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

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

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

screen emacs prog.c

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

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

Getting Started

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

If you're impatient and want to get started without doing a lot more reading, you should remember this one command: C-a ? (see section Key Binding). Typing these two characters will display a list of the available screen commands and their bindings. Each keystroke is discussed in the section on keystrokes (see section Default Key Bindings). Another section (see section Customizing Screen) 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 to use a version of your terminal's termcap that has automatic margins turned off. This will ensure an accurate and optimal update of the screen in all circumstances. Most terminals nowadays have "magic" margins (automatic margins plus usable last column). This is the VT100 style type and perfectly suited for screen. If all you've got is a "true" auto-margin terminal screen will be content to use it, but updating a character put into the last position on the screen may not be possible until the screen scrolls or the character is moved into a safe position in some other way. This delay can be shortened by using a terminal with insert-character capability.

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

Invoking Screen

Screen has the following command-line options:

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.
Adapt the sizes of all windows to the size of the display. By default, screen may try to restore its old window sizes when attaching to resizable terminals (those with `WS' in their descriptions, e.g. suncmd or some varieties of xterm).
`-c file'
Use file as the user's configuration file instead of the default of `$HOME/.screenrc'.
`-d [pid.sessionname]'
`-D [pid.sessionname]'
Do not start screen, but instead detach a screen session running elsewhere (see section Detach). `-d' has the same effect as typing C-a d from the controlling terminal for the session. `-D' is the equivalent to the power detach key. If no session can be detached, this option is ignored. The combination screen -D -r can be used to log out from a remote terminal and transport the session running there to your current terminal. Note: It is a good idea to check the status of your sessions with screen -list before using this option.
`-e xy'
Set the command character to x, and the character generating a literal command character (when typed after the command character) to y. The defaults are C-a and a, which can be specified as `-e^Aa'. When creating a screen session, this option sets the default command caracter. In a multiuser session all users added will start off with this command character. But when attaching to an already running session, this option only changes the command character of the attaching user. This option is equivalent to the commands defescape or escape respectively. (see section Command Character).
Set flow-control to on, off, or automatic switching mode, respectively. This option is equivalent to the defflow command (see section Flow Control).
`-h num'
Set the history scrollback buffer to be num lines high. Equivalent to the defscrollback command (see section Copying).
Cause the interrupt key (usually C-c) to interrupt the display immediately when flow control is on. This option is equivalent to the interrupt argument to the defflow command (see section Flow Control). Its use is discouraged.
Turn login mode on or off (for `/etc/utmp' updating). This option is equivalent to the deflogin command (see section Login).
Do not start screen, but instead print a list of session identification strings (usually of the form; see section Session Name). Sessions marked `detached' can be resumed with screen -r. Those marked `attached' are running and have a controlling terminal. Sessions marked as `dead' should be thoroughly checked and removed. Ask your system administrator if you are not sure why they died. Remove sessions with the `-wipe' option.
Tell screen that your auto-margin terminal allows programs to write to the last column of the last row of the screen without scrolling. This can also be set in your `.screenrc' by specifying `xn' in a termcap command (see section Termcap).
Tell screen to ignore the $STY environment variable. When this option is used, a new session will always be created, regardless of whether screen is being called from within another screen session or not.
`-r [pid.sessionname]'
`-r sessionowner/[pid.sessionname]'
Resume a detached screen session. No other options (except `-d' or `-D') may be specified, though the session name (see section Session Name) may be needed to distinguish between multiple detached screen sessions. The second form is used to connect to another users screen session which runs in multi-user mode. This indicates that screen should look for sessions in another users directory. This requires setuid-root.
Resume the first appropriate detached screen session. If successful, all other command-line options are ignored. If no detached session exists, start a new session using the specified options, just as if `-R' had not been specified. This option is set by default if screen is run as a login-shell.
`-s program'
Set the default shell to be program. By default, screen uses the value of the environment variable $SHELL, or `/bin/sh' if it is not defined. This option is equivalent to the shell command (see section Shell).
`-S sessionname'
Set the name of the new session to sessionname. This option can be used to specify a meaningful name for the session in place of the default suffix. This name identifies the session for the screen -list and screen -r commands. This option is equivalent to the sessionname command (see section Session Name).
`-t name'
Set the title (name) for the default shell or specified program. This option is equivalent to the shelltitle command (see section Shell).
Print the version number.
List available screens like screen -ls, but remove destroyed sessions instead of marking them as `dead'.
Attach to a session which is already attached elsewhere (multi-display mode).

Customizing Screen

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

The `.screenrc' file

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

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


Customization can also be done online, with this command:

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


A command in screen can either be bound to a key, invoked from a screenrc file, or called from the colon prompt (see section Customizing Screen). As of version 3.3, all commands can be bound to keys, although some may be less useful than others. For a number of real life working examples of the most important commands see the files `etc/screenrc' and `etc/etcscreenrc' of your screen distribution.

In this manual, a command definition looks like this:

-- Command: command [-n] ARG1 [ARG2] ...
This command does something, but I can't remember what.

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

Default Key Bindings

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

The following table shows the default key bindings:

C-a '
C-a "
Prompt for a window identifier and switch. See section Selecting a Window.
C-a 0...9
(select 9)
Switch to window number 0...9. See section Selecting a Window.
C-a C-a
Toggle to the window displayed previously. See section Selecting a Window.
C-a a
Send the command character (C-a) to window. See escape command. See section Command Character.
C-a A
Allow the user to enter a title for the current window. See section Naming Windows (Titles).
C-a b
itemx C-a C-b (break)
Send a break to the tty. See section Break.
C-a B
Close and reopen the tty-line. See section Break.
C-a c
C-a C-c
Create a new window with a shell and switch to that window. See section Screen Command.
C-a C
Clear the screen. See section Clear.
C-a d
C-a C-d
Detach screen from this terminal. See section Detach.
C-a D D
Detach and logout. See section Power Detach.
C-a f
C-a C-f
Cycle flow among `on', `off' or `auto'. See section Flow.
C-a C-g
Toggle visual bell mode. See section Bell.
C-a h
Write a hardcopy of the current window to the file "hardcopy.n". See section hardcopy.
C-a H
Toggle logging of the current window to the file "screenlog.n". See section log.
C-a i
C-a C-i
Show info about the current window. See section Info.
C-a k
C-a C-k
Destroy the current window. See section Kill.
C-a l
C-a C-l
Fully refresh the current window. See section Redisplay.
C-a L
Toggle the current window's login state. See section Login.
C-a m
C-a C-m
Repeat the last message displayed in the message line. See section Display Last Message.
C-a M
(monitor) Toggle monitoring of the current window. See section Monitoring.
C-a n
C-a C-n
Switch to the next window. See section Selecting a Window.
C-a N
Show the number (and title) of the current window. See section Number.
C-a p
C-a C-p
C-a C-h
C-a BackSpace
Switch to the previous window (opposite of C-a n). See section Selecting a Window.
C-a q
C-a C-q
Send a ^Q (ASCII XON) to the current window. See section XON and XOFF.
C-a r
C-a C-r
Toggle the current window's line-wrap setting (turn the current window's automatic margins on or off). See section Wrap.
C-a s
C-a C-s
Send a ^S (ASCII XOFF) to the current window. See section XON and XOFF.
C-a t
C-a C-t
Show the load average and xref. See section Time.
C-a v
Display the version and compilation date. See section Version.
C-a C-v
Enter digraph. See section Digraph.
C-a w
C-a C-w
Show a list of active windows. See section Windows.
C-a W
Toggle between 80 and 132 columns. See section Window Size.
C-a x
C-a C-x
Lock your terminal. See section Lock.
C-a z
C-a C-z
Suspend screen. See section Suspend.
C-a Z
Reset the virtual terminal to its "power-on" values. See section Reset.
C-a .
Write out a `.termcap' file. See section Write out the window's termcap entry.
C-a ?
Show key bindings. See section Help.
C-a C-\
Kill all windows and terminate screen. See section Quit.
C-a :
Enter a command line. See section Colon.
C-a [
C-a C-[
Enter copy/scrollback mode. See section Copying.
C-a ]
C-a C-]
(paste .)
Write the contents of the paste buffer to the stdin queue of the current window. See section Paste.
C-a {
Copy and paste a previous (command) line. See section History.
C-a >
Write the paste buffer out to the screen-exchange file. See section Screen-Exchange.
C-a <
Read the screen-exchange file into the paste buffer. See section Screen-Exchange.
C-a =
Delete the screen-exchange file. See section Screen-Exchange.
C-a _
Start/stop monitoring the current window for inactivity. See section Silence,
C-a ,
Show the copyright page.

