Oliver Laumann
.fi
.PP
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
.PP
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
.PP
You should have received a copy of the GNU General Public License
along with this program (see the file COPYING); if not, write to the
Free Software Foundation, Inc.,
59 Temple Place - Suite 330, Boston, MA  02111-1307, USA

.SH CONTRIBUTORS
.nf
Ken Beal (kbeal@amber.ssd.csd.harris.com),
Rudolf Koenig (rfkoenig@immd4.informatik.uni-erlangen.de),
Toerless Eckert (eckert@immd4.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 (mrgreen@mame.mu.oz.au),
Christopher Williams (cgw@unt.edu),
Matt Mosley (mattm@access.digex.net),
Gregory Neil Shapiro (gshapiro@wpi.WPI.EDU).
.fi


.SH VERSION
This is version 3.7.0. 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.


.SH BUGS
.PD
.IP \(bu 3
`dm' (delete mode) and `xs' are not handled
correctly (they are ignored). `xn' is treated as a magic-margin
indicator.
.IP \(bu
.I Screen
has no clue about double-high or double-wide characters.
But this is the only area where
.I vttest
is allowed to fail.
.IP \(bu
It is not possible to change the environment variable $TERMCAP when
reattaching under a different terminal type.
.IP \(bu
The support of terminfo based systems is very limited. Adding extra
capabilities to $TERMCAP may not have any effects.
.IP \(bu
.I Screen
does not make use of hardware tabs.
.IP \(bu
.I Screen
must be installed as set-uid with owner 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 \*Q/etc/utmp\*U.
.IP \(bu
Entries in \*Q/etc/utmp\*U are not removed when
.I 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.
.IP \(bu
.I Screen
may give a strange warning when your tty has no utmp entry.
.IP \(bu
When the modem line was hung up,
.I screen
may not automatically detach (or quit)
unless the device driver is configured to send a HANGUP signal.
To detach a
.I screen
session use the -D or -d command line option.
.IP \(bu
A weird imagination is most useful to gain full advantage of all the features.
.IP \(bu
Send bugreports, fixes, enhancements, t-shirts, money, beer & pizza to
.BR screen@uni-erlangen.de .