man screen

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【扫一扫了解最新限行尾号】
复制小程序

http://www.gnu.org/software/screen/manual/screen.html

Screen User's Manual

• Overview: Preliminary information.
• Getting Started: An introduction to screen.
• Invoking Screen: Command line options for screen.
• Customization: The .screenrc file.
• Commands: List all of the commands.
• New Window: Running a program in a new window.
• Selecting: Selecting a window to display.
• Session Management: Suspend/detach, grant access, connect sessions.
• Regions: Split-screen commands.
• Window Settings: Titles, logging, etc.
• Virtual Terminal: Controlling the screen VT100 emulation.
• Copy and Paste: Exchanging text between windows and sessions.
• Subprocess Execution: I/O filtering with exec.
• Key Binding: Binding commands to keys.
• Flow Control: Trap or pass flow control characters.
• Termcap: Tweaking your terminal's termcap entry.
• Message Line: The screen message line.
• Logging: Keeping a record of your session.
• Startup: Functions only useful at screen startup.
• Miscellaneous: Various other commands.
• String Escapes: Inserting current information into strings
• Environment: Environment variables used by screen.
• Files: Files used by screen.
• Credits: Who's who of screen.
• Bugs: What to do if you find a bug.
• Installation: Getting screen running on your system.
• Concept Index: Index of concepts.
• Command Index: Index of all screen commands.
• Keystroke Index: Index of default key bindings.

1 Overview

Screen is a full-screen window manager that multiplexes a physical terminal between several processes, typically interactive shells. Each virtual terminal provides the functions of the DEC VT100 terminal and, in addition, several control functions from the ISO 6429 (ECMA 48, ANSI X3.64) and ISO 2022 standards (e.g. insert/delete line and support for multiple character sets). There is a scrollback history buffer for each virtual terminal and a copy-and-paste mechanism that allows 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 user's terminal.

When a program terminates, screen (per default) kills the window that contained it. If this window was in the foreground, the display switches to the previously displayed window; if none are left, screen exits.

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

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

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

screen emacs prog.c

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

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

2 Getting Started

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

If you're impatient and want to get started without doing a lot more reading, you should remember this one command: C-a ? (see Key Binding). Typing these two characters will display a list of the available screen commands and their bindings. Each keystroke is discussed in the section on keystrokes (see Default Key Bindings). Another section (see Customization) deals with the contents of your .screenrc.

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

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

3 Invoking Screen

Screen has the following command-line options:

‘-a’

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

‘-A’

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

‘-c file’

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

‘-d [pid.sessionname]’‘-D [pid.sessionname]’

Do not start screen, but instead detach a screen session running elsewhere (see Detach). ‘-d’ has the same effect as typing C-a d from the controlling terminal for the session. ‘-D’ is the equivalent to the power detach key. If no session can be detached, this option is ignored. In combination with the -r/-R option more powerful effects can be achieved:

-d -r

Reattach a session and if necessary detach it first. 

-d -R

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

-d -RR

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

-D -r

Reattach a session. If necessary detach and logout remotely first. 

-D -R

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

-D -RR

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

Note: It is 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 ascreen session, this option sets the default command character. In a multiuser session all users added will start off with this command character. But when attaching to an already running session, this option only changes the command character of the attaching user. This option is equivalent to the commands defescape or escape respectively. (see Command Character). 

‘-f’‘-fn’‘-fa’

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

‘-h num’

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

‘-i’

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

‘-l’‘-ln’

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

‘-ls [match]’‘-list [match]’

Do not start screen, but instead print a list of session identification strings (usually of the form pid.tty.host; see Session Name). Sessions marked ‘detached’ can be resumed with screen -r. Those marked ‘attached’ are running and have a controlling terminal. If the session runs in multiuser mode, it is marked ‘multi’. Sessions marked as ‘unreachable’ either live on a different host or are dead. An unreachable session is considered dead, when its name matches either the name of the local host, or the specified parameter, if any. See the -r flag for a description how to construct matches. Sessions marked as ‘dead’ should be thoroughly checked and removed. Ask your system administrator if you are not sure. Remove sessions with the ‘-wipe’ option. 

‘-L’

Tell screen to turn on automatic output logging for the windows. 

‘-m’

Tell screen to ignore the $STY environment variable. When this option is used, a new session will always be created, regardless of whether screen is being called from within another screen session or not. This flag has a special meaning in connection with the ‘-d’ option:

-d -m

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

-D -m

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

‘-p name_or_number’

Preselect a window. This is useful when you want to reattach to a specific window or you want to send a command via the ‘-X’ option to a specific window. As with screen's select command, ‘-’ selects the blank window. As a special case for reattach, ‘=’ brings up the windowlist on the blank window. 

‘-q’

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

‘-r [pid.sessionname]’‘-r sessionowner/[pid.sessionname]’

Resume a detached screen session. No other options (except combinations with ‘-d’ or ‘-D’) may be specified, though the session name (see Session Name) may be needed to distinguish between multiple detached screensessions. The second form is used to connect to another user's screen session which runs in multiuser mode. This indicates that screen should look for sessions in another user's directory. This requires setuid-root. 

‘-R’

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 (actually screen uses ‘-xRR’ in that case). For combinations with the ‘-D’/‘-d’ option see there. 

‘-s program’

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

‘-S sessionname’

Set the name of the new session to sessionname. This option can be used to specify a meaningful name for the session in place of the default tty.host suffix. This name identifies the session for the screen -list and screen -rcommands. This option is equivalent to the sessionname command (see Session Name). 

‘-t name’

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

‘-U’

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

‘-v’

Print the version number. 

‘-wipe [match]’

List available screens like screen -ls, but remove destroyed sessions instead of marking them as ‘dead’. An unreachable session is considered dead, when its name matches either the name of the local host, or the explicitly given parameter, if any. See the -r flag for a description how to construct matches. 

‘-x’

Attach to a session which is already attached elsewhere (multi-display mode). Screen refuses to attach from within itself. But when cascading multiple screens, loops are not detected; take care. 

‘-X’

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

4 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.

• Startup Files: The .screenrc file.
• Source: Read commands from a file.
• Colon: Entering customization commands interactively.

4.1 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 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.

4.2 Source

4.3 Colon

Customization can also be done online, with this command:

5 Commands

A command in screen can either be bound to a key, invoked from a screenrc file, or called from the colon prompt (see Customization). As of version 3.3, all commands can be bound to keys, although some may be less useful than others. 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] ...

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

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

• Default Key Bindings: screen keyboard commands.
• Command Summary: List of all commands.

5.1 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 '

(select)
Prompt for a window identifier and switch. See Selecting. 

C-a "

(windowlist -b)
Present a list of all windows for selection. See Selecting. 

C-a 0...9, -

(select 0...select 9, select -)
Switch to window number 0...9, or the blank window. See Selecting. 

C-a <Tab>

(focus)
Switch the input focus to the next region. See Regions. 

C-a C-a

(other)
Toggle to the window displayed previously. If this window does no longer exist, other has the same effect as next. See Selecting. 

C-a a

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

C-a A

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

C-a bC-a C-b

(break)
Send a break to the tty. See Break. 