Command Summary

acladd usernames
Allow other users in this session. See section Multiuser Session.
aclchg usernames permbits list
Change a user's permissions. See section Multiuser Session.
acldel username
Disallow other user in this session. See section Multiuser Session.
activity message
Set the activity notification message. See section Monitoring.
allpartial state
Set all windows to partial refresh. See section Redisplay.
at [ident][#|*|%] command [args]
Execute a command at other displays or windows. See section At.
autodetach state
Automatically detach the session on SIGHUP. See section Detach.
autonuke state
Enable a clear screen to discard unwritten output. See section Autonuke.
bell_msg message
Set the bell notification message. See section Bell.
bind key [command [args]]
Bind a command to a key. See section The bind command.
bindkey [opts] [string [cmd args]]
Bind a string to a series of keystrokes. See section Bindkey.
break [duration]
Send a break signal to the current window. See section Break.
bufferfile [exchange-file]
Select a file for screen-exchange. See section Screen-Exchange.
c1 [state]
Change c1 code processing. See section Character Processing.
charset set
Change character set slot designation. See section Character Processing.
chdir [directory]
Change the current directory for future windows. See section Chdir.
Clear the window screen. See section Clear.
Enter a screen command. See section Colon.
Simulate the screen escape key. See section Command Character.
console [state]
Grab or ungrab console output. See section Console.
Enter copy mode. See section Copying.
copy_reg [key]
Removed. Use paste instead. See section Registers.
crlf state
Select line break behavior for copying. See section CR/LF.
debug state
Suppress/allow debugging output. See section Debug.
defautonuke state
Select default autonuke behavior. See section Autonuke.
defc1 state
Select default c1 processing behavior. See section Character Processing.
defcharset [set]
Change defaul character set slot designation. See section Character Processing.
defescape xy
Set the default command and meta characters. See section Command Character.
defflow fstate
Select default flow control behavior. See section Flow.
defgr state
Select default GR processing behavior. See section Character Processing.
defhstatus [status]
Select default window hardstatus line. See section Hardstatus.
defkanji wtype
Select default GR processing behavior. See section Character Processing.
deflogin state
Select default utmp logging behavior. See section Login.
defmode mode
Select default file mode for ptys. See section Mode.
defmonitor state
Select default activity monitoring behavior. See section Monitoring.
defobuflimit limit
Select default output buffer limit. See section Obuflimit.
defscrollback num
Set default lines of scrollback. See section Scrollback.
defwrap state
Set default line-wrapping behavior. See section Wrap.
defwritelock on|off|auto
Set default writelock behavior. See section Multiuser.
defzombie [keys]
Keep dead windows. See section Zombie.
Disconnect screen from the terminal. See section Detach.
Enter digraph sequence. See section Digraph.
Write the window's termcap entry to a file. See section Write out the window's termcap entry.
echo [-n] message
Display a message on startup. See section Startup.
escape xy
Set the command and meta characters. See section Command Character.
exec [[fdpat] command [args ...]]
Run a subprocess (filter). See section Exec.
flow [fstate]
Set flow control behavior. See section Flow.
gr [state]
Change GR charset processing. See section Character Processing.
Write out the contents of the current window. See section hardcopy.
hardcopy_append state
Append to hardcopy files. See section hardcopy.
hardcopydir directory
Place, where to dump hardcopy files. See section hardcopy.
hardstatus [state]
Use the hardware status line. See section Hardware Status Line.
height [lines]
Set display height. See section Window Size.
Display current key bindings. See section Help.
Find previous command beginning .... See section History.
Display terminal settings. See section Info.
ins_reg [key]
Removed, use paste instead. See section Registers.
kanji wtype [dtype]
Set the kanji type of a window. See section Character Processing.
Destroy the current window. See section Kill.
Redisplay the last message. See section Display Last Message.
Display licensing information. See section Startup.
Lock the controlling terminal. See section Lock.
log [state]
Log all output in the current window. See section log.
logfile filename
Place where to collect logfiles. See section log.
login [state]
Log the window in `/etc/utmp'. See section Login.
Use only the default mapping table for the next keystroke. See section Bindkey Control.
Don't try to do keymapping on the next keystroke. See section Bindkey Control.
maptimeout timo
Set the intercharacter timeout used for keymapping. See section Bindkey Control.
markkeys string
Rebind keys in copy mode. See section markkeys.
Insert the command character. See section Command Character.
monitor [state]
Monitor activity in window. See section Monitoring.
msgminwait sec
Set minimum message wait. See section Message Wait.
msgwait sec
Set default message wait. See section Message Wait.
multiuser state
Go into single or multi user mode. See section Multiuser Session.
nethack state
Use nethack-like error messages. See section Nethack.
Switch to the next window. See section Selecting a Window.
number [n]
Change/display the current window's number. See section Number.
obuflimit [limit]
Select output buffer limit. See section Obuflimit.
Switch to the window you were in last. See section Selecting a Window.
partial state
Set window to partial refresh. See section Redisplay.
password [crypted_pw]
Set reattach password. See section Detach.
paste [src_regs [dest_reg]]
Paste contents of paste buffer or registers somewhere. See section Paste.
pastefont [state]
Include font information in the paste buffer. See section Paste.
Close and Reopen the window's terminal. See section Break.
Detach and hang up. See section Power Detach.
pow_detach_msg [message]
Set message displayed on pow_detach. See section Power Detach.
Switch to the previous window. See section Selecting a Window.
printcmd [cmd]
Set a command for VT100 printer port emulation. See section Printcmd.
process [key]
Treat a register as input to screen. See section Registers.
Kill all windows and exit. See section Quit.
Read the paste buffer from the screen-exchange file. See section Screen-Exchange.
readreg [reg [file]]
Load a register from paste buffer or file. See section Registers.
Redisplay the current window. See section Redisplay.
register key string
Store a string to a register. See section Registers.
Delete the screen-exchange file. See section Screen-Exchange.
Reset the terminal settings for the window. See section Reset.
screen [opts] [n] [cmd [args]]
Create a new window. See section Screen Command.
scrollback num
Set size of scrollback buffer. See section Scrollback.
select [n]
Switch to a specified window. See section Selecting a Window.
sessionname [name]
Name this session. See section Session Name.
setenv [var [string]]
Set an environment variable for new windows. See section Setenv.
shell command
Set the default program for new windows. See section Shell.
shelltitle title
Set the default name for new windows. See section Shell.
silence [state|seconds]
Monitor a window for inactivity. See section Silence.
silencewait seconds
Default timeout to trigger an inactivity notify. See section Silence.
sleep num
Pause during startup. See section Startup.
slowpaste msec
Slow down pasting in windows. See section Paste.
sorendition [attr [color]]
Change text highlighting. See section Sorendition.
startup_message state
Display copyright notice on startup. See section Startup.
stuff string
Stuff a string in the input buffer of a window. See section Paste.
Put session in background. See section Suspend.
term term
Set $TERM for new windows. See section Term.
termcap term terminal-tweaks [window-tweaks]
Tweak termcap entries for best performance. See section The termcap command.
terminfo term terminal-tweaks [window-tweaks]
Ditto, for terminfo systems. See section The termcap command.
termcapinfo term terminal-tweaks [window-tweaks]
Ditto, for both systems. See section The termcap command.
Display time and load average. See section Time.
title [windowtitle]
Set the name of the current window. See section Title Command.
unsetenv var
Unset environment variable for new windows. See section Setenv.
vbell [state]
Use visual bell. See section Bell.
vbell_msg [message]
Set vbell message. See section Bell.
vbellwait sec
Set delay for vbell message. See section Bell.
Display screen version. See section Version.
wall message
Write a message to all displays. See section Multiuser Session.
width [num]
Set the width of the window. See section Window Size.
List active windows. See section Windows.
wrap [state]
Control line-wrap behavior. See section Wrap.
Write paste buffer to screen-exchange file. See section Screen-Exchange.
writelock on|off|auto
Grant exclusive write permission. See section Multiuser Session.
Send an XOFF character. See section XON and XOFF.
Send an XON character. See section XON and XOFF.
zombie [keys]
Keep dead windows. See section Zombie.

