screen - Online in the Cloud

PROGRAM:

NAME

screen - screen manager with VT100/ANSI terminal emulation

SYNOPSIS

screen [ -options ] [ cmd [ args ] ]
screen -r [[pid.]tty[.host]]
screen -r sessionowner/[[pid.]tty[.host]]

DESCRIPTION

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 ISO
6429 (ECMA 48, ANSI X3.64) 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.

When screen is called, it creates a single window with a shell in it (or the specified
command) and then gets out of your way so that you can use the program as you normally
would. Then, at any time, you can create new (full-screen) windows with other programs in
them (including more shells), kill 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. All windows run their programs
completely independent of each other. Programs continue to run when their window is
currently not visible and even when the whole screen session is detached from the user's
terminal. When a program terminates, screen (per default) kills the window that contained
it. If this window was in the foreground, the display switches to the previous window; if
none are left, screen exits. Shells usually distinguish between running as login-shell or
sub-shell. Screen runs them as sub-shells, unless told otherwise (See "shell" .screenrc
command).

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.

Screen does not understand the prefix "C-" to mean control, although this notation is used
in this manual for readability. Please use the caret notation ("^A" instead of "C-a") as
arguments to e.g. the escape command or the -e option. Screen will also print out control
characters in caret notation.

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

screen emacs prog.c

from a shell prompt within a previously created window. This will not run another copy of
screen, but will instead supply the command name and its arguments to the window manager
(specified in the $STY environment variable) who will use it to create the new window.
The above example would start the emacs editor (editing prog.c) and switch to its window.
- Note that you cannot transport environment variables from the invoking shell to the
application (emacs in this case), because it is forked from the parent screen process, not
from the invoking shell.

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

GETTING STARTED

Before you begin to use screen you'll need to make sure you have correctly selected your
terminal type, just as you would for any other termcap/terminfo program. (You can do this
by using tset for example.)

If you're impatient and want to get started without doing a lot more reading, you should
remember this one command: "C-a ?". Typing these two characters will display a list of
the available screen commands and their bindings. Each keystroke is discussed in the
section "DEFAULT KEY BINDINGS". The manual section "CUSTOMIZATION" deals with the contents
of your .screenrc.

If your terminal is a "true" auto-margin terminal (it doesn't allow the last position on
the screen to be updated without scrolling the screen) consider using a version of your
terminal's termcap that has automatic margins turned off. This will ensure an accurate and
optimal update of the screen in all circumstances. Most terminals nowadays have "magic"
margins (automatic margins plus usable last column). This is the VT100 style type and
perfectly suited for screen. If all you've got is a "true" auto-margin terminal screen
will be content to use it, but updating a character put into the last position on the
screen may not be possible until the screen scrolls or the character is moved into a safe
position in some other way. This delay can be shortened by using a terminal with insert-
character capability.

COMMAND-LINE OPTIONS

Screen has the following command-line options:

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

-A Adapt the sizes of all windows to the size of the current terminal. By default,
screen tries to restore its old window sizes when attaching to resizable terminals
(those with "WS" in its description, e.g. suncmd or some xterm).

-c file
override the default configuration file from "$HOME/.screenrc" to file.

-d|-D [pid.tty.host]
does not start screen, but detaches the elsewhere running screen session. It has the
same effect as typing "C-a d" from screen's controlling terminal. -D is the
equivalent to the power detach key. If no session can be detached, this option is
ignored. In combination with the -r/-R option more powerful effects can be achieved:

-d -r Reattach a session and if necessary detach it first.

-d -R Reattach a session and if necessary detach or even create it first.

-d -RR Reattach a session and if necessary detach or create it. Use the first session if
more than one session is available.

-D -r Reattach a session. If necessary detach and logout remotely first.

-D -R Attach here and now. In detail this means: If a session is running, then reattach.
If necessary detach and logout remotely first. If it was not running create it
and notify the user. This is the author's favorite.

-D -RR Attach here and now. Whatever that means, just do it.

Note: It is always a good idea to check the status of your sessions by means of
"screen -list".

-e xy
specifies the command character to be x and the character generating a literal
command character to y (when typed after the command character). The default is "C-
a" and `a', which can be specified as "-e^Aa". When creating a 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 "defescape" or "escape" respectively.

-f, -fn, and -fa
turns flow-control on, off, or "automatic switching mode". This can also be defined
through the "defflow" .screenrc command.

-h num
Specifies the history scrollback buffer to be num lines high.

-i will cause the interrupt key (usually C-c) to interrupt the display immediately when
flow-control is on. See the "defflow" .screenrc command for details. The use of
this option is discouraged.

-l and -ln
turns login mode on or off (for /var/run/utmp updating). This can also be defined
through the "deflogin" .screenrc command.

-ls [match]
-list [match]
does not start screen, but prints a list of pid.tty.host strings and creation
timestamps identifying your screen sessions. Sessions marked `detached' can be
resumed with "screen -r". Those marked `attached' are running and have a controlling
terminal. If the session runs in multiuser mode, it is marked `multi'. Sessions
marked as `unreachable' either live on a different host or are `dead'. An
unreachable session is considered dead, when its name matches either the name of the
local host, or the specified parameter, if any. See the -r flag for a description
how to construct matches. Sessions marked as `dead' should be thoroughly checked and
removed. Ask your system administrator if you are not sure. Remove sessions with the
-wipe option.

-L tells screen to turn on automatic output logging for the windows.

-m causes screen to ignore the $STY environment variable. With "screen -m" creation of a
new session is enforced, regardless whether screen is called from within another
screen session or not. This flag has a special meaning in connection with the `-d'
option:

-d -m Start screen in "detached" mode. This creates a new session but doesn't attach to
it. This is useful for system startup scripts.

-D -m This also starts screen in "detached" mode, but doesn't fork a new process. The
command exits if the session terminates.

-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 "termcap" command.

-p number_or_name|-|=|+
Preselect a window. This is useful when you want to reattach to a specific window or
you want to send a command via the "-X" option to a specific window. As with screen's
select command, "-" selects the blank window. As a special case for reattach, "="
brings up the windowlist on the blank window, while a "+" will create a new window.
The command will not be executed if the specified window could not be found.

-q Suppress printing of error messages. In combination with "-ls" the exit value is as
follows: 9 indicates a directory without sessions. 10 indicates a directory with
running but not attachable sessions. 11 (or more) indicates 1 (or more) usable
sessions. In combination with "-r" the exit value is as follows: 10 indicates that
there is no session to resume. 12 (or more) indicates that there are 2 (or more)
sessions to resume and you should specify which one to choose. In all other cases
"-q" has no effect.

-Q Some commands now can be queried from a remote session using this flag, e.g. "screen
-Q windows". The commands will send the response to the stdout of the querying
process. If there was an error in the command, then the querying process will exit
with a non-zero status.

The commands that can be queried now are:
echo
info
lastmsg
number
select
time
title
windows

-r [pid.tty.host]
-r sessionowner/[pid.tty.host]
resumes a detached screen session. No other options (except combinations with -d/-D)
may be specified, though an optional prefix of [pid.]tty.host may be needed to
distinguish between multiple detached screen sessions. The second form is used to
connect to another user's screen session which runs in multiuser mode. This indicates
that screen should look for sessions in another user's directory. This requires
setuid-root.

-R resumes screen only when it's unambiguous which one to attach, usually when only one
screen is detached. Otherwise lists available sessions. -RR attempts to resume the
youngest (in terms of creation time) detached 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 -R had not been
specified. The option is set by default if screen is run as a login-shell (actually
screen uses "-xRR" in that case). For combinations with the -d/-D option see there.
Note: Time-based session selection is a Debian addition.

-s program
sets the default shell to the program specified, instead of the value in the
environment variable $SHELL (or "/bin/sh" if not defined). This can also be defined
through the "shell" .screenrc command. See also there.

-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 "screen -list" and "screen -r"
actions. It substitutes the default [tty.host] suffix.

-t name
sets the title (a.k.a.) for the default shell or specified program. See also the
"shelltitle" .screenrc command.

-T term
Set the $TERM environment varible using the spcified term as opposed to the defualt
setting of screen.

-U Run screen in UTF-8 mode. This option tells screen that your terminal sends and
understands UTF-8 encoded characters. It also sets the default encoding for new
windows to `utf8'.

-v Print version number.

-wipe [match]
does the same as "screen -ls", but removes destroyed sessions instead of marking them
as `dead'. An unreachable session is considered dead, when its name matches either
the name of the local host, or the explicitly given parameter, if any. See the -r
flag for a description how to construct matches.

-x Attach to a not detached screen session. (Multi display mode). Screen refuses to
attach from within itself. But when cascading multiple screens, loops are not
detected; take care.

-X Send the specified command to a running screen session. You may use the -S option to
specify the screen session if you have several screen sessions running. You can use
the -d or -r option to tell screen to look only for attached or detached screen
sessions. Note that this command doesn't work if the session is password protected.

-4 Resolve hostnames only to IPv4 addresses.

-6 Resolve hostnames only to IPv6 addresses.

DEFAULT KEY BINDINGS

As mentioned, each screen command consists of a "C-a" followed by one other character.
For your convenience, all commands that are bound to lower-case letters are also bound to
their control character counterparts (with the exception of "C-a a"; see below), thus, "C-
a c" as well as "C-a C-c" can be used to create a window. See section "CUSTOMIZATION" for
a description of the command.

The following table shows the default key bindings:

C-a ' (select) Prompt for a window name or number to switch to.

C-a " (windowlist -b)
Present a list of all windows for selection.

C-a 0 (select 0)
… …
C-a 9 (select 9)
C-a - (select -) Switch to window number 0 - 9, or to the blank window.

C-a tab (focus) Switch the input focus to the next region. See also split,
remove, only.

C-a C-a (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 "-e]x", this
command becomes "]]".

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

C-a A (title) Allow the user to enter a name for the current window.

C-a b
C-a C-b (break) Send a break to window.

C-a B (pow_break) Reopen the terminal line and send a break.

C-a c
C-a C-c (screen) Create a new window with a shell and switch to that window.

C-a C (clear) Clear the screen.

C-a d
C-a C-d (detach) Detach screen from this terminal.

C-a D D (pow_detach) Detach and logout.

C-a f
C-a C-f (flow) Toggle flow on, off or auto.

C-a F (fit) Resize the window to the current region size.

C-a C-g (vbell) Toggles screen's visual bell mode.

C-a h (hardcopy) Write a hardcopy of the current window to the file "hardcopy.n".

C-a H (log) Begins/ends logging of the current window to the file
"screenlog.n".

C-a i
C-a C-i (info) Show info about this window.

C-a k
C-a C-k (kill) Destroy current window.

C-a l
C-a C-l (redisplay) Fully refresh current window.

C-a L (login) Toggle this windows login slot. Available only if screen is
configured to update the utmp database.

C-a m
C-a C-m (lastmsg) Repeat the last message displayed in the message line.

C-a M (monitor) Toggles monitoring of the current window.

C-a space
C-a n
C-a C-n (next) Switch to the next window.

C-a N (number) Show the number (and title) of the current window.