C-a B

(pow_break)
Close and reopen the tty-line. See Break. 

C-a cC-a C-c

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

C-a C

(clear)
Clear the screen. See Clear. 

C-a dC-a C-d

(detach)
Detach screen from this terminal. See Detach. 

C-a D D

(pow_detach)
Detach and logout. See Power Detach. 

C-a fC-a C-f

(flow)
Cycle flow among ‘on’, ‘off’ or ‘auto’. See Flow. 

C-a F

(fit)
Resize the window to the current region size. See Window Size. 

C-a C-g

(vbell)
Toggle visual bell mode. See Bell. 

C-a h

(hardcopy)
Write a hardcopy of the current window to the file “hardcopy.n”. See Hardcopy. 

C-a H

(log)
Toggle logging of the current window to the file “screenlog.n”. See Log. 

C-a iC-a C-i

(info)
Show info about the current window. See Info. 

C-a kC-a C-k

(kill)
Destroy the current window. See Kill. 

C-a lC-a C-l

(redisplay)
Fully refresh the current window. See Redisplay. 

C-a L

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

C-a mC-a C-m

(lastmsg)
Repeat the last message displayed in the message line. See Last Message. 

C-a M

(monitor) Toggle monitoring of the current window. See Monitor. 

C-a <SPC>C-a nC-a C-n

(next)
Switch to the next window. See Selecting. 

C-a N

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

C-a pC-a C-pC-a C-hC-a <BackSpace>

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

C-a qC-a C-q

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

C-a Q

(only)
Delete all regions but the current one. See Regions. 

C-a rC-a C-r

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

C-a sC-a C-s

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

C-a S

(split)
Split the current region into two new ones. See Regions. 

C-a tC-a C-t

(time)
Show the load average and xref. See Time. 

C-a v

(version)
Display the version and compilation date. See Version. 

C-a C-v

(digraph)
Enter digraph. See Digraph. 

C-a wC-a C-w

(windows)
Show a list of active windows. See Windows. 

C-a W

(width)
Toggle between 80 and 132 columns. See Window Size. 

C-a xC-a C-x

(lockscreen)
Lock your terminal. See Lock. 

C-a X

(remove)
Kill the current region. See Regions. 

C-a zC-a C-z

(suspend)
Suspend screen. See Suspend. 

C-a Z

(reset)
Reset the virtual terminal to its “power-on” values. See Reset. 

C-a .

(dumptermcap)
Write out a .termcap file. See Dump Termcap. 

C-a ?

(help)
Show key bindings. See Help. 

C-a C-\

(quit)
Kill all windows and terminate screen. See Quit. 

C-a :

(colon)
Enter a command line. See Colon. 

C-a [C-a C-[C-a <ESC>

(copy)
Enter copy/scrollback mode. See Copy. 

C-a ]C-a C-]

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

C-a {C-a }

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

C-a >

(writebuf)
Write the paste buffer out to the screen-exchange file. See Screen Exchange. 

C-a <

(readbuf)
Read the screen-exchange file into the paste buffer. See Screen Exchange. 

C-a =

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

C-a _

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

C-a ,

(license)
Show the copyright page. 

C-a *

(displays)
Show the listing of attached displays.

5.2 Command Summary

acladd usernames

Allow other users in this session. See Multiuser Session. 

aclchg usernames permbits list

Change a user's permissions. See Multiuser Session. 

acldel username

Disallow other user in this session. See Multiuser Session. 

aclgrp usrname [groupname]

Inherit permissions granted to a group leader. See Multiuser Session. 

aclumask [users]+/-bits ...

Predefine access to new windows. See Umask. 

activity message

Set the activity notification message. See Monitor. 

addacl usernames

Synonym to acladd. See Multiuser Session. 

allpartial state

Set all windows to partial refresh. See Redisplay. 

altscreen state

Enables support for the "alternate screen" terminal capability. See Redisplay. 

at [ident][#|*|%] command [args]

Execute a command at other displays or windows. See At. 

attrcolor attrib [attribute/color-modifier]

Map attributes to colors. See Attrcolor. 

autodetach state

Automatically detach the session on SIGHUP. See Detach. 

autonuke state

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

backtick id lifespan autorefresh command [args]

Define a command for the backtick string escape. See Backtick. 

bce [state]

Change background color erase. See Character Processing. 

bell_msg [message]

Set the bell notification message. See Bell. 

bind [-c class] key [command [args]]

Bind a command to a key. See Bind. 

bindkey [opts] [string [cmd args]]

Bind a string to a series of keystrokes. See Bindkey. 

blanker

Blank the screen. See Screen Saver. 

blankerprg

Define a blanker program. See Screen Saver. 

break [duration]

Send a break signal to the current window. See Break. 

breaktype [tcsendbreak | TCSBRK | TIOCSBRK]

Specify how to generate breaks. See Break. 

bufferfile [exchange-file]

Select a file for screen-exchange. See Screen Exchange. 

c1 [state]

Change c1 code processing. See Character Processing. 

caption mode [string]

Change caption mode and string. See Regions. 

chacl usernames permbits list

Synonym to aclchg. See Multiuser Session. 

charset set

Change character set slot designation. See Character Processing. 

chdir [directory]

Change the current directory for future windows. See Chdir. 

clear

Clear the window screen. See Clear. 

colon

Enter a screen command. See Colon. 

command [-c class]

Simulate the screen escape key. See Command Character. 

compacthist [state]

Selects compaction of trailing empty lines. See Scrollback. 

console [state]

Grab or ungrab console output. See Console. 

copy

Enter copy mode. See Copy. 

copy_reg [key]

Removed. Use paste instead. See Registers. 

crlf state

Select line break behavior for copying. See Line Termination. 

debug state

Suppress/allow debugging output. See Debug. 

defautonuke state

Select default autonuke behavior. See Autonuke. 

defbce state

Select background color erase. See Character Processing. 

defbreaktype [tcsendbreak | TCSBRK | TIOCSBRK]

Specify the default for generating breaks. See Break. 

defc1 state

Select default c1 processing behavior. See Character Processing. 

defcharset [set]

Change defaul character set slot designation. See Character Processing. 

defencoding enc

Select default window encoding. See Character Processing. 

defescape xy

Set the default command and meta characters. See Command Character. 

defflow fstate

Select default flow control behavior. See Flow. 

defgr state

Select default GR processing behavior. See Character Processing. 

defhstatus [status]

Select default window hardstatus line. See Hardstatus. 

deflog state

Select default window logging behavior. See Log. 

deflogin state

Select default utmp logging behavior. See Login. 

defmode mode

Select default file mode for ptys. See Mode. 

defmonitor state

Select default activity monitoring behavior. See Monitor. 

defnonblock state|numsecs

Select default nonblock mode. See Nonblock. 

defobuflimit limit

Select default output buffer limit. See Obuflimit. 

defscrollback num

Set default lines of scrollback. See Scrollback. 

defshell command

Set the default program for new windows. See Shell. 

defsilence state

Select default idle monitoring behavior. See Silence. 

defslowpaste msec

Select the default inter-character timeout when pasting. See Paste. 

defutf8 state

Select default character encoding. See Character Processing. 

defwrap state

Set default line-wrapping behavior. See Wrap. 

defwritelock on|off|auto

Set default writelock behavior. See Multiuser Session. 

defzombie [keys]

Keep dead windows. See Zombie. 

detach [-h]

Disconnect screen from the terminal. See Detach. 

digraph

Enter digraph sequence. See Digraph. 

dinfo

Display terminal information. See Info. 

displays

List currently active user interfaces. See Displays. 

dumptermcap

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

echo [-n] message

Display a message on startup. See Startup. 

encoding enc [denc]

Set the encoding of a window. See Character Processing. 

escape xy

Set the command and meta characters. See Command Character. 

eval command1 [command2 ...]