New Window

This section describes the commands for creating a new window for running programs. When a new window is created, the first available number from the range 0...9 is assigned to it. There can be no more than 10 windows active at any one time unless screen was compiled with a higher MAXWIN setting.


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

Screen Command

Command: screen [opts] [n] [cmd [args]]
(C-a c, C-a C-c)
Establish a new window. The flow-control options (`-f', `-fn' and `-fa'), title option (`-t'), login options (`-l' and `-ln') , terminal type option (`-T term') and scrollback option (`-h num') may be specified for each command. If an optional number n in the range 0...9 is given, the window number n is assigned to the newly created window (or, if this number is already in-use, the next available number). If a command is specified after screen, this command (with the given arguments) is started in the window; otherwise, a shell is created.

If a tty (character special device) name (e.g. `/dev/ttyS0') is specified as cmd, then the window is directly connected to this device. This is similar to the cmd `kermit -l /dev/ttyS0 -c' but saves resources and is more efficient.

Thus, if your `.screenrc' contains the lines

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

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


Command: 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.

Command: unsetenv var
Unset an environment variable.


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

Command: shelltitle title
Set the title for all shells created during startup or by the C-a C-c command. See section Naming Windows (Titles), for details about what titles are.


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

Selecting a Window

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

Moving Back and Forth

Command: next
(C-a SPC, C-a n, C-a C-n)
Switch to the next window. This command can be used repeatedly to cycle through the list of windows. (On some terminals, C-SPC generates a NUL character, so you must release the control key before pressing space.)

Command: prev
(C-a p, C-a C-p)
Switch to the previous window (the opposite of C-a n).

Other Window

Command: other
(C-a C-a)
Switch to the last window displayed. Note that this command defaults to the command character typed twice, unless overridden. For instance, if you use the option `-e]x', this command becomes ]] (see section Command Character).


Command: select [n]
(C-a n, C-a ', C-a ")
Switch to the window with the number n. If no window number is specified, you get prompted for an identifier. This can be a window name (title) or a number. When a new window is established, the lowest available number is assigned to this window. Thus, the first window can be activated by select 0; there can be no more than 10 windows present simultaneously (unless screen is compiled with a higher MAXWIN setting).

Session Management Commands

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


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

Command: detach
(C-a d, C-a C-d)
Detach the screen session (disconnect it from the terminal and put it into the background). A detached screen can be resumed by invoking screen with the -r option. (see section Invoking Screen)

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 session. This is useful, if you have privileged programs running under screen and you want to protect your session from reattach attempts by users that managed to assume your uid. (I.e. any superuser.) If no crypted password is specified, screen prompts twice a password and places its encryption in the paste buffer. Default is `none', which disables password checking.

Power Detach

Command: pow_detach
(C-a D)
Mainly the same as detach, but also sends a HANGUP signal to the parent process of screen.
Caution: This will result in a logout if screen was started from your login shell.

Command: pow_detach_msg [message]
The message specified here is output whenever a power detach is performed. It may be used as a replacement for a logout message or to reset baud rate, etc. Without parameter, the current message is shown.


Command: lockscreen
(C-a x, C-a C-x)
Call a screenlock program (`/local/bin/lck' or `/usr/bin/lock' or a builtin, if no other is available). Screen does not accept any command keys until this program terminates. Meanwhile processes in the windows may continue, as the windows are in the detached state. The screenlock program may be changed through the environment variable $LOCKPRG (which must be set in the shell from which screen is started) and is executed with the user's uid and gid.

Warning: When you leave other shells unlocked and 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.

Multiuser Session

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


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


Command: acladd usernames
Enable users to fully access this screen session. Usernames can be one user or a comma seperated list of users. This command enables to attach to the screen session and performs the equivalent of aclchg usernames +rwx "#?". To add a user with restricted access, use the aclchg command below. Multi-user mode only.


Command: aclchg usernames permbits list
Change permissions for a comma seperated list of users. Permission bits are represented as `r', `w' and `x'. Prefixing `+' grants the permission, `-' removes it. The third parameter is a comma seperated list of commands 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 is 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 e.g. window 2: `aclchg username -w+w 2'. To allow readonly access to the session: `aclchg username -w "#"'. As soon as a user's name is known to screen, he can attach to the session and (per default) has full permissions for all command and windows. Execution permission for the acl commands, at and others should also be removed or the user may be able to regain write permission. Multi-user mode only.


Command: 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.


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


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

Command: defwritelock on|off|auto
Sets the default writelock behaviour for new windows. Initially all windows will be created with automatic writelocks.

Session Name

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


Command: suspend
(C-a z, C-a C-z)
Suspend screen. The windows are in the detached state while screen is suspended. This feature relies on the parent shell being able to do job control.


Command: quit
(C-a C-\)
Kill all windows and terminate screen. Note that on VT100-style terminals the keys C-4 and C-\ are identical. So be careful not to type C-a C-4 when selecting window no. 4. Use the empty bind command (as in bind "^\") to remove a key binding (see section Key Binding).

Window Settings

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

Naming Windows (Titles)

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

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

Title Command

Command: title [windowtitle]
(C-a A)
Set the name of the current window to windowalias. If no name is specified, screen prompts for one.

Dynamic Titles

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

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

Setting up your prompt for shell titles

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

set prompt='<ESC>[0000m<ESC>k<ESC>\% '

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.