C-a backspace
C-a C-h
C-a p
C-a C-p (prev) Switch to the previous window (opposite of C-a n).

C-a q
C-a C-q (xon) Send a control-q to the current window.

C-a Q (only) Delete all regions but the current one. See also split, remove,
focus.

C-a r
C-a C-r (wrap) Toggle the current window's line-wrap setting (turn the current
window's automatic margins on and off).

C-a s
C-a C-s (xoff) Send a control-s to the current window.

C-a S (split) Split the current region horizontally into two new ones. See
also only, remove, focus.

C-a t
C-a C-t (time) Show system information.

C-a v (version) Display the version and compilation date.

C-a C-v (digraph) Enter digraph.

C-a w
C-a C-w (windows) Show a list of window.

C-a W (width) Toggle 80/132 columns.

C-a x
C-a C-x (lockscreen) Lock this terminal.

C-a X (remove) Kill the current region. See also split, only, focus.

C-a z
C-a C-z (suspend) Suspend screen. Your system must support BSD-style job-control.

C-a Z (reset) Reset the virtual terminal to its "power-on" values.

C-a . (dumptermcap) Write out a ".termcap" file.

C-a ? (help) Show key bindings.

C-a \ (quit) Kill all windows and terminate screen.

C-a : (colon) Enter command line mode.

C-a [
C-a C-[
C-a esc (copy) Enter copy/scrollback mode.

C-a C-]
C-a ] (paste .) Write the contents of the paste buffer to the stdin queue of the
current window.

C-a {
C-a } (history) Copy and paste a previous (command) line.

C-a > (writebuf) Write paste buffer to a file.

C-a < (readbuf) Reads the screen-exchange file into the paste buffer.

C-a = (removebuf) Removes the file used by C-a < and C-a >.

C-a , (license) Shows where screen comes from, where it went to and why you can
use it.

C-a _ (silence) Start/stop monitoring the current window for inactivity.

C-a | (split -v) Split the current region vertically into two new ones.

C-a * (displays) Show a listing of all currently attached displays.

CUSTOMIZATION

The "socket directory" defaults either to $HOME/.screen or simply to /tmp/screens or
preferably to /var/run/screen chosen at compile-time. If screen is installed setuid-root,
then the administrator should compile screen with an adequate (not NFS mounted) socket
directory. If screen is not running setuid-root, the user can specify any mode 700
directory in the environment variable $SCREENDIR.

When screen is invoked, it executes initialization commands from the files "/etc/screenrc"
and ".screenrc" in the user's home directory. These are the "programmer's defaults" that
can be overridden in the following ways: for the global screenrc file screen searches for
the environment variable $SYSSCREENRC (this override feature may be disabled at compile-
time). The user specific screenrc file is searched in $SCREENRC, then $HOME/.screenrc.
The command line option -c takes precedence over the above user screenrc files.

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 screen session.
Commands are listed one per line, with empty lines being ignored. A command's arguments
are separated by tabs or spaces, and may be surrounded by single or double quotes. A `#'
turns the rest of the line into a comment, except in quotes. Unintelligible lines are
warned about and ignored. Commands may contain references to environment variables. The
syntax is the shell-like "$VAR " or "${VAR}". Note that this causes incompatibility with
previous screen versions, as now the '$'-character has to be protected with '\' if no
variable substitution shall be performed. A string in single-quotes is also protected from
variable substitution.

Two configuration files are shipped as examples with your screen distribution:
"etc/screenrc" and "etc/etcscreenrc". They contain a number of useful examples for various
commands.

Customization can also be done 'on-line'. To enter the command mode type `C-a :'. Note
that commands starting with "def" change default values, while others change current
settings.

The following commands are available:

acladd usernames [crypted-pw]
addacl usernames

Enable users to fully access this screen session. Usernames can be one user or a comma
separated list of users. This command enables to attach to the screen session and performs
the equivalent of `aclchg usernames +rwx "#?"'. executed. To add a user with restricted
access, use the `aclchg' command below. If an optional second parameter is supplied, it
should be a crypted password for the named user(s). `Addacl' is a synonym to `acladd'.
Multi user mode only.

aclchg usernames permbits list
chacl usernames permbits list

Change permissions for a comma separated list of users. Permission bits are represented as
`r', `w' and `x'. Prefixing `+' grants the permission, `-' removes it. The third parameter
is a comma separated list of commands and/or windows (specified either by number or
title). The special list `#' refers to all windows, `?' to all commands. if usernames
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 username -w+w
2'. To allow read-only access to the session: `aclchg username -w "#"'. As soon as a
user's name is known to 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.
Rights of the special username nobody cannot be changed (see the "su" command). `Chacl'
is a synonym to `aclchg'. Multi user mode only.

acldel username

Remove a user from 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.

aclgrp username [groupname]

Creates groups of users that share common access rights. The name of the group is the
username of the group leader. Each member of the group inherits the permissions that are
granted to the group leader. That means, if a user fails an access check, another check is
made for the group leader. A user is removed from all groups the special value "none" is
used for groupname. If the second parameter is omitted all groups the user is in are
listed.

aclumask [[users]+bits |[users]-bits …. ]
umask [[users]+bits |[users]-bits …. ]

This specifies the access other users have to windows that will be created by the caller
of the command. Users may be no, one or a comma separated list of known usernames. If no
users are specified, a list of all currently known users is assumed. Bits is any
combination of access control bits allowed defined with the "aclchg" command. The special
username "?" predefines the access that not yet known users will be granted to any window
initially. The special username "??" predefines the access that not yet known users are
granted to any command. Rights of the special username nobody cannot be changed (see the
"su" command). `Umask' is a synonym to `aclumask'.

activity message

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

'Activity in window %n'

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

allpartial on|off

If set to on, only the current cursor line is refreshed on window change. This affects
all windows and is useful for slow terminal lines. The previous setting of full/partial
refresh for each window is restored with "allpartial off". This is a global flag that
immediately takes effect on all windows overriding the "partial" settings. It does not
change the default redraw behavior of newly created windows.

altscreen on|off

If set to on, "alternate screen" support is enabled in virtual terminals, just like in
xterm. Initial setting is `off'.

at [identifier][#|*|%] command [args … ]

Execute a command at other displays or windows as if it had been entered there. "At"
changes the context (the `current window' or `current display' setting) of the command. If
the first parameter describes a non-unique context, the command will be executed multiple
times. If the first parameter is of the form `identifier*' then identifier is matched
against user names. The command is executed once for each display of the selected
user(s). If the first parameter is of the form `identifier%' identifier is matched against
displays. Displays are named after the ttys they attach. The prefix `/dev/' or `/dev/tty'
may be omitted from the identifier. If identifier has a `#' or nothing appended it is
matched against window numbers and titles. Omitting an identifier in front of the `#', `*'
or `%'-character selects all users, displays or windows because a prefix-match is
performed. Note that on the affected display(s) a short message will describe what
happened. Permission is checked for initiator of the "at" command, not for the owners of
the affected display(s). Note that the '#' character works as a comment introducer when
it is preceded by whitespace. This can be escaped by prefixing a '\'. Permission is
checked for the initiator of the "at" command, not for the owners of the affected
display(s).
Caveat: When matching against windows, the command is executed at least once per window.
Commands that change the internal arrangement of windows (like "other") may be called
again. In shared windows the command will be repeated for each attached display. Beware,
when issuing toggle commands like "login"! Some commands (e.g. "process") require that a
display is associated with the target windows. These commands may not work correctly
under "at" looping over windows.

attrcolor attrib [attribute/color-modifier]

This command can be used to highlight attributes by changing the color of the text. If the
attribute attrib is in use, the specified attribute/color modifier is also applied. If no
modifier is given, the current one is deleted. See the "STRING ESCAPES" chapter for the
syntax of the modifier. Screen understands two pseudo-attributes, "i" stands for high-
intensity foreground color and "I" for high-intensity background color.

Examples:

attrcolor b "R"

Change the color to bright red if bold text is to be printed.

attrcolor u "-u b"

Use blue text instead of underline.

attrcolor b ".I"

Use bright colors for bold text. Most terminal emulators do this already.

attrcolor i "+b"

Make bright colored text also bold.

autodetach on|off

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

autonuke on|off

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

backtick id lifespan autorefresh cmd args…
backtick id

Program the backtick command with the numerical id id. The output of such a command is
used for substitution of the "%`" string escape. The specified lifespan is the number of
seconds the output is considered valid. After this time, the command is run again if a
corresponding string escape is encountered. The autorefresh parameter triggers an
automatic refresh for caption and hardstatus strings after the specified number of
seconds. Only the last line of output is used for substitution.
If both the lifespan and the autorefresh parameters are zero, the backtick program is
expected to stay in the background and generate output once in a while. In this case, the
command is executed right away and screen stores the last line of output. If a new line
gets printed screen will automatically refresh the hardstatus or the captions.
The second form of the command deletes the backtick command with the numerical id id.

bce [on|off]

Change background-color-erase setting. If "bce" is set to on, all characters cleared by an
erase/insert/scroll/clear operation will be displayed in the current background color.
Otherwise the default background color is used.

bell_msg [message]

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

'Bell in window %n'

An empty message can be supplied to the "bell_msg" command to suppress output of a message
line (bell_msg ""). Without parameter, the current message is shown.

bind [-c class] key [command [args]]

Bind a command to a key. By default, most of the commands provided by screen are bound to
one or more keys as indicated in the "DEFAULT KEY BINDINGS" section, e.g. the command to
create a new window is bound to "C-c" and "c". The "bind" command can be used to redefine
the key bindings and to define new bindings. The key argument is either a single
character, a two-character sequence of the form "^x" (meaning "C-x"), a backslash followed
by an octal number (specifying the ASCII code of the character), or a backslash followed
by a second character, such as "\^" or "\\". The argument can also be quoted, if you
like. If no further argument is given, any previously established binding for this key is
removed. The command argument can be any command listed in this section.

If a command class is specified via the "-c" option, the key is bound for the specified
class. Use the "command" command to activate a class. Command classes can be used to
create multiple command keys or multi-character bindings.

