SCREEN(1) General Commands Manual SCREEN(1)
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 (typi‐
cally interactive shells). Each virtual terminal provides the functions of a DEC VT100 terminal and, in addi‐
tion, 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 win‐
dow; if none are left, screen exits.
Everything you type is sent to the program running in the current window. The only exception to this is the
one keystroke that is used to initiate a command to the window manager. By default, each command begins with
a control-a (abbreviated C-a from now on), and is followed by one other keystroke. The command character 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. 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 charac‐
ters 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 $STY environment
variable) who will use it to create the new window. The above example would start the emacs editor (editing
prog.c) and switch to its window. - Note that you cannot transport environment variables from the invoking
shell to the application (emacs in this case), because it is forked from the parent screen process, not from
the invoking shell.
If "/etc/utmp" is writable by screen, an appropriate record will be written to this file for each window, and
removed when the window is terminated. This is useful for working with "talk", "script", "shutdown", "rsend",
TION" deals with the contents of your .screenrc.
If your terminal is a "true" auto-margin terminal (it doesn't allow the last position on the screen to be
updated without scrolling the screen) consider using a version of your terminal's termcap that has automatic
margins turned off. This will ensure an accurate and optimal update of the screen in all circumstances. Most
terminals nowadays have "magic" margins (automatic margins plus usable last column). This is the VT100 style
type and perfectly suited for screen. If all you've got is a "true" auto-margin terminal screen will be con‐
tent to use it, but updating a character put into the last position on the screen may not be possible until
the screen scrolls or the character is moved into a safe position in some other way. This delay can be short‐
ened by using a terminal with insert-character capability.
COMMAND-LINE OPTIONS
Screen has the following command-line options:
-a include all capabilities (with some minor exceptions) in each window's termcap, even if screen must
redraw parts of the display in order to implement a function.
-A Adapt the sizes of all windows to the size of the current terminal. By default, screen tries to restore
its old window sizes when attaching to resizable terminals (those with "WS" in its description, e.g.
suncmd or some xterm).
-c file
override the default configuration file from "$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 typ‐
ing "C-a d" from screen's controlling terminal. -D is the equivalent to the power detach key. If no ses‐
sion 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 ses‐
sion 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 run‐
-l and -ln
turns login mode on or off (for /etc/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 identifying your screen sessions. Ses‐
sions 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 com‐
mand, 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
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.
-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.
-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 enviroment 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 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 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 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 C-\ (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.
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
$HOME/.screenrc. The command line option -c takes precedence over the above user screenrc files.
Commands in these files are used to set options, bind functions to keys, and to automatically establish one or
more windows at the beginning of your screen session. Commands are listed one per line, with empty lines
being ignored. A command's arguments are separated by tabs or spaces, and may be surrounded by single or dou‐
ble quotes. A `#' turns the rest of the line into a comment, except in quotes. Unintelligible lines are
warned about and ignored. Commands may contain references to environment variables. The syntax is the shell-
like "$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/etc‐
screenrc". 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 user‐
name -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.
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 identi‐
fier 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 dis‐
play(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 cor‐
rectly under "at" looping over windows.
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 pro‐
cesses 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 sec‐
onds. 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 "").
If a command class is specified via the "-c" option, the key is bound for the specified class. Use the "com‐
mand" command to activate a class. Command classes can be used to create multiple command keys or multi-char‐
acter 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 capa‐
bility 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
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
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" chap‐
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. Hard‐
copy 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.
clear
Clears the current window and saves its image to the scrollback buffer.
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 com‐
mand 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 "bind‐
key".
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.
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 cur‐
rent 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 seam‐
less, lines separated by a single whitespace and comma separated lines. Note that you can prepend the new‐
line 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.
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 ses‐
sions 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 hard‐
status 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.
`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" com‐
mand 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 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
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 alter‐
nate charset don't work.
displays
Shows a tabular listing of all currently connected user front-ends (displays). This is most useful for multi‐
user 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
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 ".term‐
cap" 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 newcom‐
mand. 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.
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
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]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 mes‐
sages 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/ter‐
minfo capabilities "hs", "ts", "fs" and "ds" are not set). If the type "lastline" is used, screen will reserve
the 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., "alwayslast‐
line"), 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 com‐
mands, 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 com‐
mand class. See also "DEFAULT KEY BINDINGS" section.
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 nor‐
mally 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-key‐
pad 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 dis‐
played window.
Note: Emacs users should keep this command in mind, when killing a line. It is recommended not to use "C-a"
smallest available integer, starting with zero. You can optionally give a title to your new layout. Other‐
wise, 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. With‐
out 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. With‐
out 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.
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 sec‐
onds.
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 tog‐
gle, 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
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 char‐
acters, that cause you to abort copy mode, then this command may help by binding these characters to do noth‐
ing. 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. With‐
out specifying on or off, the current state is displayed. The default state is determined by the "defmouse‐
track" command.
msgminwait sec
Defines the time screen delays a new message when one message is currently displayed. The default is 1 sec‐
ond.
msgwait sec
Defines the time a message is displayed if screen is not disturbed by other activity. The default is 5 sec‐
onds.
multiuser on|off
Switch between singleuser and multiuser mode. Standard screen operation is singleuser. In multiuser mode the
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 regis‐
ter 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
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" com‐
mand.
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
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 hardsta‐
tus 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 win‐
dow 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
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 speci‐
fied in $SHELL. If the command begins with a '-' character, the shell will be started as 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
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 paramter, 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 sys‐
tems 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 dis‐
couraged 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]
The first argument specifies which terminal(s) should be affected by this definition. You can specify multi‐
ple terminal names by separating them with `|'s. Use `*' to match all terminals and `vt*' to match all termi‐
nals 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 ter‐
minal'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 charac‐
ter-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 min‐
utes (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]
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 zom‐
bie 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-
/ 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
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 pre‐
vious 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)'; win‐
dows 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.