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

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

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

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

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

Setting up shell titles in your `.screenrc'

Here are some .screenrc examples:

screen -t top 2 nice top

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

shelltitle '> |csh'
screen 1

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

/usr/joe/src/dir> trn

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

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

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

% !em
emacs file.c

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

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

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


Command: console [state]
Grabs or ungrabs the machines console output to a window. When the argument is omitted the current state is displayed. Note: Only the owner of `/dev/console' can grab the console output. This command is only available if the host supports the ioctl TIOCCONS.


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


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

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


Command: defmode mode
The mode of each newly allocated pseudo-tty is set to mode. mode is an octal number as used by chmod(1). Defaults to 0622 for windows which are logged in, 0600 for others (e.g. when -ln was specified for creation. See section Screen Command).


Command: 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 redefined by means of the activity command. Each occurrence of `%' in message is replaced by the number of the window in which activity has occurred, and each occurrence of `~' is replaced by the definition for bell in your termcap (usually an audible bell). The default message is

'Activity in window %'

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

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

Command: monitor [state]
(C-a M)
Toggles monitoring of the current window. When monitoring is turned on and the affected window is switched into the background, the activity notification message will be displayed in the status line at the first sign of output, and the window will also be marked with an `@' in the window-status display (see section Windows). Monitoring defaults to `off' for all windows.


Command: windows
(C-a w, C-a C-w)
Uses the message line to display a list of all the windows. Each window is listed by number with the name of the program running in the window (or its title); the current window is marked with a `*'; the previous window is marked with a `-'; all the windows that are logged in are marked with a `$' (see section Login); a background window that has received a bell is marked with a `!'; a background window that is being monitored and has had activity occur is marked with an `@' (see section Monitoring); a window which has output logging turned on is marked with `(L)'; windows occupied by other users are marked with `&'; windows in the zombie state are marked with `Z'. If this list is too long to fit on the terminal's status line only the portion around the current window is displayed.


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.

Command: defhstatus
The hardstatus line that all new windows will get is set to status. This command is useful to make the hardstatus of every window display the window number or title or the like. status may contain the same directives as in the window messages, but the directive escape character is `^E' (octal 005) instead of `%'. This was done to make a misinterpretion 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.

Virtual Terminal

Each window in a screen session emulates a VT100 terminal, with some extra functions added. The VT100 emulator is hardcoded, no other terminal types can be emulated. The commands described here modify the terminal emulation.

Control Sequences

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

ESC E                           Next Line
ESC D                           Index
ESC M                           Reverse Index
ESC H                           Horizontal Tab Set
ESC Z                           Send VT100 Identification String
ESC 7                   (V)     Save Cursor and Attributes
ESC 8                   (V)     Restore Cursor and Attributes
ESC [s                  (A)     Save Cursor and Attributes
ESC [u                  (A)     Restore Cursor and Attributes
ESC c                           Reset to Initial State
ESC 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                           Title 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 ]                   (A)     Operating System Command (Hardstatus, xterm
                                title hack)
Control-N               (A)     Lock Shift G1 (SO)
Control-O               (A)     Lock Shift G0 (SI)
ESC n                   (A)     Lock Shift G2
ESC o                   (A)     Lock Shift G3
ESC N                   (A)     Single Shift G2
ESC O                   (A)     Single Shift G3
ESC ( Pcs               (A)     Designate character set as G0
ESC ) Pcs               (A)     Designate character set as G1
ESC * Pcs               (A)     Designate character set as G2
ESC + Pcs               (A)     Designate character set as G3
ESC [ Pn ; Pn H                 Direct Cursor Addressing
ESC [ Pn ; Pn f                 Direct Cursor Addressing
ESC [ Pn J                      Erase in Display
      Pn = None or 0            From Cursor to End of Screen
           1                    From Beginning of Screen to Cursor
           2                    Entire Screen
ESC [ Pn K                      Erase in Line
      Pn = None or 0            From Cursor to End of Line
           1                    From Beginning of Line to Cursor
           2                    Entire Line
ESC [ Pn A                      Cursor Up
ESC [ Pn B                      Cursor Down
ESC [ Pn C                      Cursor Right
ESC [ Pn D                      Cursor Left
ESC [ Ps ;...; Ps m             Select Graphic Rendition
      Ps = None or 0            Default Rendition
           1                    Bold
           2            (A)     Faint
           3            (A)     Standout Mode (ANSI: Italicized)
           4                    Underlined
           5                    Blinking
           7                    Negative Image
           22           (A)     Normal Intensity
           23           (A)     Standout Mode off (ANSI: Italicized off)
           24           (A)     Not Underlined
           25           (A)     Not Blinking
           27           (A)     Positive Image
           30           (A)     Foreground Black
           31           (A)     Foreground Red
           32           (A)     Foreground Green
           33           (A)     Foreground Yellow
           34           (A)     Foreground Blue
           35           (A)     Foreground Magenta
           36           (A)     Foreground Cyan
           37           (A)     Foreground White
           39           (A)     Foreground Default
           40           (A)     Background Black
	   ...                  ...
	   49           (A)     Background Default
ESC [ Pn g                      Tab Clear
      Pn = None or 0            Clear Tab at Current Position
           3                    Clear All Tabs
ESC [ Pn ; Pn r         (V)     Set Scrolling Region
ESC [ Pn I              (A)     Horizontal Tab
ESC [ Pn Z              (A)     Backward Tab
ESC [ Pn L              (A)     Insert Line
ESC [ Pn M              (A)     Delete Line
ESC [ Pn @              (A)     Insert Character
ESC [ Pn P              (A)     Delete Character
ESC [ Pn S                      Scroll Scrolling Region Up
ESC [ Pn T                      Scroll Scrolling Region Down
ESC [ Ps ;...; Ps h             Set Mode
ESC [ Ps ;...; Ps l             Reset Mode
      Ps = 4            (A)     Insert Mode
           20           (A)     `Automatic Linefeed' Mode.
           34                   Normal Cursor Visibility
           ?1           (V)     Application Cursor Keys
           ?3           (V)     Change Terminal Width to 132 columns
           ?5           (V)     Reverse Video
           ?6           (V)     `Origin' Mode
           ?7           (V)     `Wrap' Mode
           ?25          (V)     Visible Cursor
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                 (V)     Send Terminal Parameter Report
ESC [ > c                       Send 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, see section Paste). 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 section Bindkey for further details on the syntax and examples.

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

Key name        Termcap name    Command
Cursor up            ku         stuff \033[A
                                stuff \033OA      (A)
Cursor down          kd         stuff \033[B
                                stuff \033OB      (A)
Cursor right         kr         stuff \033[C
                                stuff \033OC      (A)
Cursor left          kl         stuff \033[D
                                stuff \033OD      (A)
Function key 0       k0         stuff \033[10~
Function key 1       k1         stuff \033OP
Function key 2       k2         stuff \033OQ
Function key 3       k3         stuff \033OR
Function key 4       k4         stuff \033OS
Function key 5       k5         stuff \033[15~
Function key 6       k6         stuff \033[17~
Function key 7       k7         stuff \033[18~
Function key 8       k8         stuff \033[19~
Function key 9       k9         stuff \033[20~
Function key 10      k;         stuff \033[21~
Function key 11      F1         stuff \033[22~
Function key 12      F2         stuff \033[23~
Backspace            kb         stuff \010
Home                 kh         stuff \033[1~
End                  kH         stuff \033[4~
Insert               kI         stuff \033[2~
Delete               kD         stuff \033[3~
Page up              kP         stuff \033[5~
Page down            kN         stuff \033[6~
Keypad 0             f0         stuff 0
                                stuff \033Op      (A)
Keypad 1             f1         stuff 1
                                stuff \033Oq      (A)
Keypad 2             f2         stuff 2
                                stuff \033Or      (A)
Keypad 3             f3         stuff 3
                                stuff \033Os      (A)
Keypad 4             f4         stuff 4
                                stuff \033Ot      (A)
Keypad 5             f5         stuff 5
                                stuff \033Ou      (A)
Keypad 6             f6         stuff 6
                                stuff \033Ov      (A)
Keypad 7             f7         stuff 7
                                stuff \033Ow      (A)
Keypad 8             f8         stuff 8
                                stuff \033Ox      (A)
Keypad 9             f9         stuff 9
                                stuff \033Oy      (A)
Keypad +             f+         stuff +
                                stuff \033Ok      (A)
Keypad -             f-         stuff -
                                stuff \033Om      (A)
Keypad *             f*         stuff *
                                stuff \033Oj      (A)
Keypad /             f/         stuff /
                                stuff \033Oo      (A)
Keypad =             fq         stuff =
                                stuff \033OX      (A)
Keypad .             f.         stuff .
                                stuff \033On      (A)
Keypad ,             f,         stuff ,
                                stuff \033Ol      (A)
Keypad enter         fe         stuff \015
                                stuff \033OM      (A)