Parse and execute each argument. See Eval. 

exec [[fdpat] command [args ...]]

Run a subprocess (filter). See Exec. 

fit

Change window size to current display size. See Window Size. 

flow [fstate]

Set flow control behavior. See Flow. 

focus

Move focus to next region. See Regions. 

gr [state]

Change GR charset processing. See Character Processing. 

hardcopy [-h] [file]

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

hardcopy_append state

Append to hardcopy files. See Hardcopy. 

hardcopydir directory

Place, where to dump hardcopy files. See Hardcopy. 

hardstatus [state]

Use the hardware status line. See Hardware Status Line. 

height [lines [cols]]

Set display height. See Window Size. 

help [-c class]

Display current key bindings. See Help. 

history

Find previous command beginning .... See History. 

hstatus status

Change the window's hardstatus line. See Hardstatus. 

idle [timeout [cmd args]]

Define a screen saver command. See Screen Saver. 

ignorecase [state]

Ignore character case in searches. See Searching. 

info

Display window settings. See Info. 

ins_reg [key]

Removed, use paste instead. See Registers. 

kill

Destroy the current window. See Kill. 

lastmsg

Redisplay the last message. See Last Message. 

license

Display licensing information. See Startup. 

lockscreen

Lock the controlling terminal. See Lock. 

log [state]

Log all output in the current window. See Log. 

logfile filename

Place where to collect logfiles. See Log. 

login [state]

Log the window in /etc/utmp. See Login. 

logtstamp [state]

Configure logfile time-stamps. See Log. 

mapdefault

Use only the default mapping table for the next keystroke. See Bindkey Control. 

mapnotnext

Don't try to do keymapping on the next keystroke. See Bindkey Control. 

maptimeout timo

Set the inter-character timeout used for keymapping. See Bindkey Control. 

markkeys string

Rebind keys in copy mode. See Copy Mode Keys. 

maxwin n

Set the maximum window number. See Maxwin. 

meta

Insert the command character. See Command Character. 

monitor [state]

Monitor activity in window. See Monitor. 

msgminwait sec

Set minimum message wait. See Message Wait. 

msgwait sec

Set default message wait. See Message Wait. 

multiuser state

Go into single or multi user mode. See Multiuser Session. 

nethack state

Use nethack-like error messages. See Nethack. 

next

Switch to the next window. See Selecting. 

nonblock [state|numsecs]

Disable flow control to the current display. See Nonblock.|numsecs] 

number [n]

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

obuflimit [limit]

Select output buffer limit. See Obuflimit. 

only

Kill all other regions. See Regions. 

other

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

partial state

Set window to partial refresh. See Redisplay. 

password [crypted_pw]

Set reattach password. See Detach. 

paste [src_regs [dest_reg]]

Paste contents of paste buffer or registers somewhere. See Paste. 

pastefont [state]

Include font information in the paste buffer. See Paste. 

pow_break

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

pow_detach

Detach and hang up. See Power Detach. 

pow_detach_msg [message]

Set message displayed on pow_detach. See Power Detach. 

prev

Switch to the previous window. See Selecting. 

printcmd [cmd]

Set a command for VT100 printer port emulation. See Printcmd. 

process [key]

Treat a register as input to screen. See Registers. 

quit

Kill all windows and exit. See Quit. 

readbuf [-e encoding] [filename]

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

readreg [-e encoding] [reg [file]]

Load a register from paste buffer or file. See Registers. 

redisplay

Redisplay the current window. See Redisplay. 

register [-e encoding] key string

Store a string to a register. See Registers. 

remove

Kill current region. See Regions. 

removebuf

Delete the screen-exchange file. See Screen Exchange. 

reset

Reset the terminal settings for the window. See Reset. 

resize [(+/-)lines]

Grow or shrink a region 

screen [opts] [n] [cmd [args]]

Create a new window. See Screen Command. 

scrollback num

Set size of scrollback buffer. See Scrollback. 

select [n]

Switch to a specified window. See Selecting. 

sessionname [name]

Name this session. See Session Name. 

setenv [var [string]]

Set an environment variable for new windows. See Setenv. 

setsid state

Controll process group creation for windows. See Setsid. 

shell command

Set the default program for new windows. See Shell. 

shelltitle title

Set the default name for new windows. See Shell. 

silence [state|seconds]

Monitor a window for inactivity. See Silence. 

silencewait seconds

Default timeout to trigger an inactivity notify. See Silence. 

sleep num

Pause during startup. See Startup. 

slowpaste msec

Slow down pasting in windows. See Paste. 

source file

Run commands from a file. See Source. 

sorendition [attr [color]]

Change text highlighting. See Sorendition. 

split

Split region into two parts. See Regions. 

startup_message state

Display copyright notice on startup. See Startup. 

stuff string

Stuff a string in the input buffer of a window. See Paste. 

su [username [password [password2]]]

Identify a user. See Multiuser Session. 

suspend

Put session in background. See Suspend. 

term term

Set $TERM for new windows. See Term. 

termcap term terminal-tweaks [window-tweaks]

Tweak termcap entries for best performance. See Termcap Syntax. 

terminfo term terminal-tweaks [window-tweaks]

Ditto, for terminfo systems. See Termcap Syntax. 

termcapinfo term terminal-tweaks [window-tweaks]

Ditto, for both systems. See Termcap Syntax. 

time [string]

Display time and load average. See Time. 

title [windowtitle]

Set the name of the current window. See Title Command. 

umask [users]+/-bits ...

Synonym to aclumask. See Umask. 

unsetenv var

Unset environment variable for new windows. See Setenv. 

utf8 [state [dstate]]

Select character encoding of the current window. See Character Processing. 

vbell [state]

Use visual bell. See Bell. 

vbell_msg [message]

Set vbell message. See Bell. 

vbellwait sec

Set delay for vbell message. See Bell. 

version

Display screen version. See Version. 

wall message

Write a message to all displays. See Multiuser Session. 

width [cols [lines]]

Set the width of the window. See Window Size. 

windowlist [-b] | string [string] | title [title]

Present a list of all windows for selection. See Windowlist. 

windows

List active windows. See Windows. 

wrap [state]

Control line-wrap behavior. See Wrap. 

writebuf [-e encoding] [filename]

Write paste buffer to screen-exchange file. See Screen Exchange. 

writelock on|off|auto

Grant exclusive write permission. See Multiuser Session. 

xoff

Send an XOFF character. See XON/XOFF. 

xon

Send an XON character. See XON/XOFF. 

zmodem [off|auto|catch|pass]

Define how screen treats zmodem requests. See Zmodem. 

zombie [keys [onerror] ]

Keep dead windows. See Zombie.