Some examples:

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

would bind the space key to the command that displays a list of windows (so that the
command usually invoked by "C-a C-w" would also be available as "C-a space"). The next
three lines remove the default kill binding from "C-a C-k" and "C-a k". "C-a K" is then
bound to the kill command. Then it binds "C-f" to the command "create a window with a
TELNET connection to foobar", and bind "escape" to the command that creates an non-login
window with a.k.a. "root" in slot #9, with a superuser shell and a scrollback buffer of
1000 lines.

bind -c demo1 0 select 10
bind -c demo1 1 select 11
bind -c demo1 2 select 12
bindkey "^B" command -c demo1

makes "C-b 0" select window 10, "C-b 1" window 11, etc.

bind -c demo2 0 select 10
bind -c demo2 1 select 11
bind -c demo2 2 select 12
bind - command -c demo2

makes "C-a - 0" select window 10, "C-a - 1" window 11, etc.

bindkey [-d] [-m] [-a] [[-k|-t] string [cmd args]]

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 "INPUT TRANSLATION" for a list of default key bindings.
If the -d option is given, bindkey modifies the default table, -m changes the copy mode
table and with neither option the user table is selected. The argument 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 -k option).
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 -a option.
The -t option tells screen not to do inter-character timing. One cannot turn off the
timing if a termcap capability is used.
Cmd can be any of screen's commands with an arbitrary number of args. If cmd is omitted
the key-binding is removed from the table.
Here are some examples of keyboard bindings:

bindkey -d
Show all of the default key bindings. The application mode entries are marked with [A].

bindkey -k k1 select 1
Make the "F1" key switch to window one.

bindkey -t foo stuff barfoo
Make "foo" an abbreviation of the word "barfoo". Timeout is disabled so that users can
type slowly.

bindkey "\024" mapdefault
This key-binding makes "^T" an escape character for key-bindings. If you did the above
"stuff barfoo" binding, you can enter the word "foo" by typing "^Tfoo". If you want to
insert a "^T" you have to press the key twice (i.e., escape the escape binding).

bindkey -k F1 command
Make the F11 (not F1!) key an alternative screen escape (besides ^A).

break [duration]

Send a break signal for duration*0.25 seconds to this window. For non-Posix systems the
time interval may be rounded up to full seconds. Most useful if a character device is
attached to the window rather than a shell process (See also chapter "WINDOW TYPES"). The
maximum duration of a break signal is limited to 15 seconds.

blanker

Activate the screen blanker. First the screen is cleared. If no blanker program is
defined, the cursor is turned off, otherwise, the program is started and it's output is
written to the screen. The screen blanker is killed with the first keypress, the read key
is discarded.
This command is normally used together with the "idle" command.

blankerprg [program args]

Defines a blanker program. Disables the blanker program if an empty argument is given.
Shows the currently set blanker program if no arguments are given.

breaktype [tcsendbreak|TIOCSBRK |TCSBRK]

Choose one of the available methods of generating a break signal for terminal devices.
This command should affect the current window only. But it still behaves identical to
"defbreaktype". This will be changed in the future. Calling "breaktype" with no parameter
displays the break method for the current window.

bufferfile [exchange-file]

Change the filename used for reading and writing with the paste buffer. If the optional
argument to the "bufferfile" command is omitted, the default setting
("/tmp/screen-exchange") is reactivated. The following example will paste the system's
password file into the screen window (using the paste buffer, where a copy remains):

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

bumpleft

Swaps window with previous one on window list.

bumpright

Swaps window with next one on window list.

c1 [on|off]

Change c1 code processing. "C1 on" 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 "defc1" command. Users with fonts that have usable characters in the c1
positions may want to turn this off.

caption always|splitonly [string]
caption string [string]

This command controls the display of the window captions. Normally a caption is only used
if more than one window is shown on the display (split screen mode). But if the type is
set to always screen shows a caption even if only one window is displayed. The default is
splitonly.

The second form changes the text used for the caption. You can use all escapes from the
"STRING ESCAPES" chapter. Screen uses a default of `%3n %t'.

You can mix both forms by providing a string as an additional argument.

charset set

Change the current character set slot designation and charset mapping. The first four
character of 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 (set is
padded to six characters internally by appending '.' chars). New windows have "BBBB02" as
default charset, unless a "encoding" command is active.
The current setting can be viewed with the "info" command.

chdir [directory]

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

cjkwidth [ on | off ]

Treat ambiguous width characters as full/half width.

clear

Clears the current window and saves its image to the scrollback buffer.

collapse

Reorders window on window list, removing number gaps between them.

colon [prefix]

Allows you to enter ".screenrc" command lines. Useful for on-the-fly modification of key
bindings, specific window creation and changing settings. Note that the "set" keyword no
longer exists! 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 screen, you may regard "C-a esc" (copy
mode) as its `Vi command mode'.

command [-c class]

This command has the same effect as typing the screen escape character (^A). It is
probably only useful for key bindings. If the "-c" option is given, select the specified
command class. See also "bind" and "bindkey".

compacthist [on|off]

This tells screen whether to suppress trailing blank lines when scrolling up text into the
history buffer.

console [on|off]

Grabs or un-grabs the machines console output to a window. Note: Only the owner of
/dev/console can grab the console output. This command is only available if the machine
supports the ioctl TIOCCONS.

copy

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:
Movement keys:
h, C-h, or left arrow move the cursor left.
j, C-n, or down arrow move the cursor down.
k, C-p, or up arrow move the cursor up.
l ('el') or right arrow move the cursor right.
0 (zero) or C-a move to the leftmost column.
+ and - positions one line up and down.
H, M and L move the cursor to the leftmost column of the top, center or bottom line of
the window.
| moves to the specified absolute column.
g or home moves to the beginning of the buffer.
G or end moves to the specified absolute line (default: end of buffer).
% jumps to the specified percentage of the buffer.
^ or $ move to the leftmost column, to the first or last non-whitespace character on the
line.
w, b, and e move the cursor word by word.
B, E move the cursor WORD by WORD (as in vi).
f/F, t/T move the cursor forward/backward to the next occurence of the target. (eg,
'3fy' will move the cursor to the 3rd 'y' to the right.)
; and , Repeat the last f/F/t/T command in the same/opposite direction.
C-e and C-y scroll the display up/down by one line while preserving the cursor position.
C-u and C-d scroll the display up/down by the specified amount of lines while preserving
the cursor position. (Default: half screen-full).
C-b and C-f scroll the display up/down a full screen.

Note:
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.

Marking:
The copy range is specified by setting two marks. The text between these marks will be
highlighted. Press:
space or enter to set the first or second mark respectively. If mousetrack is set to
`on', marks can also be set using left mouse click.
Y and y used to mark one whole line or to mark from start of line.
W marks exactly one word.
Repeat count:
Any of these commands can be prefixed with a repeat count number by pressing digits
0..9 which is taken as a repeat count.
Example: "C-a C-[ H 10 j 5 Y" will copy lines 11 to 15 into the paste buffer.
Searching:
/ Vi-like search forward.
? Vi-like search backward.
C-a s Emacs style incremental search forward.
C-r Emacs style reverse i-search.
n Find next search pattern.
N Find previous search pattern.
Specials:
There are however some keys that act differently than in vi. Vi does not allow one to
yank rectangular blocks of text, but screen does. Press:
c or C to set the left or right margin respectively. If no repeat count is given, both
default to the current cursor position.
Example: Try this on a rather full text screen: "C-a [ M 20 l SPACE c 10 l 5 j C
SPACE".

This moves one to the middle line of the screen, moves in 20 columns left, marks the
beginning of the 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:
"C-a [ M 20 l SPACE 10 l 5 j SPACE"

and notice the difference in the amount of text copied.
J joins lines. It toggles between 4 modes: lines separated by a newline character (012),
lines glued seamless, lines separated by a single whitespace and comma separated
lines. Note that you can prepend the newline character with a carriage return
character, by issuing a "crlf on".
v or V is for all the vi users with ":set numbers" - it toggles the left margin between
column 9 and 1. Press
a 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.
A toggles in append mode and sets a (second) mark.
> 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.
This example demonstrates how to dump the whole scrollback buffer to that file: "C-A [
g SPACE G $ >".
C-g gives information about the current line and column.
x or o exchanges the first mark and the current cursor position. You can use this to
adjust an already placed mark.
C-l ('el') will redraw the screen.
@ does nothing. Does not even exit copy mode.
All keys not described here exit copy mode.

copy_reg [key]

No longer exists, use "readreg" instead.

crlf [on|off]

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. When no parameter is given, the state is toggled.

debug on|off

Turns runtime debugging on or off. If 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 "SCREEN" process correctly. Debug output from attacher
processes can only be turned off once and forever.

defc1 on|off

Same as the c1 command except that the default setting for new windows is changed. Initial
setting is `on'.

defautonuke on|off

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

defbce on|off

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

defbreaktype [tcsendbreak|TIOCSBRK |TCSBRK]

Choose one of the available methods of generating a break signal for terminal devices. The
preferred methods are tcsendbreak and TIOCSBRK. The third, TCSBRK, blocks the complete
screen session for the duration of the break, but it may be the only way to generate long
breaks. Tcsendbreak and TIOCSBRK may or may not produce long breaks with spikes (e.g. 4
per second). This is not only system-dependent, this also differs between serial board
drivers. Calling "defbreaktype" with no parameter displays the current setting.

defcharset [set]

Like the charset command except that the default setting for new windows is changed. Shows
current default if called without argument.

defescape xy

Set the default command characters. This is equivalent to the "escape" except that it is
useful multiuser sessions only. In a multiuser session "escape" changes the command
character of the calling user, where "defescape" changes the default command characters
for users that will be added later.

defflow on|off|auto [interrupt]

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

defgr on|off

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

defhstatus [status]

The hardstatus line that all new windows will get is set to status. This command is
useful to make the hardstatus of every window display the window number or title or the
like. 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
misinterpretation of program generated hardstatus lines impossible. If the parameter
status is omitted, the current default string is displayed. Per default the hardstatus
line of new windows is empty.

defencoding enc

Same as the encoding command except that the default setting for new windows is changed.
Initial setting is the encoding taken from the terminal.

deflog on|off

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

deflogin on|off

Same as the login command except that the default setting for new windows is changed. This
is initialized with `on' as distributed (see config.h.in).

defmode mode

The mode of each newly allocated pseudo-tty is set to mode. Mode is an octal number.
When no "defmode" command is given, mode 0622 is used.

defmonitor on|off

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

defmousetrack on|off

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

defnonblock on|off|numsecs

Same as the nonblock command except that the default setting for displays is changed.
Initial setting is `off'.

defobuflimit limit

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

defscrollback num

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

defshell command

Synonym to the shell .screenrc command. See there.

defsilence on|off

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

defslowpaste msec"

Same as the slowpaste command except that the default setting for new windows is changed.
Initial setting is 0 milliseconds, meaning `off'.

defutf8 on|off

Same as the utf8 command except that the default setting for new windows is changed.
Initial setting is `on' if screen was started with "-U", otherwise `off'.

defwrap on|off

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

defwritelock on|off|auto

Same as the writelock command except that the default setting for new windows is changed.
Initially writelocks will off.

defzombie [keys]

Synonym to the zombie command. Both currently change the default. See there.

detach [-h]

Detach the screen session (disconnect it from the terminal and put it into the
background). This returns you to the shell where you invoked screen. A detached screen
can be resumed by invoking screen with the -r option (see also section "COMMAND-LINE
OPTIONS"). The -h option tells screen to immediately close the connection to the terminal
("hangup").

dinfo

Show what screen thinks about your terminal. Useful if you want to know why features like
color or the alternate charset don't work.

displays

Shows a tabular listing of all currently connected user front-ends (displays). This is
most useful for multiuser sessions. The following keys can be used in displays list:
k, C-p, or up Move up one line.
j, C-n, or down Move down one line.
C-a or home Move to the first line.
C-e or end Move to the last line.
C-u or C-d Move one half page up or down.
C-b or C-f Move one full page up or down.
mouseclick Move to the selected line. Available when "mousetrack" is set to on.
space Refresh the list
d Detach that display
D Power detach that display
C-g, enter, or escape Exit the list