Command: digraph [preset]
This command prompts the user for a digraph sequence. The next two characters typed are looked up in a builtin table and the resulting character is inserted in the input stream. For example, if the user enters `a"', an a-umlaut will be inserted. If the first character entered is a 0 (zero), screen will treat the following charcters (up to three) as an octal number instead. The optional argument preset is treated as user input, thus one can create an "umlaut" key. For example the command `bindkey ^K digraph '"'' enables the user to generate an a-umlaut by typing `CTRL-K a'.


Command: 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 means of the bell command. Each occurrence of `%' in message is replaced by the number of the window to which a bell has been sent, and each occurrence of `~' is replaced by the definition for bell in your termcap (usually an audible bell). The default message is

'Bell in window %'

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

Command: vbell [state]
(C-a C-g)
Sets or toggles the visual bell setting for the current window. If vbell is switched to `on', but your terminal does not support a visual bell, the visual bell message is displayed in the status line when the bell character is received. Visual bell support of a terminal is defined by the termcap variable vb. See section `Visual Bell' in The Termcap Manual, for more information on visual bells. The equivalent terminfo capability is flash.

Per default, vbell is `off', thus the audible bell is used.

Command: 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' and the terminal does not support a visual bell. The default message is `Wuff, Wuff!!'. Without parameter, the current message is shown.

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


Command: clear
(C-a C)
Clears the screen and saves its contents to the scrollback buffer.


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


Command: allpartial state
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 behaviour of newly created windows.

Command: partial state
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.

Command: redisplay
(C-a l, C-a C-l)
Redisplay the current window. Needed to get a full redisplay in partial redraw mode.


Command: wrap state
(C-a r, C-a C-r)
Sets the line-wrap setting for the current window. When line-wrap is on, the second consecutive printable character output at the last column of a line will wrap to the start of the following line. As an added feature, backspace (^H) will also wrap through the left margin to the previous line. Default is `on'.

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


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

Window Size

Command: width [num]
(C-a W)
Toggle the window width between 80 and 132 columns, or set it to num columns if an argument is specified. This requires a capable terminal and the termcap entries `Z0' and `Z1'. See the termcap command (see section Termcap), for more information.

Command: height [lines]
Set the display height to a specified number of lines. When no argument is given it toggles between 24 and 42 lines display.

Character Processing

Command: c1 [state]
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.

Command: gr [state]
Turn GR charset switching on/off. Whenever screens sees an input char with an 8th bit set, it will use the charset stored in the GR slot and print the character with the 8th bit stripped. The default (see also `defgr') is not to process GR switching because otherwise the ISO88591 charset would not work.

Command: kanji wtype [dtype]
Tell screen how to process kanji input/output. wtype and dtype must be one of the strings `jis', `euc' or `sjis'. The first argument sets the kanji type of the current window. Each window can emulate a different type. The optional second parameter tells screen how to write the kanji codes to the connected terminal. The preferred method of setting the display type is to use the `KJ' termcap entry. See section Special Terminal Capabilities. See also `defkanji', which changes the default setting of a new window.

Command: charset set
Change the current character set slot designation and charset mapping. The first four character of set are treated as charset designators while the fifth and sixth character must be in range `0' to `3' and set the GL/GR charset mapping. On every position a `.' may be used to indicate that the corresponding charset/mapping should not be changed (set is padded to six characters internally by appending `.' chars). New windows have `BBBB02' as default charset, unless a `kanji' command is active.

The current setting can be viewed with the See section Info command.

Command: defc1 state
Same as the `c1' command except that the default setting for new windows is changed. Initial setting is `on'.

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

Command: defkanji wtype
Same as the `kanji' command except that the default setting for new windows is changed. Initial setting is `off', i.e. `jis'.

Command: defcharset [set]
Like the `charset' command except that the default setting for new windows is changed. Shows current default if called without argument.

Copy and Paste

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


Command: copy
(C-a [, C-a C-[, C-a ESC)
Enter copy/scrollback mode. This allows you to copy text from the current window and its history into the paste buffer. In this mode a vi-like full screen editor is active, with controls as outlined below.


Command: crlf [state]
This affects the copying of text regions with the C-a [ command. If it is set to `on', lines will be separated by the two character sequence `CR'/`LF'. Otherwise only `LF' is used. crlf is off by default. When no parameter is given, the state is toggled.


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

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


Command: 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 command markkeys h=^B:l=^F:$=^E would set some keys to be more familiar to emacs users. If your terminal sends characters, that cause you to abort copy mode, then this command may help by binding these characters to do nothing. The no-op character is `' and is used like this: markkeys @=L=H if you do not want to use the `H' or `L' commands any longer. As shown in this example, multiple keys can be assigned to one function in a single statement.

Movement Keys

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

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

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

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

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

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

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

g moves to the beginning of the buffer.

% jumps to the specified percentage of the buffer.

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


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

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

W marks exactly one word.

Repeat Count

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


/ vi-like search forward.

? vi-like search backward.

C-a s emacs style incremental search forward.

C-r emacs style reverse i-search.


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

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

This moves one to the middle line of the screen, moves in 20 columns left, marks the beginning of the 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 3 modes: lines separated by a newline character (012), lines glued seamless, or lines separated by a single space. Note that you can prepend the newline character with a carriage return character, by issuing a set crlf on.

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

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

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

> sets the (second) mark and writes the contents of the paste buffer to the screen-exchange file (`/tmp/screen-exchange' per default) once copy-mode is finished. See section Screen-Exchange.
This example demonstrates how to dump the whole scrollback buffer to that file:
C-a [ g SPACE G $ >.

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

x exchanges the first mark and the current cursor position. You can use this to adjust an already placed mark.

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

All keys not described here exit copy mode.


Command: paste [registers [destination]]
(C-a ], C-a C-])
Write the (concatenated) contents of the specified registers to the stdin stream of the current window. The register `.' is treated as the paste buffer. If no parameter is specified the user is prompted to enter a single register. The paste buffer can be filled with the copy, history and readbuf commands. Other registers can be filled with the register, readreg and paste commands. If paste is called with a second argument, the contents of the specified registers is pasted into the named destination register rather than the window. If `.' is used as the second argument, the display's paste buffer is the destination. Note, that paste uses a wide variety of resources: Usually both, a current window and a current display are required. But whenever a second argument is specified no current window is needed. When the source specification only contains registers (not the paste buffer) then there need not be a current display (terminal attached), as the registers are a global resource. The paste buffer exists once for every user.