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 fea‐
ture, 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 (automati‐
cally). 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.
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 ini‐
tially 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.
THE MESSAGE LINE
Screen displays informational messages and other diagnostics in a message line. While this line is distrib‐
uted to appear at the bottom of the screen, it can be defined to appear at the top of the screen during compi‐
lation. 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 momentar‐
ily 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.
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, respec‐
tively.
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 lis‐
tening 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:
D weekday name
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: start‐
ing with the window after the current one.
W all window numbers and names except the current one
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 percent‐
age 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 rela‐
tive 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
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 fore‐
ground 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
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 com‐
mand. 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 run‐
ning 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 set‐
ting 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 lat‐
ter 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 speci‐
fies 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 pre‐
vious 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
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 win‐
dow 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.
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 num‐
ber 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 ver‐
batim 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 trans‐
lation string that is used during semi-graphics mode. This string is built like the `acsc' terminfo capabil‐
ity.
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 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 [ 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
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
?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
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 term‐
cap(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.
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 fol‐
low 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:
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").
STY Alternate socket name.
SYSSCREENRC Alternate system screenrc file.
TERM Terminal name.
TERMCAP Terminal description.
WINDOW Window number of a window (at creation time).
FILES
.../screen-4.?.??/etc/screenrc
.../screen-4.?.??/etc/etcscreenrc Examples in the screen distribution package for private and global initial‐
ization files.
$SYSSCREENRC
/etc/screenrc screen initialization commands
$SCREENRC
$HOME/.screenrc Read in after /etc/screenrc
$SCREENDIR/S-<login>
/local/screens/S-<login> Socket directories (default)
/usr/tmp/screens/S-<login> Alternate socket directories.
<socket directory>/.termcap Written by the "termcap" output function
/usr/tmp/screens/screen-exchange or
/tmp/screen-exchange screen `interprocess communication buffer'
hardcopy.[0-9] Screen images created by the hardcopy function
screenlog.[0-9] Output log files created by the log function
/usr/lib/terminfo/?/* or
/etc/termcap Terminal capability databases
/etc/utmp Login records
$LOCKPRG Program that locks a terminal.
SEE ALSO
termcap(5), utmp(5), vi(1), captoinfo(1), tic(1)
AUTHORS
Originally created by Oliver Laumann, this latest version was produced by Juergen Weigert, Michael Schroeder,
Juergen Weigert ([email protected])
Michael Schroeder ([email protected])
Copyright (C) 1987 Oliver Laumann
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General
Public License as published by the Free Software Foundation; either version 3, or (at your option) any later
version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the
implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License along with this program (see the file COPY‐
ING); if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA
CONTRIBUTORS
Ken Beal ([email protected]),
Rudolf Koenig ([email protected]),
Toerless Eckert ([email protected]),
Wayne Davison ([email protected]),
Patrick Wolfe ([email protected], kailand!pat),
Bart Schaefer ([email protected]),
Nathan Glasser ([email protected]),
Larry W. Virden ([email protected]),
Howard Chu ([email protected]),
Tim MacKenzie ([email protected]),
Markku Jarvinen (mta@{cc,cs,ee}.tut.fi),
Marc Boucher ([email protected]),
Doug Siebert ([email protected]),
Ken Stillson ([email protected]),
Ian Frechett ([email protected]),
Brian Koehmstedt ([email protected]),
Don Smith ([email protected]),
Frank van der Linden ([email protected]),
Martin Schweikert ([email protected]),
David Vrona ([email protected]),
E. Tye McQueen (tye%[email protected]),
Matthew Green ([email protected]),
Christopher Williams ([email protected]),
Matt Mosley ([email protected]),
Gregory Neil Shapiro ([email protected]),
Johannes Zellner ([email protected]),
Pablo Averbuj ([email protected]).
VERSION
This is version 4.1.0. Its roots are a merge of a custom version 2.3PR7 by Wayne Davison and several enhance‐
ments to Oliver Laumann's version 2.0. Note that all versions numbered 2.x are copyright by Oliver Laumann.
AVAILABILITY
The latest official release of screen available via anonymous ftp from gnudist.gnu.org, nic.funet.fi or any
other GNU distribution site. The home site of screen is ftp.uni-erlangen.de, in the directory pub/utili‐
ties/screen. The subdirectory `private' contains the latest beta testing release. If you want to help, send a
note to [email protected].
BUGS
· Screen does not make use of hardware tabs.
· Screen must be installed as set-uid with owner root on most systems in order to be able to correctly change
the owner of the tty device file for each window. Special permission may also be required to write the
file "/etc/utmp".
· Entries in "/etc/utmp" are not removed when screen is killed with SIGKILL. This will cause some programs
(like "w" or "rwho") to advertise that a user is logged on who really isn't.
· Screen may give a strange warning when your tty has no utmp entry.
· When the modem line was hung up, screen may not automatically detach (or quit) unless the device driver is
configured to send a HANGUP signal. To detach a screen session use the -D or -d command line option.
· If a password is set, the command line options -d and -D still detach a session without asking.
· Both "breaktype" and "defbreaktype" change the break generating method used by all terminal devices. The
first should change a window specific setting, where the latter should change only the default for new win‐
dows.
· When attaching to a multiuser session, the user's .screenrc file is not sourced. Each user's personal set‐
tings have to be included in the .screenrc file from which the session is booted, or have to be changed
manually.
· A weird imagination is most useful to gain full advantage of all the features.
· Send bug-reports, fixes, enhancements, t-shirts, money, beer & pizza to [email protected].
4th Berkeley Distribution Aug 2003 SCREEN(1)
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