The following is an example of what "displays" could look like:

xterm 80x42 jnweiger@/dev/ttyp4 0(m11) &rWx
facit 80x24 mlschroe@/dev/ttyhf nb 11(tcsh) rwx
xterm 80x42 jnhollma@/dev/ttyp5 0(m11) &R.x
(A) (B) (C) (D) (E) (F)(G) (H)(I)

The legend is as follows:
(A) The terminal type known by screen for this display.
(B) Displays geometry as width x height.
(C) Username who is logged in at the display.
(D) Device name of the display or the attached device
(E) Display is in blocking or nonblocking mode. The available modes are "nb", "NB", "Z<",
"Z>", and "BL".
(F) Number of the window
(G) Name/title of window
(H) Whether the window is shared
(I) Window permissions. Made up of three characters:
(1st character)
‘-’ : no read
‘r’ : read
‘R’ : read only due to foreign wlock
(2nd character)
‘-’ : no write
‘.’ : write suppressed by foreign wlock
‘w’ : write
‘W’ : own wlock
(3rd character)
‘-’ : no execute
‘x’ : execute

"Displays" needs a region size of at least 10 characters wide and 5 characters high in
order to display.

digraph [preset[unicode-value]]

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), screen will treat the following characters (up to three) as an
octal number instead. The optional argument preset is treated as user input, thus one can
create an "umlaut" key. For example the command "bindkey ^K digraph '"'" enables the user
to generate an a-umlaut by typing CTRL-K a. When a non-zero unicode-value is specified, a
new digraph is created with the specified preset. The digraph is unset if a zero value is
provided for the unicode-value.

dumptermcap

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

echo [-n] message

The echo command may be used to annoy screen users with a 'message of the day'. Typically
installed in a global /etc/screenrc. The option "-n" may be used to suppress the line
feed. See also "sleep". Echo is also useful for online checking of environment
variables.

encoding enc [enc]

Tell screen how to interpret the input/output. The first argument sets the encoding of the
current window. Each window can emulate a different encoding. The optional second
parameter overwrites the encoding of the connected terminal. It should never be needed as
screen uses the locale setting to detect the encoding. There is also a way to select a
terminal encoding depending on the terminal type by using the "KJ" termcap entry.

Supported encodings are eucJP, SJIS, eucKR, eucCN, Big5, GBK, KOI8-R, CP1251, UTF-8,
ISO8859-2, ISO8859-3, ISO8859-4, ISO8859-5, ISO8859-6, ISO8859-7, ISO8859-8, ISO8859-9,
ISO8859-10, ISO8859-15, jis.

See also "defencoding", which changes the default setting of a new window.

escape xy

Set the command character to x and the character generating a literal command character
(by triggering the "meta" command) to y (similar to the -e option). Each argument is
either a single character, a two-character sequence of the form "^x" (meaning "C-x"), a
backslash followed by an octal number (specifying the ASCII code of the character), or a
backslash followed by a second character, such as "\^" or "\\". The default is "^Aa".

eval command1 [command2 …]

Parses and executes each argument as separate command.

exec [[fdpat] newcommand [args …]]

Run a unix subprocess (specified by an executable path newcommand and its optional
arguments) in the current window. The flow of data between newcommands
stdin/stdout/stderr, the process originally started in the window (let us call it
"application-process") and screen itself (window) is controlled by the file descriptor
pattern fdpat. This pattern is basically a three character sequence representing stdin,
stdout and stderr of newcommand. A dot (.) connects the file descriptor to screen. An
exclamation mark (!) causes the file descriptor to be connected to the application-
process. A colon (:) combines both. User input will go to newcommand unless newcommand
receives the application-process' output (fdpats first character is `!' or `:') or a pipe
symbol (|) is added (as a fourth character) to the end of fdpat.
Invoking `exec' without arguments shows name and arguments of the currently running
subprocess in this window. Only one subprocess a time can be running in each window.
When a subprocess is running the `kill' command will affect it instead of the windows
process.
Refer to the postscript file `doc/fdpat.ps' for 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 the usual pty that has the application-
process on its slave side. The box marked `P' is the secondary pty that now has screen at
its master side.

Abbreviations:
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 `!'.

Examples:

exec … /bin/sh
exec /bin/sh
!/bin/sh

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.

exec !.. stty 19200
exec ! stty 19200
!!stty 19200

Set the speed of the window's tty. If your stty command operates on stdout, then add
another `!'.

exec !..| less
|less

This adds a pager to the window output. The special character `|' is needed to give the
user control over the pager although it gets its input from the window's process. This
works, because less listens on stderr (a behavior that screen would not expect without the
`|') when its stdin is not a tty. Less versions newer than 177 fail miserably here; good
old pg still works.

!:sed -n s/.*Error.*/\007/p

Sends window output to both, the user and the sed command. The sed inserts an additional
bell character (oct. 007) to the window output seen by screen. This will cause "Bell in
window x" messages, whenever the string "Error" appears in the window.

fit

Change the window size to the size of the current region. This command is needed because
screen doesn't adapt the window size automatically if the window is displayed more than
once.

flow [on|off|auto]

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
"FLOW-CONTROL" later on in this document for full details and note, that this is subject
to change in future releases. Default is set by `defflow'.

focus [up|down|top|bottom]

Move the input focus to the next region. This is done in a cyclic way so that the top
region is selected after the bottom one. If no subcommand is given it defaults to `down'.
`up' cycles in the opposite order, `top' and `bottom' go to the top and bottom region
respectively. Useful bindings are (j and k as in vi)
bind j focus down
bind k focus up
bind t focus top
bind b focus bottom
Note that k is traditionally bound to the kill command.

focusminsize [ ( width|max|_ ) ( height|max|_ ) ]

This forces any currently selected region to be automatically resized at least a certain
width and height. All other surrounding regions will be resized in order to accommodate.
This constraint follows everytime the "focus" command is used. The "resize" command can be
used to increase either dimension of a region, but never below what is set with
"focusminsize". The underscore `_' is a synonym for max. Setting a width and height of `0
0' (zero zero) will undo any constraints and allow for manual resizing. Without any
parameters, the minimum width and height is shown.

gr [on|off]

Turn GR charset switching on/off. Whenever screen sees an input character with the 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 "defgr") is not to process GR switching because
otherwise the ISO88591 charset would not work.

group [grouptitle]

Change or show the group the current window belongs to. Windows can be moved around
between different groups by specifying the name of the destination group. Without
specifying a group, the title of the current group is displayed.

hardcopy [-h] [file]

Writes out the currently displayed image to the file file, or, if no filename is
specified, to hardcopy.n in the default directory, where n is the number of the current
window. This either appends or overwrites the file if it exists. See below. If the
option -h is specified, dump also the contents of the scrollback buffer.

hardcopy_append on|off

If set to "on", screen will append to the "hardcopy.n" files created by the command "C-a
h", otherwise these files are overwritten each time. Default is `off'.

hardcopydir directory

Defines a directory where hardcopy files will be placed. If unset, hardcopys are dumped in
screen's current working directory.

hardstatus [on|off]
hardstatus [always]firstline|lastline|message|ignore [string]
hardstatus string [string]

This command configures the use and emulation of the terminal's hardstatus line. The first
form toggles whether screen will use the hardware status line to display messages. If the
flag is set to `off', these messages are overlaid in reverse video mode at the display
line. The default setting is `on'.

The second form tells screen what to do if the terminal doesn't have a hardstatus line
(i.e. the termcap/terminfo capabilities "hs", "ts", "fs" and "ds" are not set). When
"firstline/lastline" is used, screen will reserve the first/last line of the display for
the hardstatus. "message" uses screen's message mechanism and "ignore" tells screen never
to display the hardstatus. If you prepend the word "always" to the type (e.g.,
"alwayslastline"), screen will use the type even if the terminal supports a hardstatus.

The third form specifies the contents of the hardstatus line. '%h' is used as default
string, i.e., the stored hardstatus of the current window (settable via "ESC]0;<string>^G"
or "ESC_<string>ESC\") is displayed. You can customize this to any string you like
including the escapes from the "STRING ESCAPES" chapter. If you leave out the argument
string, the current string is displayed.

You can mix the second and third form by providing the string as additional argument.

height [-w|-d] [lines [cols]]

Set the display height to a specified number of lines. When no argument is given it
toggles between 24 and 42 lines display. You can also specify a width if you want to
change both values. The -w option tells screen to leave the display size unchanged and
just set the window size, -d vice versa.

help [-c class]

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.
If the "-c" option is given, display all bound commands for the specified command class.
See also "DEFAULT KEY BINDINGS" section.

history

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

hstatus status

Change the window's hardstatus line to the string status.

idle [timeout [cmd args]]

Sets a command that is run after the specified number of seconds inactivity is reached.
This command will normally be the "blanker" command to create a screen blanker, but it can
be any screen command. If no command is specified, only the timeout is set. A timeout of
zero (or the special timeout off) disables the timer. If no arguments are given, the
current settings are displayed.

ignorecase [on|off]

Tell screen to ignore the case of characters in searches. Default is `off'. Without any
options, the state of ignorecase is toggled.

info

Uses the message line to display some information about the current window: the cursor
position in the form "(column,row)" starting with "(1,1)", the terminal width and height
plus the size of the scrollback buffer in lines, like in "(80,24)+50", the current state
of window XON/XOFF flow control is shown like this (See also section FLOW CONTROL):

+flow automatic flow control, currently on.
-flow automatic flow control, currently off.
+(+)flow flow control enabled. Agrees with automatic control.
-(+)flow flow control disabled. Disagrees with automatic control.
+(-)flow flow control enabled. Disagrees with automatic control.
-(-)flow flow control disabled. Agrees with automatic control.

The current line wrap setting (`+wrap' indicates enabled, `-wrap' not) is also shown. The
flags `ins', `org', `app', `log', `mon' or `nored' are displayed when the window is in
insert mode, origin mode, application-keypad mode, has output logging, activity monitoring
or partial redraw enabled.

The currently active character set (G0, G1, G2, or G3) and in square brackets the terminal
character sets that are currently designated as G0 through G3 is shown. If the window is
in UTF-8 mode, the string "UTF-8" is shown instead.

Additional modes depending on the type of the window are displayed at the end of the
status line (See also chapter "WINDOW TYPES").
If the state machine of the terminal emulator is in a non-default state, the info line is
started with a string identifying the current state.
For system information use the "time" command.

ins_reg [key]

No longer exists, use "paste" instead.

kill

Kill current window.
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
screen (your display) switches to another window. When the last window is destroyed,
screen exits. After a kill screen switches to the previously displayed window.
Note: Emacs users should keep this command in mind, when killing a line. It is
recommended not to use "C-a" as the screen escape key or to rebind kill to "C-a K".

lastmsg

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 "msgwait" and "msgminwait" for fine
tuning.

layout new [title]

Create a new layout. The screen will change to one whole region and be switched to the
blank window. From here, you build the regions and the windows they show as you desire.
The new layout will be numbered with the smallest available integer, starting with zero.
You can optionally give a title to your new layout. Otherwise, it will have a default
title of "layout". You can always change the title later by using the command layout
title.

layout remove [n|title]

Remove, or in other words, delete the specified layout. Either the number or the title can
be specified. Without either specification, screen will remove the current layout.