Command: pastefont [state]
Tell screen to include font information in the paste buffer. The default is not to do so. This command is especially usefull for multi character fonts like kanji.

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

Command: readreg [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. The following example will paste the system's password file into the screen window (using register p, where a copy remains):

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


Command: copy_reg [key]
Removed. Use readreg instead.

Command: ins_reg [key]
Removed. Use paste instead.

Command: process [key]
Stuff the contents of the specified register into the screen input queue. If no argument is given you are prompted for a register name. The text is parsed as if it had been typed in from the user's keyboard. This command can be used to bind multiple actions to a single key.

Command: register key string
Save the specified string to the register key.

Command: 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. You cannot paste large buffers with the stuff command. It is most useful for key bindings. See section Bindkey


Command: bufferfile [exchange-file]
Change the filename used for reading and writing with the paste buffer. If the exchange-file parameter is omitted, screen reverts to the default of `/tmp/screen-exchange'. The following example will paste the system's password file into the screen window (using the paste buffer, where a copy remains):

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

Command: readbuf
(C-a <)
Reads the contents of the current screen-exchange file into the paste buffer.

Command: removebuf
(C-a =)
Unlinks the screen-exchange file.

Command: writebuf
(C-a >)
Writes the contents of the paste buffer to a public accessible screen-exchange file. This is thought of as a primitive means of communication between screen users on the same host. See also C-a ESC (see section Copying).


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

Subprocess Execution

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


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 newcommand's stdin/stdout/stderr, the process already running (shell) and screen itself (window) is controlled by the filedescriptor pattern fdpat. This pattern is basically a three character sequence representing stdin, stdout and stderr of newcommand. A dot (.) connects the file descriptor to screen. An exclamation mark (!) causes the file descriptor to be connected to the already running process. A colon (:) combines both.
User input will go to newcommand unless newcommand requests the old process' output (fdpats first character is `!' or `:') or a pipe symbol (`|') is added to the end of fdpat.
Invoking exec without arguments shows name and arguments of the currently running subprocess in this window.
When a subprocess is running the kill command will affect it instead of the window's process.
Refer to the postscript file `doc/' for a confusing illustration of all 21 possible combinations. Each drawing shows the digits 2, 1, 0 representing the three file descriptors of newcommand. The box marked `W' is usual pty that has the application-process on its slave side. The box marked `P' is the secondary pty that now has screen at its master side.

Using Exec



exec /bin/sh
exec ... /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'.
!!stty 19200
exec!stty 19200
exec !.. stty 19200
Set the speed of the window's tty. If your stty command operates on stdout, then add another `!'. This is a useful command, when a screen window is directly connected to a serial line that needs to be configured.
exec !..| less
This adds a pager to the window output. The special character `|' is needed to give the user control over the pager although it gets its input from the 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.

Key Binding

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

The bind command

Command: bind key [command [args]]
Bind a command to a key. The key argument is either a single character, a two-character sequence of the form `^x' (meaning C-x), a backslash followed by an octal number (specifying the ASCII code of the character), or a backslash followed by a second character, such as `\^' or `\\'. The argument can also be quoted, if you like. If no further argument is given, any previously established binding for this key is removed. The command argument can be any command (see section Command Index).

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

Examples of the bind command

Some examples:

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

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

Command Character

Command: escape xy
Set the command character to x and the character generating a literal command character to y (just like with the `-e' option). Each argument is either a single character, a two-character sequence of the form `^x' (meaning C-x), a backslash followed by an octal number (specifying the ASCII code of the character), or a backslash followed by a second character, such as `\^' or `\\'. The default is `^Aa', but `"' is recommended by one of the authors.

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

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

Command: command
This command has the same effect as typing the screen escape character (C-a). It is probably only useful for key bindings. See section Bindkey.


Command: help
(C-a ?)
Displays a help screen showing you all the key bindings. The first pages list all the internal commands followed by their bindings. Subsequent pages will display the custom commands, one command per key. Press space when you're done reading each page, or return to exit early. All other characters are ignored. See section Default Key Bindings.


Command: bindkey [opts] [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 tring 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 intercharacter timing. One cannot turn off the timing if a termcap capabilty is used.

`cmd' can be any of screen's commands with an arbitrary number of `args'. If `cmd' is omitted the keybinding is removed from the table.

Bindkey Examples

Here are some examples of keyboard bindings:

bindkey -d

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

bindkey -k k1 select 1

Make the "F1" key switch to window one.

bindkey -t foo stuff barfoo

Make `foo' an abrevation of the word `barfoo'. Timeout is disabled so that users can type slowly.

bindkey "\024" mapdefault

This keybinding makes `C-t' an escape character for keybindings. If you did the above `stuff barfoo' binding, you can enter the word `foo' by typing `C-t foo'. If you want to insert a `C-t' you have to press the key twice (i.e. escape the escape binding).

bindkey -k F1 command

Make the F11 (not F1!) key an alternative screen escape (besides `C-a').

Bindkey Control

Command: mapdefault
Tell screen that the next input character should only be looked up in the default bindkey table.
Command: mapnotnext
Like mapdefault, but don't even look in the default bindkey table.
Command: maptimeout timo
Set the intercharacter timer for input sequence detection to a timeout of timo ms. The default timeout is 300ms. Maptimeout with no arguments shows the current setting.

Flow Control

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

About screen flow control settings

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

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

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

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


Command: defflow fstate [interrupt]
Same as the flow command except that the default setting for new windows is changed. Initial setting is `auto'. Specifying flow auto interrupt has the same effect as the command-line options `-fa' and `-i'. Note that if `interrupt' is enabled, all existing displays are changed immediately to forward interrupt signals.

Command: flow [fstate]
(C-a f, C-a C-f)
Sets the flow-control mode for this window to fstate, which can be `on', `off' or `auto'. Without parameters it cycles the current window's flow-control setting. Default is set by `defflow'.


Command: xon
(C-a q, C-a C-q)
Send a ^Q (ASCII XON) to the program in the current window. Redundant if flow control is set to `off' or `auto'.

Command: xoff
(C-a s, C-a C-s)
Send a ^S (ASCII XOFF) to the program in the current window.


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

Choosing the termcap entry for a window

Usually screen tries to emulate as much of the VT100/ANSI standard as possible. But if your terminal lacks certain capabilities the emulation may not be complete. In these cases screen has to tell the applications that some of the features are missing. This is no problem on machines using termcap, because screen can use the $TERMCAP variable to customize the standard screen termcap.

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

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

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

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

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

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

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

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

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

Write out the window's termcap entry

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

The termcap command

Command: termcap term terminal-tweaks [window-tweaks]
Command: terminfo term terminal-tweaks [window-tweaks]
Command: termcapinfo term terminal-tweaks [window-tweaks]
Use this command to modify your terminal's termcap entry without going through all the hassles involved in creating a custom termcap entry. Plus, you can optionally customize the termcap generated for the windows. You have to place these commands in one of the screenrc starup files, as they are meaningless once the terminal emulator is booted.

If your system uses the terminfo database rather than termcap, screen will understand the terminfo command which has the same effects as the termcap command. Two separate commands are provided, as there are subtle syntactic differences, e.g. when parameter interpolation (using `%') is required. Note that the termcap names of the capabilities have to be used with the terminfo command.