6 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. The number of windows is limited at compile-time by the MAXWIN configuration parameter.

• Chdir: Change the working directory for new windows.
• Screen Command: Create a new window.
• Setenv: Set environment variables for new windows.
• Shell: Parameters for shell windows.
• Term: Set the terminal type for new windows.
• Window Types: Creating different types of windows.

6.1 Chdir

6.2 Screen Command

Thus, if your .screenrc contains the lines

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

screen creates a shell window (in window #1) and a window with a TELNET connection to the machine foobar (with no flow-control using the title ‘foobar’ in window #2) and will write a logfile ‘screenlog.2’ of the telnet session. 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.

6.3 Setenv

6.4 Shell

6.5 Term

6.6 Window Types

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

• The normal window contains a shell (default, if no parameter is given) or any other system command that could be executed from a shell. (e.g. ‘slogin’, etc...).
• If a tty (character special device) name (e.g. ‘/dev/ttya’) is specified as the first parameter, then the window is directly connected to this device. This window type is similar to ‘screen cu -l /dev/ttya’. Read and write access is required on the device node, an exclusive open is attempted on the node to mark the connection line as busy. An optional parameter is allowed consisting of a comma separated list of flags in the notation used by ‘stty(1)’:

  <baud_rate>

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

  cs8 or cs7

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

  ixon or -ixon

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

  ixoff or -ixoff

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

  istrip or -istrip

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

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

  For tty windows, the info command shows some of the modem control lines in the status line. These may include ‘RTS’, ‘CTS’, ‘DTR’, ‘CD’ and more. This depends rather on on the available ioctl()'s and system header files than on the physical capabilities of the serial board. The name of a logical low (inactive) signal is preceded by an exclamation mark (‘!’), otherwise the signal is logical high (active). Unsupported but shown signals are usually shown low. When the CLOCAL status bit is true, the whole set of modem signals is placed inside curly braces (‘{’ and ‘}’). When the CRTSCTS or TIOCSOFTCAR bit is true, the signals ‘CTS’ or ‘CD’ are shown in parenthesis, respectively.

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

• If the first parameter is //telnet, the second parameter is expected to be a host name, and an optional third parameter may specify a TCP port number (default decimal 23). Screen will connect to a server listening on the remote host and use the telnet protocol to communicate with that server.

  For telnet windows, the command info shows details about the connection in square brackets (‘[’ and ‘]’) at the end of the status line.

  b

  BINARY. The connection is in binary mode. 

  e

  ECHO. Local echo is disabled. 

  c

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

  t

  TTYPE. The terminal type has been requested by the remote host. Screen sends the name screen unless instructed otherwise (see also the command ‘term’). 

  w

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

  f

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

  Additional flags for debugging are ‘x’, ‘t’ and ‘n’ (XDISPLOC, TSPEED and NEWENV).

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

7 Selecting a Window

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

• Next and Previous: Forward or back one window.
• Other Window: Switch back and forth between two windows.
• Select: Switch to a window (and to one after kill).
• Windowlist: Present a list of all windows for selection.

7.1 Moving Back and Forth

7.2 Other Window

7.3 Select

7.4 Windowlist

8 Session Management Commands

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

• Detach: Disconnect screen from your terminal.
• Power Detach: Detach and log out.
• Lock: Lock your terminal temporarily.
• Multiuser Session: Changing number of allowed users.
• Session Name: Rename your session for later reattachment.
• Suspend: Suspend your session.
• Quit: Terminate your session.

8.1 Detach

8.2 Power Detach

8.3 Lock

8.4 Multiuser Session

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

• Multiuser: Enable / Disable multiuser mode.
• Acladd: Enable a specific user.
• Aclchg: Change a users permissions.
• Acldel: Disable a specific user.
• Aclgrp: Grant a user permissions to other users.
• Displays: List all active users at their displays.
• Umask: Predefine access to new windows.
• Wall: Write a message to all users.
• Writelock: Grant exclusive window access.
• Su: Substitute user.

8.4.1 Multiuser

8.4.2 Acladd

8.4.3 Aclchg

8.4.4 Acldel

8.4.5 Aclgrp

8.4.6 Displays

8.4.7 aclumask

8.4.8 Wall

8.4.9 Writelock

8.4.10 Su

8.5 Session Name

8.6 Suspend

8.7 Quit

9 Regions

Screen has the ability to display more than one window on the user's display. This is done by splitting the screen in regions, which can contain different windows.

• Split: Split a region into two
• Focus: Change to the next region
• Only: Delete all other regions
• Remove: Delete the current region
• Resize: Grow or shrink a region
• Caption: Control the window's caption
• Fit: Resize a window to fit the region

9.1 Split

9.2 Focus

9.3 Only

9.4 Remove

9.5 Resize

9.6 Caption

9.7 Fit

10 Window Settings

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

• Naming Windows: Control the name of the window
• Console: See the host's console messages
• Kill: Destroy an unwanted window
• Login: Control /etc/utmp logging
• Mode: Control the file mode of the pty
• Monitor: Watch for activity in a window
• Windows: List the active windows
• Hardstatus: Set a window's hardstatus line

10.1 Naming Windows (Titles)

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

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

• Title Command: The title command.
• Dynamic Titles: Make shell windows change titles dynamically.
• Title Prompts: Set up your shell prompt for dynamic Titles.
• Title Screenrc: Set up Titles in your .screenrc.

10.1.1 Title Command

10.1.2 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 searchportion 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.

10.1.3 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='{No value for `esc'}[0000m{No value for `esc'}k{No value for `esc'}\% '

The escape-sequence ‘{No value for `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='printf "\033k\033\134"'

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

10.1.4 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).

10.2 Console

10.3 Kill

10.4 Login

10.5 Mode

10.6 Monitoring

10.7 Windows

10.8 Hardstatus

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. 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.

11 Virtual Terminal

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

• Control Sequences: Details of the internal VT100 emulation.
• Input Translation: How keystrokes are remapped.
• Digraph: Entering digraph sequences.
• Bell: Getting your attention.
• Clear: Clear the window display.
• Info: Terminal emulation statistics.
• Redisplay: When the display gets confusing.
• Wrap: Automatic margins.
• Reset: Recovering from ill-behaved applications.
• Window Size: Changing the size of your terminal.
• Character Processing: Change the effect of special characters.