Removing a layout does not affect your set windows or regions.

layout next

Switch to the next layout available

layout prev

Switch to the previous layout available

layout select [n|title]

Select the desired layout. Either the number or the title can be specified. Without either
specification, screen will prompt and ask which screen is desired. To see which layouts
are available, use the layout show command.

layout show

List on the message line the number(s) and title(s) of the available layout(s). The
current layout is flagged.

layout title [title]

Change or display the title of the current layout. A string given will be used to name the
layout. Without any options, the current title and number is displayed on the message
line.

layout number [n]

Change or display the number of the current layout. An integer given will be used to
number the layout. Without any options, the current number and title is displayed on the
message line.

layout attach [title|:last]

Change or display which layout to reattach back to. The default is :last, which tells
screen to reattach back to the last used layout just before detachment. By supplying a
title, You can instruct screen to reattach to a particular layout regardless which one was
used at the time of detachment. Without any options, the layout to reattach to will be
shown in the message line.

layout save [n|title]

Remember the current arrangement of regions. When used, screen will remember the
arrangement of vertically and horizontally split regions. This arrangement is restored
when a screen session is reattached or switched back from a different layout. If the
session ends or the screen process dies, the layout arrangements are lost. The layout dump
command should help in this siutation. If a number or title is supplied, screen will
remember the arrangement of that particular layout. Without any options, screen will
remember the current layout.

Saving your regions can be done automatically by using the layout autosave command.

layout autosave [on|off]

Change or display the status of automatcally saving layouts. The default is on, meaning
when screen is detached or changed to a different layout, the arrangement of regions and
windows will be remembered at the time of change and restored upon return. If autosave is
set to off, that arrangement will only be restored to either to the last manual save,
using layout save, or to when the layout was first created, to a single region with a
single window. Without either an on or off, the current status is displayed on the message
line.

layout dump [filename]

Write to a file the order of splits made in the current layout. This is useful to recreate
the order of your regions used in your current layout. Only the current layout is
recorded. While the order of the regions are recorded, the sizes of those regions and
which windows correspond to which regions are not. If no filename is specified, the
default is layout-dump, saved in the directory that the screen process was started in. If
the file already exists, layout dump will append to that file. As an example:

C-a : layout dump /home/user/.screenrc

will save or append the layout to the user's .screenrc file.

license

Display the disclaimer page. This is done whenever screen is started without options,
which should be often enough. See also the "startup_message" command.

lockscreen

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 screen is started) and is
executed with the user's uid and gid.
Warning: When you leave other shells unlocked and you have no password set on screen, the
lock is void: One could easily re-attach from an unlocked shell. This feature should
rather be called `lockterminal'.

log [on|off]

Start/stop writing output of the current window to a file "screenlog.n" in the window's
default directory, where n 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'.

logfile filename
logfile flush secs

Defines the name the log files will get. The default is "screenlog.%n". The second form
changes the number of seconds screen will wait before flushing the logfile buffer to the
file-system. The default value is 10 seconds.

login [on|off]

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 "on" for a screen that runs
under suid-root. Use the "deflogin" command to change the default login state for new
windows. Both commands are only present when screen has been compiled with utmp support.

logtstamp [on|off]
logtstamp after [secs]
logtstamp string [string]

This command controls logfile time-stamp mechanism of screen. If time-stamps are turned
"on", screen adds a string containing the current time to the logfile after two minutes of
inactivity. When output continues and more than another two minutes have passed, a second
time-stamp is added to document the restart of the output. You can change this timeout
with the second form of the command. The third form is used for customizing the time-stamp
string (`-- %n:%t -- time-stamp -- %M/%d/%y %c:%s --\n' by default).

mapdefault

Tell screen that the next input character should only be looked up in the default bindkey
table. See also "bindkey".

mapnotnext

Like mapdefault, but don't even look in the default bindkey table.

maptimeout [timeout]

Set the inter-character timer for input sequence detection to a timeout of timeout ms. The
default timeout is 300ms. Maptimeout with no arguments shows the current setting. See
also "bindkey".

markkeys string

This is a method of changing the keymap used for copy/history mode. The string is made up
of oldchar=newchar pairs which are separated by `:'. Example: The string "B=^B:F=^F" 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 "markkeys h=^B:l=^F:$=^E"
would set the mode for an emacs-style binding. If your terminal sends characters, that
cause you to abort copy mode, then this command may help by binding these characters to do
nothing. The no-op character is `@' and is used like this: "markkeys @=L=H" if you do not
want to use the `H' or `L' commands any longer. As shown in this example, multiple keys
can be assigned to one function in a single statement.

maxwin num

Set the maximum window number screen will create. Doesn't affect already existing windows.
The number can be increased only when there are no existing windows.

meta

Insert the command character (C-a) in the current window's input stream.

monitor [on|off]

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.

mousetrack [on|off]

This command determines whether screen will watch for mouse clicks. When this command is
enabled, regions that have been split in various ways can be selected by pointing to them
with a mouse and left-clicking them. Without specifying on or off, the current state is
displayed. The default state is determined by the "defmousetrack" command.

msgminwait sec

Defines the time screen delays a new message when one message is currently displayed. The
default is 1 second.

msgwait sec

Defines the time a message is displayed if screen is not disturbed by other activity. The
default is 5 seconds.

multiuser on|off

Switch between singleuser and multiuser mode. Standard screen operation is singleuser. In
multiuser mode the commands `acladd', `aclchg', `aclgrp' and `acldel' can be used to
enable (and disable) other users accessing this screen session.

nethack on|off

Changes the kind of error messages used by screen. When you are familiar with the game
"nethack", you may enjoy the nethack-style messages which will often blur the facts a
little, but are much funnier to read. Anyway, standard messages often tend to be unclear
as well.
This option is only available if screen was compiled with the NETHACK flag defined. The
default setting is then determined by the presence of the environment variable
$NETHACKOPTIONS and the file ~/.nethackrc - if either one is present, the default is on.

next

Switch to the next window. This command can be used repeatedly to cycle through the list
of windows.

nonblock [on|off|numsecs]

Tell screen how to deal with user interfaces (displays) that cease to accept output. This
can happen if a user presses ^S or a TCP/modem connection gets cut but no hangup is
received. If nonblock is off (this is the default) screen waits until the display restarts
to accept the output. If nonblock is on, screen waits until the timeout is reached (on is
treated as 1s). If the display still doesn't receive characters, screen will consider it
"blocked" and stop sending characters to it. If at some time it restarts to accept
characters, screen will unblock the display and redisplay the updated window contents.

number [[+|-]n]

Change the current window's number. If the given number n is already used by another
window, both windows exchange their numbers. If no argument is specified, the current
window number (and title) is shown. Using `+' or `-' will change the window's number by
the relative amount specified.

obuflimit [limit]

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.

only

Kill all regions but the current one.

other

Switch to the window displayed previously. If this window does no longer exist, other has
the same effect as next.

partial on|off

Defines whether the display should be refreshed (as with redisplay) after switching to the
current window. This command only affects the current window. To immediately affect all
windows use the allpartial command. Default is `off', of course. This default is fixed,
as there is currently no defpartial command.

password [crypted_pw]

Present a crypted password in your ".screenrc" file and screen will ask for it, whenever
someone attempts to resume a detached. This is useful if you have privileged programs
running under 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, screen prompts twice for typing a password and places its encryption in the
paste buffer. Default is `none', this disables password checking.

paste [registers [dest_reg]]

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 copy, history and readbuf commands. Other registers can be filled with the register,
readreg and paste commands. If paste 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 "paste" 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.

pastefont [on|off]

Tell screen to include font information in the paste buffer. The default is not to do so.
This command is especially useful for multi character fonts like kanji.

pow_break

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

pow_detach

Power detach. Mainly the same as detach, but also sends a HANGUP signal to the parent
process of screen. CAUTION: This will result in a logout, when screen was started from
your login-shell.

pow_detach_msg [message]

The message 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. Without parameter,
the current message is shown.

prev

Switch to the window with the next lower number. This command can be used repeatedly to
cycle through the list of windows.

printcmd [cmd]

If cmd is not an empty string, screen will not use the terminal capabilities "po/pf" if it
detects an ansi print sequence ESC [ 5 i, but pipe the output into cmd. This should
normally be a command like "lpr" or "'cat > /tmp/scrprint'". printcmd without a command
displays the current setting. The ansi sequence ESC \ ends printing and closes the pipe.
Warning: Be careful with this command! If other user have write access to your terminal,
they will be able to fire off print commands.

process [key]

Stuff the contents of the specified register into screen'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.

quit

Kill all windows and terminate screen. Note that on VT100-style terminals the keys C-4
and C-\ 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 "bind '^\'") to
remove a key binding.

readbuf [-e encoding] [filename]

Reads the contents of the specified file into the paste buffer. You can tell screen the
encoding of the file via the -e option. If no file is specified, the screen-exchange
filename is used. See also "bufferfile" command.

readreg [-e encoding] [register [filename]]

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
readbuf reads the screen-exchange file into the paste buffer. You can tell screen the
encoding of the file via the -e option. The following example will paste the system's
password file into the screen window (using register p, where a copy remains):

C-a : readreg p /etc/passwd
C-a : paste p

redisplay

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

register [-e encoding] key string

Save the specified string to the register key. The encoding of the string can be
specified via the -e option. See also the "paste" command.

remove

Kill the current region. This is a no-op if there is only one region.

removebuf

Unlinks the screen-exchange file used by the commands "writebuf" and "readbuf".

rendition bell | monitor | silence | so attr [color]

Change the way screen renders the titles of windows that have monitor or bell flags set in
caption or hardstatus or windowlist. See the "STRING ESCAPES" chapter for the syntax of
the modifiers. The default for monitor is currently "=b " (bold, active colors), for bell
"=ub " (underline, bold and active colors), and "=u " for silence.

reset

Reset the virtual terminal to its "power-on" values. Useful when strange settings (like
scroll regions or graphics character set) are left over from an application.

resize

Resize the current region. The space will be removed from or added to the region below or
if there's not enough space from the region above.

resize +N increase current region height by N

resize -N decrease current region height by N

resize N set current region height to N

resize = make all windows equally high

resize max maximize current region height

resize min minimize current region height

screen [-opts] [n] [cmd [args]|//group]

Establish a new window. The flow-control options (-f, -fn and -fa), title (a.k.a.) option
(-t), login options (-l and -ln) , terminal type option (-T <term>), the all-capability-
flag (-a) and scrollback option (-h <num>) may be specified with each command. The option
(-M) turns monitoring on for this window. The option (-L) turns output logging on for
this window. If an optional number n in the range 0..MAXWIN-1 is given, the window number
n is assigned to the newly created window (or, if this number is already in-use, the next
available number). If a command is specified after "screen", this command (with the given
arguments) is started in the window; otherwise, a shell is created. If //group is
supplied, a container-type window is created in which other windows may be created inside
it.