In many cases, where the arguments are valid in both terminfo and termcap syntax, you can use the command termcapinfo, which is just a shorthand for a pair of termcap and terminfo commands with identical arguments.

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

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

Termcap Examples

Some examples:

termcap xterm*  xn:hs@

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

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

Specifies the firm-margined `xn' capability for all terminals that begin with `vt', and the second line will also add the escape-sequences to switch into (Z0) and back out of (Z1) 132-character-per-line mode if this is a VT102 or VT220. (You must specify Z0 and Z1 in your termcap to use the width-changing commands.)

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

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

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

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

If you would like to fully specify each window's termcap entry, you should instead set the $SCREENCAP variable prior to running screen. See section Virtual Terminal, for the details of the screen terminal emulation. See section `Termcap' in The Termcap Manual, for more information on termcap definitions.

Special Terminal Capabilities

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

Terminal has VT100 style margins (`magic margins'). Note that this capability is obsolete -- screen now uses the standard `xn' instead.
Change width to 132 columns.
Change width to 80 columns.
Resize display. This capability has the desired width and height as arguments. SunView(tm) example: `\E[8;%d;%dt'.
Terminal doesn't need flow control. Send ^S and ^Q direct to the application. Same as flow off. The opposite of this capability is `nx'.
Terminal can deal with ISO 2022 font selection sequences.
Switch charset `G0' to the specified charset. Default is `\E(%.'.
Switch charset `G0' back to standard charset. Default is `\E(B'.
Use the string as a conversion table for font 0. See the `ac' capability for more details.
Switch cursor keys to application mode.
Switch cursor keys to cursor mode.
Enable autonuke for displays of this terminal type. (see section Autonuke).
Set the output buffer limit. See the `obuflimit' command (see section Obuflimit) for more details.
Set the kanji type of the terminal. Valid strings are `jis', `euc' and `sjis'.
Change character forground color in an ANSI conform way. This capability will almost always be set to `\E[3%dm' (`\E[3%p1%dm' on terminfo machines).
Same as `AF', but change background color.
Does understand ANSI set default fg/bg color (`\E[39m / \E[49m').
Describe a translation of characters to strings depending on the current font. (see section Character Translation).


Command: autonuke state
Sets whether a clear screen sequence should nuke all the output that has not been written to the terminal. See section Obuflimit. This property is set per display, not per window.

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


Command: 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. This property is set per display, not per window.

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

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.


    <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 occurence of `%' in <template> gets substituted with the template-arg specified together with the character. If your strings are not similar at all, then use `%' as a template and place the full string in <template-arg>. A quoting mechanism was added to make it possible to use a real `%'. The `\' character quotes the special characters `\', `%', and `,'.

Here is an example:

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

This tells screen, how to translate ISOlatin1 (charset `B') upper case umlaut characters on a hp700 terminal that has a german charset. `\304' gets translated to `\E(K[\E(B' and so on. Note that this line gets parsed *three* times before the internal lookup table is built, therefore a lot of quoting is needed to create a single `\'.

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

This example shows one use of the extension:

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

Here, a part of the german (`K') charset is emulated on an xterm. If screen has to change to the `K' charset, `\E(B' will be sent to the terminal, i.e. the ASCII charset is used instead. The template is just `%', so the mapping is straightforward: `[' to `\304', `\' to `\326', and `]' to `\334'.

The Message Line

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

Using the message line from your program

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

echo "<ESC>^Hello world from window $WINDOW<ESC>\"

where `<ESC>' is ASCII ESC and `^' is a literal caret or up-arrow.

Hardware Status Line

Command: hardstatus [state]
Toggles the use of the terminal's hardware status line. If `on', screen will use this facility to display one line messages. Otherwise these messages are overlayed in reverse video mode at the display line. Note that the hardstatus feature can only be used if the termcap/terminfo capabilities "hs", "ts", "fs" and "ds" are set properly. Default is `on' whenever the "hs" capability is present.

Display Last Message

Command: lastmsg
(C-a m, C-a C-m)
Repeat the last message displayed in the message line. Useful if you're typing when a message appears, because (unless your terminal has a hardware status line) the message goes away when you press a key.

Message Wait

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

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


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


Command: hardcopy
(C-a h, C-a C-h)
Writes out the current display contents to the file `hardcopy.n' in the window's default directory, where n is the number of the current window. This either appends or overwrites the file if it exists, as determined by the hardcopy_append command.

Command: hardcopy_append state
If set to `on', screen will append to the `hardcopy.n' files created by the command hardcopy; otherwise, these files are overwritten each time.

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


Command: log [state]
(C-a H)
Begins/ends logging of the current window to the file `screenlog.n' in the window's default directory, where n is the number of the current window. This filename can be changed with the `logfile' command. If no parameter is given, the logging state is toggled. The session log is appended to the previous contents of the file if it already exists. The current contents and the contents of the scrollback history are not included in the session log. Default is `off'.

Command: logfile filename
Defines the name the logfiles will get. The default is `screenlog.%n'.


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


Command: echo [-n] message
The echo command may be used to annoy screen users with a 'message of the day'. Typically installed in a global 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.


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

Startup Message

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

Miscellaneous commands

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


Command: at [identifier][#|*|%] command [args]
Execute a command at other displays or windows as if it had been entered there. At changes the context (the `current window' or `current display' setting) of the command. If the first parameter describes a non-unique context, the command will be executed multiple times. If the first parameter is of the form `identifier*' then identifier is matched against user names. The command is executed once for each display of the selected user(s). If the first parameter is of the form `identifier%' identifier is matched against displays. Displays are named after the ttys they attach. The prefix `/dev/' or `/dev/tty' may be omitted from the identifier. If identifier has a # or nothing appended it is matched against window numbers and titles. Omitting an identifier in front of the #, * or % character selects all users, displays or windows because a prefix-match is performed. Note that on the affected display(s) a short message will describe what happened. Caution: Permission is checked for the owners or the affected display(s), not for the initiator of the `at' command.


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

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


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


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


Command: nethack state
Changes the kind of error messages used by screen. When you are familiar with the game nethack, you may enjoy the nethack-style messages which will often blur the facts a little, but are much funnier to read. Anyway, standard messages often tend to be unclear as well.

This option is only available if screen was compiled with the NETHACK flag defined (see section Installation). The default setting is then determined by the presence of the environment variable $NETHACKOPTIONS.


Command: number [n]
(C-a N)
Change the current window's number. If the given number n is already used by another window, both windows exchange their numbers. If no argument is specified, the current window number (and title) is shown.


Command: silence [state|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.

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


Command: time
(C-a t, C-a C-t)
Uses the message line to display the time of day, the host name, and the load averages over 1, 5, and 15 minutes (if this is available on your system). For window-specific information use info (see section Info).


Command: version
(C-a v)
Display the version and modification date in the message line.


Command: zombie [keyx]
Command: defzombie [keyx]
Per default 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 kommand may be used to remove the window. Pressing the first key in the dead window has the same effect. Pressing the second key, however, screen will attempt to resurrect the window. The process that was initially running in the window will be launched again. Calling zombie without parameters will clear the zombie setting, thus making windows disappear when the process terminates.

As the zombie setting is affected 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.


Command: printcmd [cmd]
If cmd is not an empty string, screen will not use the terminal capabilities po/pf for printing 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 an argument 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.