11.1 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 ] 0 ; string ^G (A) Operating System Command (Hardstatus, xterm
title hack)
ESC ] 83 ; cmd ^G (A) Execute screen command. This only works if
multi-user support is compiled into screen.
The pseudo-user ":window:" is used to check
the access control list. Use "addacl :window:
-rwx #?" to create a user with no rights and
allow only the needed commands.
Control-N (A) Lock Shift G1 (SO)
Control-O (A) Lock Shift G0 (SI)
ESC n (A) Lock Shift G2
ESC o (A) Lock Shift G3
ESC N (A) Single Shift G2
ESC O (A) Single Shift G3
ESC ( Pcs (A) Designate character set as G0
ESC ) Pcs (A) Designate character set as G1
ESC * Pcs (A) Designate character set as G2
ESC + Pcs (A) Designate character set as G3
ESC [ Pn ; Pn H Direct Cursor Addressing
ESC [ Pn ; Pn f same as above
ESC [ Pn J Erase in Display
Pn = None or 0 From Cursor to End of Screen
1 From Beginning of Screen to Cursor
2 Entire Screen
ESC [ Pn K Erase in Line
Pn = None or 0 From Cursor to End of Line
1 From Beginning of Line to Cursor
2 Entire Line
ESC [ Pn X Erase character
ESC [ Pn A Cursor Up
ESC [ Pn B Cursor Down
ESC [ Pn C Cursor Right
ESC [ Pn D Cursor Left
ESC [ Pn E Cursor next line
ESC [ Pn F Cursor previous line
ESC [ Pn G Cursor horizontal position
ESC [ Pn ` same as above
ESC [ Pn d Cursor vertical position
ESC [ Ps ;...; Ps m Select Graphic Rendition
Ps = None or 0 Default Rendition
1 Bold
2 (A) Faint
3 (A) Standout Mode (ANSI: Italicized)
4 Underlined
5 Blinking
7 Negative Image
22 (A) Normal Intensity
23 (A) Standout Mode off (ANSI: Italicized off)
24 (A) Not Underlined
25 (A) Not Blinking
27 (A) Positive Image
30 (A) Foreground Black
31 (A) Foreground Red
32 (A) Foreground Green
33 (A) Foreground Yellow
34 (A) Foreground Blue
35 (A) Foreground Magenta
36 (A) Foreground Cyan
37 (A) Foreground White
39 (A) Foreground Default
40 (A) Background Black
... ...
49 (A) Background Default
ESC [ Pn g Tab Clear
Pn = None or 0 Clear Tab at Current Position
3 Clear All Tabs
ESC [ Pn ; Pn r (V) Set Scrolling Region
ESC [ Pn I (A) Horizontal Tab
ESC [ Pn Z (A) Backward Tab
ESC [ Pn L (A) Insert Line
ESC [ Pn M (A) Delete Line
ESC [ Pn @ (A) Insert Character
ESC [ Pn P (A) Delete Character
ESC [ Pn S Scroll Scrolling Region Up
ESC [ Pn T Scroll Scrolling Region Down
ESC [ Pn ^ same as above
ESC [ Ps ;...; Ps h Set Mode
ESC [ Ps ;...; Ps l Reset Mode
Ps = 4 (A) Insert Mode
20 (A) ‘Automatic Linefeed’ Mode.
34 Normal Cursor Visibility
?1 (V) Application Cursor Keys
?3 (V) Change Terminal Width to 132 columns
?5 (V) Reverse Video
?6 (V) ‘Origin’ Mode
?7 (V) ‘Wrap’ Mode
?9 X10 mouse tracking
?25 (V) Visible Cursor
?47 Alternate Screen (old xterm code)
?1000 (V) VT200 mouse tracking
?1047 Alternate Screen (new xterm code)
?1049 Alternate Screen (new xterm code)
ESC [ 5 i (A) Start relay to printer (ANSI Media Copy)
ESC [ 4 i (A) Stop relay to printer (ANSI Media Copy)
ESC [ 8 ; Ph ; Pw t Resize the window to ‘Ph’ lines and
‘Pw’ columns (SunView special)
ESC [ c Send VT100 Identification String
ESC [ x (V) Send Terminal Parameter Report
ESC [ > c Send Secondary Device Attributes String
ESC [ 6 n Send Cursor Position Report

11.2 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 commandstuff, see 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 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[23~
Function key 12 F2 stuff \033[24~
Home kh stuff \033[1~
End kH stuff \033[4~
Insert kI stuff \033[2~
Delete kD stuff \033[3~
Page up kP stuff \033[5~
Page down kN stuff \033[6~
Keypad 0 f0 stuff 0
stuff \033Op (A)
Keypad 1 f1 stuff 1
stuff \033Oq (A)
Keypad 2 f2 stuff 2
stuff \033Or (A)
Keypad 3 f3 stuff 3
stuff \033Os (A)
Keypad 4 f4 stuff 4
stuff \033Ot (A)
Keypad 5 f5 stuff 5
stuff \033Ou (A)
Keypad 6 f6 stuff 6
stuff \033Ov (A)
Keypad 7 f7 stuff 7
stuff \033Ow (A)
Keypad 8 f8 stuff 8
stuff \033Ox (A)
Keypad 9 f9 stuff 9
stuff \033Oy (A)
Keypad + f+ stuff +
stuff \033Ok (A)
Keypad - f- stuff -
stuff \033Om (A)
Keypad * f* stuff *
stuff \033Oj (A)
Keypad / f/ stuff /
stuff \033Oo (A)
Keypad = fq stuff =
stuff \033OX (A)
Keypad . f. stuff .
stuff \033On (A)
Keypad , f, stuff ,
stuff \033Ol (A)
Keypad enter fe stuff \015
stuff \033OM (A)

11.3 Digraph

11.4 Bell

11.5 Clear

11.6 Info

11.7 Redisplay

11.8 Wrap

11.9 Reset

11.10 Window Size

11.11 Character Processing

12 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.

• Copy: Copy from scrollback to buffer
• Paste: Paste from buffer into window
• Registers: Longer-term storage
• Screen Exchange: Sharing data between screen users
• History: Recalling previous input

12.1 Copying

• Line Termination: End copied lines with CR/LF
• Scrollback: Set the size of the scrollback buffer
• Copy Mode Keys: Remap keys in copy mode
• Movement: Move around in the scrollback buffer
• Marking: Select the text you want
• Repeat count: Repeat a command
• Searching: Find the text you want
• Specials: Other random keys

12.1.1 CR/LF

12.1.2 Scrollback

12.1.3 markkeys

12.1.4 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.

B, E move the cursor WORD by WORD (as in vi).

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

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.

12.1.5 Marking

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

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

W marks exactly one word.

12.1.6 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.

12.1.7 Searching

/ vi-like search forward.

? vi-like search backward.

C-a s emacs style incremental search forward.

C-r emacs style reverse i-search.

12.1.8 Specials

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

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

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

and notice the difference in the amount of text copied.

J joins lines. It toggles between 4 modes: lines separated by a newline character (012), lines glued seamless, lines separated by a single space or comma separated lines. 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 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.

12.2 Paste

12.3 Registers

12.4 Screen Exchange

12.5 History

13 Subprocess Execution

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

• Exec: The exec command syntax.
• Using Exec: Weird things that filters can do.

13.1 Exec

13.2 Using Exec

Abbreviations:

• Whitespace between the word ‘exec’ and fdpat and the command name can be omitted.
• Trailing dots and a fdpat consisting only of dots can be omitted.
• A simple ‘|’ is synonymous for the ‘!..|’ pattern.
• The word ‘exec’ can be omitted when the ‘|’ abbreviation is used.
• The word ‘exec’ can always be replaced by leading ‘!’.