Thus, if your ".screenrc" contains the lines

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

screen creates a shell window (in window #1) and a window with a TELNET connection to the
machine foobar (with no flow-control using the title "foobar" in window #2) and will write
a logfile ("screenlog.2") of the telnet session. Note, that unlike previous versions of
screen no additional default window is created when "screen" commands are included in your
".screenrc" file. When the initialization is completed, screen switches to the last window
specified in your .screenrc file or, if none, opens a default window #0.
Screen has built in some functionality of "cu" and "telnet". See also chapter "WINDOW
TYPES".

scrollback num

Set the size of the scrollback buffer for the current windows to num lines. The default
scrollback is 100 lines. See also the "defscrollback" command and use "info" to view the
current setting. To access and use the contents in the scrollback buffer, use the "copy"
command.

select [WindowID]

Switch to the window identified by WindowID. This can be a prefix of a window title
(alphanumeric window name) or a window number. The parameter is optional and if omitted,
you get prompted for an identifier. When a new window is established, the first available
number is assigned to this window. Thus, the first window can be activated by "select 0".
The number of windows is limited at compile-time by the MAXWIN configuration parameter
(which defaults to 40). There are two special WindowIDs, "-" selects the internal blank
window and "." selects the current window. The latter is useful if used with screen's "-X"
option.

sessionname [name]

Rename the current session. Note, that for "screen -list" the name shows up with the
process-id prepended. If the argument "name" is omitted, the name of this session is
displayed. Caution: The $STY environment variables will still reflect the old name in pre-
existing shells. This may result in confusion. Use of this command is generally
discouraged. Use the "-S" command-line option if you want to name a new session. The
default is constructed from the tty and host names.

setenv [var [string]]

Set the environment variable var to value string. If only var is specified, the user will
be prompted to enter a value. If no parameters are specified, the user will be prompted
for both variable and value. The environment is inherited by all subsequently forked
shells.

setsid [on|off]

Normally screen uses different sessions and process groups for the windows. If setsid is
turned off, this is not done anymore and all windows will be in the same process group as
the screen backend process. This also breaks job-control, so be careful. The default is
on, of course. This command is probably useful only in rare circumstances.

shell command

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. Typical shells do only minimal
initialization when not started as a login-shell. E.g. Bash will not read your
"~/.bashrc" unless it is a login-shell.

shelltitle title

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 "TITLES (naming windows)".

silence [on|off|sec]

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.

silencewait sec

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

sleep num

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

slowpaste msec

Define the speed at which text is inserted into the current window by the paste ("C-a ]")
command. If the slowpaste value is nonzero text is written character by character.
screen will make a pause of msec 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.

sort

Sort the windows in alphabetical order of the window tiles.

source file

Read and execute commands from file file. Source commands may be nested to a maximum
recursion level of ten. If file is not an absolute path and screen is already processing a
source command, the parent directory of the running source command file is used to search
for the new command file before screen's current directory.

Note that termcap/terminfo/termcapinfo commands only work at startup and reattach time, so
they must be reached via the default screenrc files to have an effect.

sorendition [attr [color]]

This command is deprecated. See "rendition so" instead.

split [-v]

Split the current region into two new ones. All regions on the display are resized to make
room for the new region. The blank window is displayed on the new region. Splits are made
horizontally unless -v is used. Use the "remove" or the "only" command to delete regions.
Use "focus" to toggle between regions.

startup_message on|off

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

stuff [string]

Stuff the string string in the input buffer of the current window. This is like the
"paste" command but with much less overhead. Without a parameter, screen will prompt for
a string to stuff. You cannot paste large buffers with the "stuff" command. It is most
useful for key bindings. See also "bindkey".

su [username [password [password2]]]

Substitute the user of a display. The command prompts for all parameters that are omitted.
If passwords are specified as parameters, they have to be specified un-crypted. The first
password is matched against the systems passwd database, the second password is matched
against the screen password as set with the commands "acladd" or "password". "Su" may be
useful for the screen administrator to test multiuser setups. When the identification
fails, the user has access to the commands available for user nobody. These are "detach",
"license", "version", "help" and "displays".

suspend

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

term term

In each window's environment screen opens, the $TERM variable is set to "screen" by
default. But when no description for "screen" is installed in the local termcap or
terminfo data base, you set $TERM to - say - "vt100". This won't do much harm, as screen
is VT100/ANSI compatible. The use of the "term" command is discouraged for non-default
purpose. That is, one may want to specify special $TERM settings (e.g. vt100) for the
next "screen rlogin othermachine" command. Use the command "screen -T vt100 rlogin
othermachine" rather than setting and resetting the default.

termcap term terminal-tweaks [window-tweaks]
terminfo term terminal-tweaks [window-tweaks]
termcapinfo term terminal-tweaks [window-tweaks]

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. You have to place these commands in one of the
screenrc startup files, as they are meaningless once the terminal emulator is booted.
If your system works uses the terminfo database rather than termcap, 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.
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.

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

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

Some examples:

termcap xterm* LP:hs@

Informs screen that all terminals that begin with `xterm' have firm auto-margins that
allow the last position on the screen to be updated (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 "vt", but only if you don't specify a termcap command for
that terminal.

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

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.)

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

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

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

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

If you would like to fully specify each window's termcap entry, you should instead set the
$SCREENCAP variable prior to running screen. See the discussion on the "VIRTUAL TERMINAL"
in this manual, and the termcap(5) man page for more information on termcap definitions.

time [string]

Uses the message line to display the time of day, the host name, and the load averages
over 1, 5, and 15 minutes (if this is available on your system). For window specific
information, use "info".

If a string is specified, it changes the format of the time report like it is described in
the "STRING ESCAPES" chapter. Screen uses a default of "%c:%s %M %d %H%? %l%?".

title [windowtitle]

Set the name of the current window to windowtitle. If no name is specified, screen prompts
for one. This command was known as `aka' in previous releases.

unbindall

Unbind all the bindings. This can be useful when screen is used solely for its detaching
abilities, such as when letting a console application run as a daemon. If, for some
reason, it is necessary to bind commands after this, use 'screen -X'.

unsetenv var

Unset an environment variable.

utf8 [on|off [on|off]]

Change the encoding used in the current window. If utf8 is enabled, the strings sent to
the window will be UTF-8 encoded and vice versa. Omitting the parameter toggles the
setting. If a second parameter is given, the display's encoding is also changed (this
should rather be done with screen's "-U" option). See also "defutf8", which changes the
default setting of a new window.

vbell [on|off]

Sets the visual bell setting for this window. Omitting the parameter toggles the setting.
If vbell is switched on, but your terminal does not support a visual bell, a `vbell-
message' is displayed in the status line when the bell character (^G) is received. Visual
bell support of a terminal is defined by the termcap variable `vb' (terminfo: 'flash').
Per default, vbell is off, thus the audible bell is used. See also `bell_msg'.

vbell_msg [message]

Sets the visual bell message. message is printed to the status line if the window receives
a bell character (^G), vbell is set to "on", but the terminal does not support a visual
bell. The default message is "Wuff, Wuff!!". Without a parameter, the current message is
shown.

vbellwait sec

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

verbose [on|off]

If verbose is switched on, the command name is echoed, whenever a window is created (or
resurrected from zombie state). Default is off. Without a parameter, the current setting
is shown.

version

Print the current version and the compile date in the status line.

wall message

Write a message to all displays. The message will appear in the terminal's status line.

width [-w|-d] [cols [lines]]

Toggle the window width between 80 and 132 columns or set it to cols columns if an
argument is specified. This requires a capable terminal and the termcap entries "Z0" and
"Z1". See the "termcap" command for more information. You can also specify a new height
if you want to change both values. The -w option tells screen to leave the display size
unchanged and just set the window size, -d vice versa.

windowlist [-b] [-m] [-g]
windowlist string [string]
windowlist title [title]

Display all windows in a table for visual window selection. If screen was in a window
group, screen will back out of the group and then display the windows in that group. If
the -b option is given, screen will switch to the blank window before presenting the list,
so that the current window is also selectable. The -m option changes the order of the
windows, instead of sorting by window numbers screen uses its internal most-recently-used
list. The -g option will show the windows inside any groups in that level and downwards.

The following keys are used to navigate in "windowlist":
k, C-p, or up Move up one line.
j, C-n, or down Move down one line.
C-g or escape Exit windowlist.
C-a or home Move to the first line.
C-e or end Move to the last line.
C-u or C-d Move one half page up or down.
C-b or C-f Move one full page up or down.
0..9 Using the number keys, move to the selected line.
mouseclick Move to the selected line. Available when "mousetrack" is set to "on"
/ Search.
n Repeat search in the forward direction.
N Repeat search in the backward direction.
m Toggle MRU.
g Toggle group nesting.
a All window view.
C-h or backspace Back out the group.
, Switch numbers with the previous window.
. Switch numbers with the next window.
K Kill that window.
space or enter Select that window.

The table format can be changed with the string and title option, the title is displayed
as table heading, while the lines are made by using the string setting. The default
setting is "Num Name%=Flags" for the title and "%3n %t%=%f" for the lines. See the
"STRING ESCAPES" chapter for more codes (e.g. color settings).

"Windowlist" needs a region size of at least 10 characters wide and 6 characters high in
order to display.

windows [ string ]

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 "logged in" 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. The optional string
parameter follows the "STRING ESCAPES" format. If string parameter is passed, the output
size is unlimited. The default command without any parameter is limited to a size of 1024
bytes.

wrap [on|off]

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'. Without any options, the state of wrap
is toggled.

writebuf [-e encoding] [filename]

Writes the contents of the paste buffer to the specified file, or the public accessible
screen-exchange file if no filename is given. This is thought of as a primitive means of
communication between screen users on the same host. If an encoding is specified the paste
buffer is recoded on the fly to match the encoding. The filename can be set with the
bufferfile command and defaults to "/tmp/screen-exchange".

writelock [on|off|auto]

In addition to access control lists, not all users may be able to write to the same window
at once. Per default, writelock is in `auto' mode and grants exclusive input permission to
the user who is the first to switch to the particular window. When he leaves the window,
other users may obtain the writelock (automatically). The writelock of the current window
is disabled by the command "writelock off". If the user issues the command "writelock on"
he keeps the exclusive write permission while switching to other windows.

xoff
xon

Insert a CTRL-s / CTRL-q character to the stdin queue of the current window.

zmodem [off|auto|catch|pass]
zmodem sendcmd [string]
zmodem recvcmd [string]

Define zmodem support for screen. Screen understands two different modes when it detects a
zmodem request: "pass" and "catch". If the mode is set to "pass", screen will relay all
data to the attacher until the end of the transmission is reached. In "catch" mode screen
acts as a zmodem endpoint and starts the corresponding rz/sz commands. If the mode is set
to "auto", screen will use "catch" if the window is a tty (e.g. a serial line), otherwise
it will use "pass".
You can define the templates screen uses in "catch" mode via the second and the third
form.
Note also that this is an experimental feature.

zombie [keys[onerror]]
defzombie [keys]

Per default 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 kill command 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 zombie 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 defzombie. Until we need this as a per window setting, the commands zombie and
defzombie are synonymous.