Command: sorendition [attr [color]]
Change the way screen does highlighting for text marking and printing messages. attr is a hexadecimal number and describes the attributes (inverse, underline, ...) the text will get. color is a 2 digit number and changes the forground/background of the highlighted text. Some knowledge of screen's internal character representation is needed to make the characters appear in the desired way. The default is currently `10 99' (standout, default colors).

Environment Variables

Number of columns on the terminal (overrides termcap entry).
Directory in which to look for .screenrc.
Alternate user screenrc file.
Number of lines on the terminal (overrides termcap entry).
Screen lock program.
Turns on nethack option.
Used for locating programs to run.
For customizing a terminal's TERMCAP value.
Alternate socket directory.
Alternate user screenrc file.
Default shell program for opening windows (default `/bin/sh').
Alternate socket name. If screen is invoked, and the environment variable STY is set, then it creates only a window in the running screen session rather than starting a new session.
Alternate system screenrc file.
Terminal name.
Terminal description.

Files Referenced

Examples in the screen distribution package for private and global initialization files.
screen initialization commands
Read in after /local/etc/screenrc
Socket directories (default)
Alternate socket directories.
`socket directory/.termcap'
Written by the dumptermcap command
`/usr/tmp/screens/screen-exchange or'
screen interprocess communication buffer
Screen images created by the hardcopy command
Output log files created by the log command
`/usr/lib/terminfo/?/* or'
Terminal capability databases
Login records
Program for locking the terminal.



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


     Ken Beal (,
     Rudolf Koenig (,
     Toerless Eckert (,
     Wayne Davison (,
     Patrick Wolfe (, kailand!pat),
     Bart Schaefer (,
     Nathan Glasser (,
     Larry W. Virden (,
     Howard Chu (,
     Tim MacKenzie (,
     Markku Jarvinen (mta@{cc,cs,ee},
     Marc Boucher (marc@CAM.ORG),
     Doug Siebert (,
     Ken Stillson (,
     Ian Frechett (frechett@spot.Colorado.EDU),
     Brian Koehmstedt (,
     Don Smith (,
     Frank van der Linden (,
     Martin Schweikert (,
     David Vrona (,
     E. Tye McQueen (,
     Matthew Green (,
     Christopher Williams (,
     Matt Mosley (,
     Gregory Neil Shapiro (gshapiro@wpi.WPI.EDU),
     Jason Merrill (jason@jarthur.Claremont.EDU).


This manual describes version 3.7.0 of the screen program. Its roots are a merge of a custom version 2.3PR7 by Wayne Davison and several enhancements to Oliver Laumann's version 2.0. Note that all versions numbered 2.x are copyright by Oliver Laumann.

See also See section Availability.


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

Known Bugs

Reporting Bugs

If you find a bug in Screen, please send electronic mail to `', and also to `'. Include the version number of Screen which you are using. Also include in your message the hardware and operating system, the compiler used to compile, a description of the bug behavior, and the conditions that triggered the bug. Please recompile screen with the `-DDEBUG -DTMPTEST' options enabled, reproduce the bug, and have a look at the debug output written to the directory `/tmp/debug'. If necessary quote suspect passages from the debug output and show the contents of your `config.h' if it matters.


Screen is available under the GNU copyleft.

The latest official release of screen available via anonymous ftp from `', `' or any other GNU distribution site. The latest beta testing release of screen is available from ` (', in the directory `pub/utilities/screen'.


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

Socket Directory

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

Compiling Screen

To compile and install screen:

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

sh ./configure

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


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

Concept Index


  • .screenrc
  • a

  • availability
  • b

  • binding
  • bug report
  • bugs
  • c

  • capabilities
  • command line options
  • command summary
  • compiling screen
  • control sequences
  • copy and paste
  • customization
  • e

  • environment
  • f

  • files
  • flow control
  • i

  • input translation
  • installation
  • introduction
  • invoking
  • k

  • key binding
  • m

  • marking
  • message line
  • multiuser session
  • o

  • options
  • overview
  • s

  • screenrc
  • scrollback
  • socket directory
  • t

  • terminal capabilities
  • title
  • Command Index

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


  • acladd
  • aclchg
  • acldel
  • activity
  • allpartial
  • at
  • autodetach
  • autonuke
  • b

  • bell_msg
  • bind
  • bindkey
  • break
  • bufferfile
  • c

  • c1
  • charset
  • chdir
  • clear
  • colon
  • command
  • console
  • copy
  • copy_reg
  • crlf
  • d

  • debug
  • defautonuke
  • defc1
  • defcharset
  • defescape
  • defflow
  • defgr
  • defhstatus
  • defkanji
  • deflogin
  • defmode
  • defmonitor
  • defobuflimit
  • defscrollback
  • defwrap
  • defwritelock
  • defzombie
  • detach
  • digraph
  • dumptermcap
  • e

  • echo
  • escape
  • exec
  • f

  • flow
  • g

  • gr
  • h

  • hardcopy
  • hardcopy_append
  • hardcopydir
  • hardstatus
  • height
  • help
  • history
  • i

  • info
  • ins_reg
  • k

  • kanji
  • kill
  • l

  • lastmsg
  • license
  • lockscreen
  • log
  • logfile
  • login
  • m

  • mapdefault
  • mapnotnext
  • maptimeout
  • markkeys
  • meta
  • monitor
  • msgminwait
  • msgwait
  • multiuser
  • n

  • nethack
  • next
  • number
  • o

  • obuflimit
  • other
  • p

  • partial
  • password
  • paste
  • pastefont
  • pow_break
  • pow_detach
  • pow_detach_msg
  • prev
  • printcmd
  • process
  • q

  • quit
  • r

  • readbuf
  • readreg
  • redisplay
  • register
  • removebuf
  • reset
  • s

  • screen
  • scrollback
  • select
  • sessionname
  • setenv
  • shell
  • shelltitle
  • silence
  • silencewait
  • sleep
  • slowpaste
  • sorendition
  • startup_message
  • stuff
  • suspend
  • t

  • term
  • termcap
  • termcapinfo
  • terminfo
  • time
  • title
  • u

  • unsetenv
  • v

  • vbell
  • vbell_msg
  • vbellwait
  • version
  • w

  • wall
  • width
  • windows
  • wrap
  • writebuf
  • writelock
  • x

  • xoff
  • xon
  • z

  • zombie
  • Keystroke Index

    This is a list of the default key bindings.

    The leading escape character (see section Command Character) has been omitted from the key sequences, since it is the same for all bindings.


  • "
  • '

  • '
  • .

  • .
  • 0

  • 0...9
  • :

  • :
  • <

  • <
  • =

  • =
  • >

  • >
  • ?

  • ?
  • [

  • [
  • ]

  • ]
  • a

  • A
  • a
  • c

  • C
  • c
  • C-[
  • C-\
  • C-]
  • C-a
  • C-c
  • C-d
  • C-f
  • C-g
  • C-h
  • C-i
  • C-k
  • C-l
  • C-m
  • C-n
  • C-p
  • C-q
  • C-r
  • C-s
  • C-t
  • C-v
  • C-w
  • C-x
  • C-z
  • d

  • D
  • d
  • e

  • ESC
  • f

  • f
  • h

  • H
  • h
  • i

  • i
  • k

  • k
  • l

  • L
  • l
  • m

  • M
  • m
  • n

  • N
  • n
  • p

  • p
  • q

  • q
  • r

  • r
  • s

  • s
  • SPC
  • t

  • t
  • v

  • v
  • w

  • W
  • w
  • x

  • x
  • z

  • Z
  • z
  • {

  • {