Examples:

!/bin/shexec /bin/shexec ... /bin/sh

All of the above are equivalent. 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 19200exec!stty 19200exec !.. stty 19200

All of the above are equivalent. 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. 

|lessexec !..| less

Both are equivalent. 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.

14 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.

• Bind: bind syntax.
• Bind Examples: Using bind.
• Command Character: The character used to start keyboard commands.
• Help: Show current key bindings.
• Bindkey: bindkey syntax.
• Bindkey Examples: Some easy examples.
• Bindkey Control: How to control the bindkey mechanism.

14.1 The bind command

14.2 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 superuser shell and a scrollback buffer of 1000 lines.

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

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

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

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

14.3 Command Character

14.4 Help

14.5 Bindkey

14.6 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 abbreviation of the word ‘barfoo’. Timeout is disabled so that users can type slowly.

bindkey "\024" mapdefault

This key-binding makes ‘C-t’ an escape character for key-bindings. 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’).

14.7 Bindkey Control

15 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).

• Flow Control Summary: The effect of screen flow control
• Flow: Setting the flow control behavior
• XON/XOFF: Sending XON or XOFF to the window

15.1 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.

15.2 Flow

15.3 XON and XOFF

16 Termcap

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

• Window Termcap: Choosing a termcap entry for the window.
• Dump Termcap: Write out a termcap entry for the window.
• Termcap Syntax: The termcap and terminfo commands.
• Termcap Examples: Uses for termcap.
• Special Capabilities: Non-standard capabilities used by screen.
• Autonuke: Flush unseen output
• Obuflimit: Allow pending output when reading more
• Character Translation: Emulating fonts and charsets.

16.1 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 $TERMCAPvariable reflecting the capabilities of the virtual terminal emulated. Furthermore, the variable $WINDOW is set to the window number of each window.

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

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

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

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

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

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

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

16.2 Write out the window's termcap entry

16.3 The termcap command

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

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

16.4 Termcap Examples

Some examples:

termcap xterm* xn:hs@

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

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

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

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

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

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

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

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

16.5 Special Terminal Capabilities

The following table describes all terminal capabilities that are recognized by screen and are not in the termcap manual (see Termcap). You can place these capabilities in your termcap entries (in /etc/termcap) or use them with the commands termcap, terminfo and termcapinfo in your screenrc files. It is often not possible to place these capabilities in the terminfo database.

‘LP’

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

‘Z0’

(str)
Change width to 132 columns. 

‘Z1’

(str)
Change width to 80 columns. 

‘WS’

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

‘NF’

(bool)
Terminal doesn't need flow control. Send ^S and ^Q direct to the application. Same as flow off. The opposite of this capability is ‘nx’. 

‘G0’

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

‘S0’

(str)
Switch charset ‘G0’ to the specified charset. Default is ‘\E(%.’. 

‘E0’

(str)
Switch charset ‘G0’ back to standard charset. Default is ‘\E(B’. 

‘C0’

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

‘CS’

(str)
Switch cursor-keys to application mode. 

‘CE’

(str)
Switch cursor-keys to cursor mode. 

‘AN’

(bool)
Enable autonuke for displays of this terminal type. (see Autonuke). 

‘OL’

(num)
Set the output buffer limit. See the ‘obuflimit’ command (see Obuflimit) for more details. 

‘KJ’

(str)
Set the encoding of the terminal. See the ‘encoding’ command (see Character Processing) for valid encodings. 

‘AF’

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

‘AB’

(str)
Same as ‘AF’, but change background color. 

‘AX’

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

‘XC’

(str)
Describe a translation of characters to strings depending on the current font. (see Character Translation). 

‘XT’

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

‘C8’

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

‘TF’

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

16.6 Autonuke

16.7 Obuflimit

16.8 Character Translation

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

Syntax:

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

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

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

Here is an example:

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

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

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

This example shows one use of the extension:

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

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

17 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.

• Privacy Message: Using the message line from your program.
• Hardware Status Line: Use the terminal's hardware status line.
• Last Message: Redisplay the last message.
• Message Wait: Control how long messages are displayed.

17.1 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 "{No value for `esc'}^Hello world from window $WINDOW{No value for `esc'}\"

where ‘{No value for `esc'}’ is ASCII ESC and the ‘^’ that follows it is a literal caret or up-arrow.

17.2 Hardware Status Line

17.3 Display Last Message

17.4 Message Wait

18 Logging

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

• Hardcopy: Dump the current screen to a file
• Log: Log the output of a window to a file

18.1 hardcopy

18.2 log

19 Startup

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

• echo: Display a message.
• sleep: Pause execution of the .screenrc.
• Startup Message: Control display of the copyright notice.

19.1 echo

19.2 sleep

19.3 Startup Message

20 Miscellaneous commands

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

• At: Execute a command at other displays or windows.
• Break: Send a break signal to the window.
• Debug: Suppress/allow debugging output.
• License: Display the disclaimer page.
• Nethack: Use nethack-like error messages.
• Nonblock: Disable flow-control to a display.
• Number: Change the current window's number.
• Silence: Notify on inactivity.
• Time: Display the time and load average.
• Verbose: Display window creation commands.
• Version: Display the version of screen.
• Zombie: Keep dead windows.
• Printcmd: Set command for VT100 printer port emulation.
• Sorendition: Change the text highlighting method.
• Attrcolor: Map attributes to colors.
• Setsid: Change process group management.
• Eval: Parse and execute arguments.
• Maxwin: Set the maximum window number.
• Backtick: Program a command for a backtick string escape.
• Screen Saver: Define a screen safer.
• Zmodem: Define how screen treats zmodem requests.

20.1 At

20.2 Break

20.3 Debug

20.4 License

20.5 Nethack

20.6 Nonblock

20.7 Number

20.8 Silence

20.9 Time

20.10 Verbose

20.11 Version

20.12 Zombie

20.13 Printcmd

20.14 Sorendition

20.15 Attrcolor

20.16 Setsid

20.17 Eval

20.18 Maxwin

20.19 Backtick

20.20 Screen Saver

20.21 Zmodem

21 String Escapes

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

Here is the full list of supported escapes:

%

the escape character itself 

a

either am or pm 

A

either AM or PM 

c

current time HH:MM in 24h format 

C

current time HH:MM in 12h format 

d

day number 

D

weekday name 

f

flags of the window 

F

sets %? to true if the window has the focus 

h

hardstatus of the window 

H

hostname of the system 

l

current load of the system 

m

month number 

M

month name 

n

window number 

s

seconds 

S

session name 

t

window title 

u

all other users on this window 

w

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

W

all window numbers and names except the current one 

y

last two digits of the year number 

Y

full year number 

?

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

:

else part of %? 

=

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

<

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

>

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

{

attribute/color modifier string terminated by the next } 

`

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

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

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

+

add the specified set to the current attributes 

-

remove the set from the current attributes 

!

invert the set in the current attributes 

=

change the current attributes to the specified set

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

d

dim 

u

underline 

b

bold 

r

reverse 

s

standout 

B

blinking

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

k

black 

r

red 

g

green 

y

yellow 

b

blue 

m

magenta 

c

cyan 

w

white 

d

default color 

.

leave color unchanged

The capitalized versions of the letter specify bright colors. You can also use the pseudo-color ‘i’ to set just the brightness and leave the color unchanged.