Optionally you can put the word "onerror" after the keys. This will cause screen to
monitor exit status of the process running in the window. If it exits normally ('0'), the
window disappears. Any other exit value causes the window to become a zombie.

zombie_timeout[seconds]

Per default screen windows are removed from the window list as soon as the windows process
(e.g. shell) exits. If zombie keys are defined (compare with above zombie command), it is
possible to also set a timeout when screen tries to automatically reconnect a dead screen
window.

THE MESSAGE LINE

Screen displays informational messages and other diagnostics in a message line. 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, 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.

The message line facility can be used by an application running in the current window by
means of the ANSI Privacy message control sequence. For instance, from within the shell,
try something like:

echo '<esc>^Hello world from window '$WINDOW'<esc>\\'

where '<esc>' is an escape, '^' is a literal up-arrow, and '\\' turns into a single
backslash.

WINDOW TYPES

Screen provides three different window types. New windows are created with screen's screen
command (see also the entry in chapter "CUSTOMIZATION"). The first parameter to the screen
command defines which type of window is created. The different window types are all
special cases of the normal type. They have been added in order to allow screen to be used
efficiently as a console multiplexer with 100 or more windows.

· The normal window contains a shell (default, if no parameter is given) or any other
system command that could be executed from a shell (e.g. slogin, etc…)

· If a tty (character special device) name (e.g. "/dev/ttya") is specified as the first
parameter, then the window is directly connected to this device. This window type is
similar to "screen cu -l /dev/ttya". Read and write access is required on the device
node, an exclusive open is attempted on the node to mark the connection line as busy.
An optional parameter is allowed consisting of a comma separated list of flags in the
notation used by stty(1):

<baud_rate>
Usually 300, 1200, 9600 or 19200. This affects transmission as well as receive
speed.

cs8 or cs7
Specify the transmission of eight (or seven) bits per byte.

ixon or -ixon
Enables (or disables) software flow-control (CTRL-S/CTRL-Q) for sending data.

ixoff or -ixoff
Enables (or disables) software flow-control for receiving data.

istrip or -istrip
Clear (or keep) the eight bit in each received byte.

You may want to specify as many of these options as applicable. Unspecified options
cause the terminal driver to make up the parameter values of the connection. These
values are system dependent and may be in defaults or values saved from a previous
connection.

For tty windows, the info command shows some of the modem control lines in the status
line. These may include `RTS', `CTS', 'DTR', `DSR', `CD' and more. This depends on the
available ioctl()'s and system header files as well as the on the physical capabilities
of the serial board. Signals that are logical low (inactive) have their name preceded
by an exclamation mark (!), otherwise the signal is logical high (active). Signals not
supported by the hardware but available to the ioctl() interface are usually shown low.

When the CLOCAL status bit is true, the whole set of modem signals is placed inside
curly braces ({ and }). When the CRTSCTS or TIOCSOFTCAR bit is set, the signals `CTS'
or `CD' are shown in parenthesis, respectively.

For tty windows, the command break causes the Data transmission line (TxD) to go low
for a specified period of time. This is expected to be interpreted as break signal on
the other side. No data is sent and no modem control line is changed when a break is
issued.

· If the first parameter is "//telnet", the second parameter is expected to be a host
name, and an optional third parameter may specify a TCP port number (default decimal
23). Screen will connect to a server listening on the remote host and use the telnet
protocol to communicate with that server.
For telnet windows, the command info shows details about the connection in square
brackets ([ and ]) at the end of the status line.

b BINARY. The connection is in binary mode.

e ECHO. Local echo is disabled.

c SGA. The connection is in `character mode' (default: `line mode').

t TTYPE. The terminal type has been requested by the remote host. Screen sends
the name "screen" unless instructed otherwise (see also the command `term').

w NAWS. The remote site is notified about window size changes.

f LFLOW. The remote host will send flow control information. (Ignored at the
moment.)

Additional flags for debugging are x, t and n (XDISPLOC, TSPEED and NEWENV).

For telnet windows, the command break sends the telnet code IAC BREAK (decimal 243) to
the remote host.

This window type is only available if screen was compiled with the BUILTIN_TELNET
option defined.

STRING ESCAPES

Screen provides an escape mechanism to insert information like the current time into
messages or file names. The escape character is '%' with one exception: inside of a
window's hardstatus '^%' ('^E') is used instead.

Here is the full list of supported escapes:

% the escape character itself

a either 'am' or 'pm'

A either 'AM' or 'PM'

c current time HH:MM in 24h format

C current time HH:MM in 12h format

d day number

D weekday name

E sets %? to true if the escape character has been pressed.

f flags of the window, see "windows" for meanings of the various flags

F sets %? to true if the window has the focus

h hardstatus of the window

H hostname of the system

l current load of the system

m month number

M month name

n window number

P sets %? to true if the current region is in copy/paste mode

S session name

s seconds

t window title

u all other users on this window

w all window numbers and names. With '-' qualifier: up to the current window; with
'+' qualifier: starting with the window after the current one.

W all window numbers and names except the current one

x the executed command including arguments running in this windows

X the executed command without arguments running in this windows

y last two digits of the year number

Y full year number

? the part to the next '%?' is displayed only if a '%' escape inside the part expands
to a non-empty string

: else part of '%?'

= pad the string to the display's width (like TeX's hfill). If a number is specified,
pad to the percentage of the window's width. A '0' qualifier tells screen to treat
the number as absolute position. You can specify to pad relative to the last
absolute pad position by adding a '+' qualifier or to pad relative to the right
margin by using '-'. The padding truncates the string if the specified position
lies before the current position. Add the 'L' qualifier to change this.

< same as '%=' but just do truncation, do not fill with spaces

> mark the current text position for the next truncation. When screen needs to do
truncation, it tries to do it in a way that the marked position gets moved to the
specified percentage of the output area. (The area starts from the last absolute
pad position and ends with the position specified by the truncation operator.) The
'L' qualifier tells screen to mark the truncated parts with '…'.

{ attribute/color modifier string terminated by the next "}"

` Substitute with the output of a 'backtick' command. The length qualifier is misused
to identify one of the commands.

The 'c' and 'C' escape may be qualified with a '0' to make screen use zero instead of
space as fill character. The '0' qualifier also makes the '=' escape use absolute
positions. The 'n' and '=' escapes understand a length qualifier (e.g. '%3n'), 'D' and 'M'
can be prefixed with 'L' to generate long names, 'w' and 'W' also show the window flags if
'L' is given.

An attribute/color modifier is is used to change the attributes or the color settings. Its
format is "[attribute modifier] [color description]". The attribute modifier must be
prefixed by a change type indicator if it can be confused with a color description. The
following change types are known:

+ add the specified set to the current attributes

- remove the set from the current attributes

! invert the set in the current attributes

= change the current attributes to the specified set

The attribute set can either be specified as a hexadecimal number or a combination of the
following letters:

d dim
u underline
b bold
r reverse
s standout
B blinking

Colors are coded either as a hexadecimal number or two letters specifying the desired
background and foreground color (in that order). The following colors are known:

k black
r red
g green
y yellow
b blue
m magenta
c cyan
w white
d default color
. leave color unchanged

The capitalized versions of the letter specify bright colors. You can also use the pseudo-
color 'i' to set just the brightness and leave the color unchanged.
A one digit/letter color description is treated as foreground or background color
dependent on the current attributes: if reverse mode is set, the background color is
changed instead of the foreground color. If you don't like this, prefix the color with a
".". If you want the same behavior for two-letter color descriptions, also prefix them
with a ".".
As a special case, "%{-}" restores the attributes and colors that were set before the last
change was made (i.e., pops one level of the color-change stack).

Examples:

"G" set color to bright green

"+b r" use bold red

"= yd" clear all attributes, write in default color on yellow background.

%-Lw%{= BW}%50>%n%f* %t%{-}%+Lw%<
The available windows centered at the current window and truncated to the available
width. The current window is displayed white on blue. This can be used with
"hardstatus alwayslastline".

%?%F%{.R.}%?%3n %t%? [%h]%?
The window number and title and the window's hardstatus, if one is set. Also use a
red background if this is the active focus. Useful for "caption string".

FLOW-CONTROL

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

Each window has an initial flow-control value set with either the -f option or the
"defflow" .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 "flow" command bound to "C-a f".

The automatic flow-switching mode deals with flow control using the TIOCPKT mode (like
"rlogin" does). If the tty driver does not support TIOCPKT, screen tries to 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.

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

TITLES (naming windows)

You can customize each window's name in the window display (viewed with the "windows"
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.

The default name for all shell windows can be set with the "shelltitle" command in the
.screenrc file, while all other windows are created with a "screen" command and thus can
have their name set with the -t option. Interactively, there is the title-string escape-
sequence (<esc>kname<esc>\) and the "title" command (C-a A). The former can be output
from an application to control the window's name under software control, and the latter
will prompt for a name when typed. You can also bind pre-defined names to keys with the
"title" command to set things quickly without prompting.

Finally, screen has a shell-specific heuristic that is enabled by setting the window's
name to "search|name" and arranging to have a null title escape-sequence output as a part
of your prompt. The search portion specifies an end-of-prompt search string, while the
name portion specifies the default shell name for the window. If the name ends in a `:'
screen will add what it believes to be the current command running in the window to the
end of the window's shell name (e.g. "name:cmd"). Otherwise the current command name
supersedes the shell name while it is running.

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

Here's some .screenrc examples:

screen -t top 2 nice top

Adding this line to your .screenrc would start a nice-d version of the "top" command in
window 2 named "top" rather than "nice".

shelltitle '> |csh'
screen 1

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:

/usr/joe/src/dir> trn

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

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

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

% !em
emacs file.c

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

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

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

One thing to keep in mind when adding a null title-escape-sequence to your prompt is that
some shells (like the csh) count all the non-control characters as part of the prompt's
length. If these invisible characters aren't a multiple of 8 then backspacing over a tab
will result in an incorrect display. One way to get around this is to use a prompt like
this:

set prompt='^[[0000m^[k^[\% '

The escape-sequence "<esc>[0000m" 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:

PROMPT_COMMAND='printf "\033k\033\134"'

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

THE VIRTUAL TERMINAL

Each window in a screen session emulates a VT100 terminal, with some extra functions
added. The VT100 emulator is hard-coded, no other terminal types can be emulated.
Usually screen tries to emulate as much of the VT100/ANSI standard as possible. But if
your terminal lacks certain capabilities, the emulation may not be complete. In these
cases screen has to tell the applications that some of the features are missing. This is
no problem on machines using termcap, because screen can use the $TERMCAP variable to
customize the standard screen termcap.

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

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

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

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

Also, you can customize the $TERMCAP value used by screen by using the "termcap" .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 "screen" (and/or
"screen-w") is defined.

Note that screen honors the "terminfo" .screenrc command if the system uses the terminfo
database rather than termcap.

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

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

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): "ESC_<string>ESC\".
As a convenience for xterm users the sequence "ESC]0..2;<string>^G" is also accepted.

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.

The "alternate screen" capability is not enabled by default. Set the altscreen .screenrc
command to enable it.

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

ESC E Next Line

ESC D Index

ESC M Reverse Index

ESC H Horizontal Tab Set

ESC Z Send VT100 Identification String

ESC 7 (V) Save Cursor and Attributes

ESC 8 (V) Restore Cursor and Attributes

ESC [s (A) Save Cursor and Attributes

ESC [u (A) Restore Cursor and Attributes

ESC c Reset to Initial State

ESC g Visual Bell

ESC Pn p Cursor Visibility (97801)

Pn = 6 Invisible

7 Visible

ESC = (V) Application Keypad Mode

ESC > (V) Numeric Keypad Mode

ESC # 8 (V) Fill Screen with E's

ESC \ (A) String Terminator

ESC ^ (A) Privacy Message String (Message Line)

ESC ! Global Message String (Message Line)

ESC k A.k.a. Definition String

ESC P (A) Device Control String. Outputs a string directly to the host
terminal without interpretation.

ESC _ (A) Application Program Command (Hardstatus)

ESC ] 0 ; string ^G (A) Operating System Command (Hardstatus, xterm title hack)

ESC ] 83 ; cmd ^G (A) Execute screen command. This only works if multi-user support
is compiled into screen. The pseudo-user ":window:" is used to
check the access control list. Use "addacl :window: -rwx #?" to
create a user with no rights and allow only the needed
commands.

Control-N (A) Lock Shift G1 (SO)

Control-O (A) Lock Shift G0 (SI)

ESC n (A) Lock Shift G2

ESC o (A) Lock Shift G3

ESC N (A) Single Shift G2

ESC O (A) Single Shift G3

ESC ( Pcs (A) Designate character set as G0

ESC ) Pcs (A) Designate character set as G1

ESC * Pcs (A) Designate character set as G2

ESC + Pcs (A) Designate character set as G3

ESC [ Pn ; Pn H Direct Cursor Addressing

ESC [ Pn ; Pn f same as above

ESC [ Pn J Erase in Display

Pn = None or 0 From Cursor to End of Screen

1 From Beginning of Screen to Cursor

2 Entire Screen

ESC [ Pn K Erase in Line

Pn = None or 0 From Cursor to End of Line

1 From Beginning of Line to Cursor

2 Entire Line

ESC [ Pn X Erase character

ESC [ Pn A Cursor Up

ESC [ Pn B Cursor Down

ESC [ Pn C Cursor Right

ESC [ Pn D Cursor Left

ESC [ Pn E Cursor next line

ESC [ Pn F Cursor previous line

ESC [ Pn G Cursor horizontal position

ESC [ Pn ` same as above

ESC [ Pn d Cursor vertical position

ESC [ Ps ;…; Ps m Select Graphic Rendition

Ps = None or 0 Default Rendition

1 Bold

2 (A) Faint

3 (A) Standout Mode (ANSI: Italicized)

4 Underlined

5 Blinking

7 Negative Image

22 (A) Normal Intensity

23 (A) Standout Mode off (ANSI: Italicized off)

24 (A) Not Underlined

25 (A) Not Blinking

27 (A) Positive Image

30 (A) Foreground Black

31 (A) Foreground Red

32 (A) Foreground Green

33 (A) Foreground Yellow

34 (A) Foreground Blue

35 (A) Foreground Magenta

36 (A) Foreground Cyan

37 (A) Foreground White

39 (A) Foreground Default

40 (A) Background Black

… …

49 (A) Background Default

ESC [ Pn g Tab Clear

Pn = None or 0 Clear Tab at Current Position

3 Clear All Tabs

ESC [ Pn ; Pn r (V) Set Scrolling Region

ESC [ Pn I (A) Horizontal Tab

ESC [ Pn Z (A) Backward Tab

ESC [ Pn L (A) Insert Line

ESC [ Pn M (A) Delete Line

ESC [ Pn @ (A) Insert Character

ESC [ Pn P (A) Delete Character

ESC [ Pn S Scroll Scrolling Region Up

ESC [ Pn T Scroll Scrolling Region Down

ESC [ Pn ^ same as above

ESC [ Ps ;…; Ps h Set Mode

ESC [ Ps ;…; Ps l Reset Mode

Ps = 4 (A) Insert Mode

20 (A) Automatic Linefeed Mode

34 Normal Cursor Visibility

?1 (V) Application Cursor Keys

?3 (V) Change Terminal Width to 132 columns

?5 (V) Reverse Video

?6 (V) Origin Mode

?7 (V) Wrap Mode

?9 X10 mouse tracking

?25 (V) Visible Cursor

?47 Alternate Screen (old xterm code)

?1000 (V) VT200 mouse tracking

?1047 Alternate Screen (new xterm code)

?1049 Alternate Screen (new xterm code)

ESC [ 5 i (A) Start relay to printer (ANSI Media Copy)

ESC [ 4 i (A) Stop relay to printer (ANSI Media Copy)

ESC [ 8 ; Ph ; Pw t Resize the window to `Ph' lines and `Pw' columns (SunView
special)

ESC [ c Send VT100 Identification String

ESC [ x Send Terminal Parameter Report

ESC [ > c Send VT220 Secondary Device Attributes String

ESC [ 6 n Send Cursor Position Report

INPUT TRANSLATION

In order to do a full VT100 emulation screen 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. Screen has a very flexible way of doing this by making it
possible 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 stuff 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. Screen will insert the correct binding
after each reattach. See the bindkey command for further details on the syntax and
examples.

Here is the table of the default key bindings. (A) means that the command is executed if
the keyboard is switched into application mode.

Key name Termcap name Command
______________________________________________________
Cursor up ku stuff \033[A
stuff \033OA (A)
Cursor down kd stuff \033[B
stuff \033OB (A)
Cursor right kr stuff \033[C
stuff \033OC (A)
Cursor left kl stuff \033[D
stuff \033OD (A)
Function key 0 k0 stuff \033[10~
Function key 1 k1 stuff \033OP
Function key 2 k2 stuff \033OQ
Function key 3 k3 stuff \033OR
Function key 4 k4 stuff \033OS
Function key 5 k5 stuff \033[15~
Function key 6 k6 stuff \033[17~
Function key 7 k7 stuff \033[18~
Function key 8 k8 stuff \033[19~
Function key 9 k9 stuff \033[20~
Function key 10 k; stuff \033[21~
Function key 11 F1 stuff \033[23~
Function key 12 F2 stuff \033[24~
Home kh stuff \033[1~
End kH stuff \033[4~
Insert kI stuff \033[2~
Delete kD stuff \033[3~
Page up kP stuff \033[5~
Page down kN stuff \033[6~
Keypad 0 f0 stuff 0
stuff \033Op (A)
Keypad 1 f1 stuff 1
stuff \033Oq (A)
Keypad 2 f2 stuff 2
stuff \033Or (A)
Keypad 3 f3 stuff 3
stuff \033Os (A)
Keypad 4 f4 stuff 4
stuff \033Ot (A)
Keypad 5 f5 stuff 5
stuff \033Ou (A)
Keypad 6 f6 stuff 6
stuff \033Ov (A)
Keypad 7 f7 stuff 7
stuff \033Ow (A)
Keypad 8 f8 stuff 8
stuff \033Ox (A)
Keypad 9 f9 stuff 9
stuff \033Oy (A)
Keypad + f+ stuff +
stuff \033Ok (A)
Keypad - f- stuff -
stuff \033Om (A)
Keypad * f* stuff *
stuff \033Oj (A)
Keypad / f/ stuff /
stuff \033Oo (A)
Keypad = fq stuff =
stuff \033OX (A)
Keypad . f. stuff .
stuff \033On (A)
Keypad , f, stuff ,
stuff \033Ol (A)
Keypad enter fe stuff \015
stuff \033OM (A)

SPECIAL TERMINAL CAPABILITIES

The following table describes all terminal capabilities that are recognized by screen 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.

LP (bool) Terminal has VT100 style margins (`magic margins'). Note that this capability
is obsolete because screen uses the standard 'xn' instead.

Z0 (str) Change width to 132 columns.

Z1 (str) Change width to 80 columns.

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

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'.

G0 (bool) Terminal can deal with ISO 2022 font selection sequences.

S0 (str) Switch charset 'G0' to the specified charset. Default is '\E(%.'.

E0 (str) Switch charset 'G0' back to standard charset. Default is '\E(B'.

C0 (str) Use the string as a conversion table for font '0'. See the 'ac' capability
for more details.

CS (str) Switch cursor-keys to application mode.

CE (str) Switch cursor-keys back to normal mode.

AN (bool) Turn on autonuke. See the 'autonuke' command for more details.

OL (num) Set the output buffer limit. See the 'obuflimit' command for more details.

KJ (str) Set the encoding of the terminal. See the 'encoding' command for valid
encodings.

AF (str) Change character foreground color in an ANSI conform way. This capability
will almost always be set to '\E[3%dm' ('\E[3%p1%dm' on terminfo machines).

AB (str) Same as 'AF', but change background color.

AX (bool) Does understand ANSI set default fg/bg color (\E[39m / \E[49m).

XC (str) Describe a translation of characters to strings depending on the current
font. More details follow in the next section.

XT (bool) Terminal understands special xterm sequences (OSC, mouse tracking).

C8 (bool) Terminal needs bold to display high-intensity colors (e.g. Eterm).

TF (bool) Add missing capabilities to the termcap/info entry. (Set by default).

CHARACTER TRANSLATION

Screen 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:
XC=<charset-mapping>{,,<charset-mapping>}
<charset-mapping> := <designator><template>{,<mapping>}
<mapping> := <char-to-be-mapped><template-arg>

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

A <charset-mapping> tells screen how to map characters in font <designator> ('B': Ascii,
'A': UK, 'K': German, etc.) to strings. Every <mapping> 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
occurrence of '%' in <template> gets substituted with the <template-arg> specified
together with the character. If your strings are not similar at all, then use '%' as a
template and place the full string in <template-arg>. A quoting mechanism was added to
make it possible to use a real '%'. The '\' character quotes the special characters '\',
'%', and ','.

Here is an example:

termcap hp700 'XC=B\E(K%\E(B,\304[,\326\\\\,\334]'

This tells screen how to translate ISOlatin1 (charset 'B') upper case umlaut characters on
a hp700 terminal that has a German charset. '\304' gets translated to '\E(K[\E(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 '\'.

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

This example shows one use of the extension:

termcap xterm 'XC=K%,%\E(B,[\304,\\\\\326,]\334'

Here, a part of the German ('K') charset is emulated on an xterm. If screen has to change
to the 'K' charset, '\E(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 '\304', '\'
to '\326', and ']' to '\334'.

ENVIRONMENT

COLUMNS Number of columns on the terminal (overrides termcap entry).
HOME Directory in which to look for .screenrc.
LINES Number of lines on the terminal (overrides termcap entry).
LOCKPRG Screen lock program.
NETHACKOPTIONS Turns on nethack option.
PATH Used for locating programs to run.
SCREENCAP For customizing a terminal's TERMCAP value.
SCREENDIR Alternate socket directory.
SCREENRC Alternate user screenrc file.
SHELL Default shell program for opening windows (default "/bin/sh"). See also
"shell" .screenrc command.
STY Alternate socket name.
SYSSCREENRC Alternate system screenrc file.
TERM Terminal name.
TERMCAP Terminal description.
WINDOW Window number of a window (at creation time).

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