A one digit/letter color description is treated as foreground or background color dependent on the current attributes: if reverse mode is set, the background color is changed instead of the foreground color. If you don't like this, prefix the color with a ‘.’. If you want the same behavior for two-letter color descriptions, also prefix them with a ‘.’.

As a special case, ‘%{-}’ restores the attributes and colors that were set before the last change was made (i.e. pops one level of the color-change stack).

Examples:

‘G’

set color to bright green 

‘+b r’

use bold red 

‘= yd’

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

‘%-Lw%{= BW}%50>%n%f* %t%{-}%+Lw%<’

The available windows centered at the current win dow and truncated to the available width. The current window is displayed white on blue. This can be used with ‘hardstatus alwayslastline’. 

‘%?%F%{.R.}%?%3n %t%? [%h]%?’

The window number and title and the window's hardstatus, if one is set. Also use a red background if this is the active focus. Useful for ‘caption string’.

22 Environment Variables

COLUMNS

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

HOME

Directory in which to look for .screenrc. 

LINES

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

LOCKPRG

Screen lock program. 

NETHACKOPTIONS

Turns on nethack option. 

PATH

Used for locating programs to run. 

SCREENCAP

For customizing a terminal's TERMCAP value. 

SCREENDIR

Alternate socket directory. 

SCREENRC

Alternate user screenrc file. 

SHELL

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

STY

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

SYSSCREENRC

Alternate system screenrc file. 

TERM

Terminal name. 

TERMCAP

Terminal description. 

WINDOW

Window number of a window (at creation time).

23 Files Referenced

.../screen-4.?.??/etc/screenrc.../screen-4.?.??/etc/etcscreenrc

Examples in the screen distribution package for private and global initialization files. 

$SYSSCREENRC/local/etc/screenrc

screen initialization commands 

$SCREENRC$HOME/.iscreenrc$HOME/.screenrc

Read in after /local/etc/screenrc 

$SCREENDIR/S-login /local/screens/S-login

Socket directories (default) 

/usr/tmp/screens/S-login

Alternate socket directories. 

socket directory/.termcap

Written by the dumptermcap command 

/usr/tmp/screens/screen-exchange or/tmp/screen-exchange

screen interprocess communication buffer 

hardcopy.[0-9]

Screen images created by the hardcopy command 

screenlog.[0-9]

Output log files created by the log command 

/usr/lib/terminfo/?/* or/etc/termcap

Terminal capability databases 

/etc/utmp

Login records 

$LOCKPRG

Program for locking the terminal.

24 Credits

Authors 
=======

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

Contributors 
============

Ken Beal (kbeal@amber.ssd.csd.harris.com),
Rudolf Koenig (rfkoenig@informatik.uni-erlangen.de),
Toerless Eckert (eckert@informatik.uni-erlangen.de),
Wayne Davison (davison@borland.com),
Patrick Wolfe (pat@kai.com, kailand!pat),
Bart Schaefer (schaefer@cse.ogi.edu),
Nathan Glasser (nathan@brokaw.lcs.mit.edu),
Larry W. Virden (lvirden@cas.org),
Howard Chu (hyc@hanauma.jpl.nasa.gov),
Tim MacKenzie (tym@dibbler.cs.monash.edu.au),
Markku Jarvinen (mta@{cc,cs,ee}.tut.fi),
Marc Boucher (marc@CAM.ORG),
Doug Siebert (dsiebert@isca.uiowa.edu),
Ken Stillson (stillson@tsfsrv.mitre.org),
Ian Frechett (frechett@spot.Colorado.EDU),
Brian Koehmstedt (bpk@gnu.ai.mit.edu),
Don Smith (djs6015@ultb.isc.rit.edu),
Frank van der Linden (vdlinden@fwi.uva.nl),
Martin Schweikert (schweik@cpp.ob.open.de),
David Vrona (dave@sashimi.lcu.com),
E. Tye McQueen (tye%spillman.UUCP@uunet.uu.net),
Matthew Green (mrg@eterna.com.au),
Christopher Williams (cgw@pobox.com),
Matt Mosley (mattm@access.digex.net),
Gregory Neil Shapiro (gshapiro@wpi.WPI.EDU),
Jason Merrill (jason@jarthur.Claremont.EDU),
Johannes Zellner (johannes@zellner.org),
Pablo Averbuj (pablo@averbuj.com).

Version 
=======

This manual describes version 4.1.0 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 Availability.

25 Bugs

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

• Known Bugs: Problems we know about.
• Reporting Bugs: How to contact the maintainers.
• Availability: Where to find the latest screen version.

25.1 Known Bugs

• ‘dm’ (delete mode) and ‘xs’ are not handled correctly (they are ignored). ‘xn’ is treated as a magic-margin indicator.
• screen has no clue about double-high or double-wide characters. But this is the only area where vttest is allowed to fail.
• It is not possible to change the environment variable $TERMCAP when reattaching under a different terminal type.
• The support of terminfo based systems is very limited. Adding extra capabilities to $TERMCAP may not have any effects.
• screen does not make use of hardware tabs.
• screen must be installed setuid root on most systems in order to be able to correctly change the owner of the tty device file for each window. Special permission may also be required to write the file /etc/utmp.
• Entries in /etc/utmp are not removed when screen is killed with SIGKILL. This will cause some programs (like "w" or "rwho") to advertise that a user is logged on who really isn't.
• screen may give a strange warning when your tty has no utmp entry.
• When the modem line was hung up, screen may not automatically detach (or quit) unless the device driver sends a HANGUP signal. To detach such a screen session use the -D or -d command line option.
• If a password is set, the command line options -d and -D still detach a session without asking.
• Both breaktype and defbreaktype change the break generating method used by all terminal devices. The first should change a window specific setting, where the latter should change only the default for new windows.
• When attaching to a multiuser session, the user's .screenrc file is not sourced. Each users personal settings have to be included in the .screenrc file from which the session is booted, or have to be changed manually.
• A weird imagination is most useful to gain full advantage of all the features.

25.2 Reporting Bugs

If you find a bug in Screen, please send electronic mail to ‘screen@uni-erlangen.de’, and also to ‘bug-gnu-utils@prep.ai.mit.edu’. Include the version number of Screen which you are using. Also include in your message the hardware and operating system, the compiler used to compile, a description of the bug behavior, and the conditions that triggered the bug. Please recompile screen with the ‘-DDEBUG’ 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.

25.3 Availability

Screen is available under the GNU copyleft.

The latest official release of screen available via anonymous ftp from ‘prep.ai.mit.edu’, ‘nic.funet.fi’ or any other GNU distribution site. The home site of screen is ‘ftp.uni-erlangen.de (131.188.3.71)’, in the directory pub/utilities/screen. The subdirectory ‘private’ contains the latest beta testing release. If you want to help, send a note to screen@uni-erlangen.de.

26 Installation

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: Where screen stores its handle.
• Compiling Screen

26.1 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 700 directory in the environment variable $SCREENDIR.

26.2 Compiling Screen

To compile and install screen:

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

This will create a config.h and Makefile for your machine. If configure fails for some reason, then look at the examples and comments found in the Makefile.in and config.h.in templates. Rename config.status toconfig.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: Startup Files
• availability: Availability
• binding: Key Binding
• bug report: Reporting Bugs
• bugs: Bugs
• capabilities: Special Capabilities
• command character: Command Character
• command line options: Invoking Screen
• command summary: Command Summary
• compiling screen: Compiling Screen
• control sequences: Control Sequences
• copy and paste: Copy and Paste
• customization: Customization
• environment: Environment
• escape character: Command Character
• files: Files
• flow control: Flow Control
• input translation: Input Translation
• installation: Installation
• introduction: Getting Started
• invoking: Invoking Screen
• key binding: Key Binding
• marking: Copy
• message line: Message Line
• multiuser session: Multiuser Session
• options: Invoking Screen
• overview: Overview
• regions: Regions
• screenrc: Startup Files
• scrollback: Copy
• socket directory: Socket Directory
• string escapes: String Escapes
• terminal capabilities: Special Capabilities
• title: Naming Windows
• window types: Window Types

Command Index

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

• acladd: Acladd
• aclchg: Aclchg
• acldel: Acldel
• aclgrp: Aclgrp
• aclumask: Umask
• activity: Monitor
• addacl: Acladd
• allpartial: Redisplay
• altscreen: Redisplay
• at: At
• attrcolor: Attrcolor
• autodetach: Detach
• autonuke: Autonuke
• backtick: Backtick
• bce: Character Processing
• bell_msg: Bell
• bind: Bind
• bindkey: Bindkey
• blanker: Screen Saver
• blankerprg: Screen Saver
• break: Break
• breaktype: Break
• bufferfile: Screen Exchange
• c1: Character Processing
• caption: Caption
• chacl: Aclchg
• charset: Character Processing
• chdir: Chdir
• clear: Clear
• colon: Colon
• command: Command Character
• compacthist: Scrollback
• console: Console
• copy: Copy
• copy_reg: Registers
• crlf: Line Termination
• debug: Debug
• defautonuke: Autonuke
• defbce: Character Processing
• defbreaktype: Break
• defc1: Character Processing
• defcharset: Character Processing
• defencoding: Character Processing
• defescape: Command Character
• defflow: Flow
• defgr: Character Processing
• defhstatus: Hardstatus
• deflog: Log
• deflogin: Login
• defmode: Mode
• defmonitor: Monitor
• defnonblock: Nonblock
• defobuflimit: Obuflimit
• defscrollback: Scrollback
• defshell: Shell
• defsilence: Silence
• defslowpaste: Paste
• defutf8: Character Processing
• defwrap: Wrap
• defwritelock: Writelock
• defzombie: Zombie
• detach: Detach
• digraph: Digraph
• dinfo: Info
• displays: Displays
• dumptermcap: Dump Termcap
• echo: echo
• encoding: Character Processing
• escape: Command Character
• eval: Eval
• exec: Exec
• fit: Fit
• flow: Flow
• focus: Focus
• gr: Character Processing
• hardcopy: Hardcopy
• hardcopy_append: Hardcopy
• hardcopydir: Hardcopy
• hardstatus: Hardware Status Line
• height: Window Size
• help: Help
• history: History
• hstatus: Hardstatus
• idle: Screen Saver
• ignorecase: Searching
• info: Info
• ins_reg: Registers
• kill: Kill
• lastmsg: Last Message
• license: License
• lockscreen: Lock
• log: Log
• logfile: Log
• login: Login
• logtstamp: Log
• mapdefault: Bindkey Control
• mapnotnext: Bindkey Control
• maptimeout: Bindkey Control
• markkeys: Copy Mode Keys
• maxwin: Maxwin
• meta: Command Character
• monitor: Monitor
• msgminwait: Message Wait
• msgwait: Message Wait
• multiuser: Multiuser
• nethack: Nethack
• next: Next and Previous
• nonblock: Nonblock
• number: Number
• obuflimit: Obuflimit
• only: Only
• other: Other Window
• partial: Redisplay
• password: Detach
• paste: Paste
• pastefont: Paste
• pow_break: Break
• pow_detach: Power Detach
• pow_detach_msg: Power Detach
• prev: Next and Previous
• printcmd: Printcmd
• process: Registers
• quit: Quit
• readbuf: Screen Exchange
• readreg: Paste
• redisplay: Redisplay
• register: Registers
• remove: Remove
• removebuf: Screen Exchange
• reset: Reset
• resize: Resize
• screen: Screen Command
• scrollback: Scrollback
• select: Select
• sessionname: Session Name
• setenv: Setenv
• setsid: Setsid
• shell: Shell
• shelltitle: Shell
• silence: Silence
• silencewait: Silence
• sleep: sleep
• slowpaste: Paste
• sorendition: Sorendition
• source: Source
• split: Split
• startup_message: Startup Message
• stuff: Paste
• su: Su
• suspend: Suspend
• term: Term
• termcap: Termcap Syntax
• termcapinfo: Termcap Syntax
• terminfo: Termcap Syntax
• time: Time
• title: Title Command
• umask: Umask
• unsetenv: Setenv
• utf8: Character Processing
• vbell: Bell
• vbell_msg: Bell
• vbellwait: Bell
• verbose: Verbose
• version: Version
• wall: Wall
• width: Window Size
• windowlist: Windowlist
• windows: Windows
• wrap: Wrap
• writebuf: Screen Exchange
• writelock: Writelock
• xoff: XON/XOFF
• xon: XON/XOFF
• zmodem: Zmodem
• zombie: Zombie

Keystroke Index

This is a list of the default key bindings.

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

• ": Windowlist
• ': Select
• *: Displays
• .: Dump Termcap
• 0...9: Select
• :: Colon
• <: Screen Exchange
• =: Screen Exchange
• >: Screen Exchange
• ?: Help
• [: Copy
• ]: Paste
• a: Command Character
• A: Title Command
• C: Clear
• c: Screen Command
• C-[: Copy
• C-\: Quit
• C-]: Paste
• C-a: Other Window
• C-c: Screen Command
• C-d: Detach
• C-f: Flow
• C-g: Bell
• C-h: Hardcopy
• C-i: Info
• C-k: Kill
• C-l: Redisplay
• C-m: Last Message
• C-n: Next and Previous
• C-p: Next and Previous
• C-q: XON/XOFF
• C-r: Wrap
• C-s: XON/XOFF
• C-t: Time
• C-v: Digraph
• C-w: Windows
• C-x: Lock
• C-z: Suspend
• D: Power Detach
• d: Detach
• ESC: Copy
• f: Flow
• F: Fit
• H: Log
• h: Hardcopy
• i: Info
• k: Kill
• l: Redisplay
• L: Login
• m: Last Message
• M: Monitor
• N: Number
• n: Next and Previous
• p: Next and Previous
• q: XON/XOFF
• Q: Only
• r: Wrap
• s: XON/XOFF
• S: Split
• SPC: Next and Previous
• t: Time
• TAB: Focus
• v: Version
• W: Window Size
• w: Windows
• X: Remove
• x: Lock
• Z: Reset
• z: Suspend
• {: History