Screen User’s Manual

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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. Shells usually distinguish between running as login-shell or sub-shell. Screen runs them as sub-shells, unless told otherwise (See shell .screenrc command).

Everything you type is sent to the program running in the current window. The only exception to this is the one keystroke that is used to initiate a command to the window manager. By default, each command begins with a control-a (abbreviated C-a from now on), and is followed by one other keystroke. The command character (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, although this notation is used in this manual for readability. Please use the caret notation ( ^A instead of C-a ) as arguments to e.g. the escape command or the -e option. Screen will also print out control characters in caret notation.

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

screen emacs prog.c

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

If /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 of xterm ). ‘ -c file ’ Use file as the user’s configuration file instead of the default of $HOME/.screenrc . ‘ -d [ pid.sessionname ] ’ ‘ -D [ pid.sessionname ] ’ Do not start screen , but instead detach a screen session running elsewhere (see 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 a screen session, this option sets the default command character. In a multiuser session all users added will start off with this command character. But when attaching to an already running session, this option 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. ‘ -Logfile "file" ’ By default logfile name is "screenlog.0". You can set new logfile name with the -Logfile option. ‘ -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. ‘ -O ’ Select a more optimal output mode for your terminal rather than true VT100 emulation (only affects auto-margin terminals without ‘ LP ’). This can also be set in your .screenrc by specifying ‘ OP ’ in the termcap command. ‘ -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, while a ‘ + ’ will create new window. The command will not be executed if the specified window could not be found. ‘ -q ’ Suppress printing of error messages. In combination with ‘ -ls ’ the exit value is 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. ‘ -Q ’ Some commands now can be queried from a remote session using this flag, e.g. ’screen -Q windows’. The commands will send the response to the stdout of the querying process. If there was an error in the command, then the querying process will exit with a non-zero status. The commands that can be queried now are: echo info lastmsg number select time title windows ‘ -r [ pid.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 screen sessions. The second form is used to connect to another user’s screen session which runs in multiuser mode. This indicates that screen should look for sessions in another user’s directory. This requires setuid-root. ‘ -R ’ resumes screen only when it’s unambiguous which one to attach, usually when only one screen is detached. Otherwise lists available sessions. ‘ -RR ’ 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). See also there. ‘ -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 -r commands. 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). ‘ -T term ’ Set the $TERM enviroment variable using the specified term as opposed to the default setting of screen . ‘ -U ’ Run screen in UTF-8 mode. This option tells screen that your terminal sends and understands UTF-8 encoded characters. It also sets the default encoding for new windows to ‘ utf8 ’. ‘ -v ’ Print 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 may use the -S option to specify the screen session if you have several running. You can use the -d or -r option to tell screen to look only for attached or detached screen sessions. Note that this command doesn’t work if the session is password protected.

4 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

Command: source file (none)

Read and execute commands from file file . Source commands may be nested to a maximum recursion level of ten. If file is not an absolute path and screen is already processing a source command, the parent directory of the running source command file is used to search for the new command file before screen’s current directory. Note that termcap/terminfo/termcapinfo commands only work at startup and reattach time, so they must be reached via the default screenrc files to have an effect.

4.3 Colon

Customization can also be done online, with this command:

Command: colon ( C-a : )

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

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:

5.2 Command Summary

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 is assigned to it. The number of windows is limited at compile-time by the MAXWIN configuration parameter (which defaults to 40).

• 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. • Window Groups: Grouping windows together

6.1 Chdir

Command: chdir [directory] (none)

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

6.2 Screen Command

Command: screen [opts] [n] [cmd [args] | //group ] ( C-a c , C-a C-c )

Establish a new window. The flow-control options (‘ -f ’, ‘ -fn ’ and ‘ -fa ’), title option (‘ -t ’), login options (‘ -l ’ and ‘ -ln ’) , terminal type option (‘ -T term ’), the all-capability-flag (‘ -a ’) and scrollback option (‘ -h num ’) may be specified with each command. The option (‘ -M ’) turns monitoring on for this window. The option (‘ -L ’) turns output logging on for this window. If an optional number n in the range 0…MAXWIN-1 is given, the window number n is assigned to the newly created window (or, if this number is already in-use, the next available number). If a command is specified after screen , this command (with the given arguments) is started in the window; otherwise, a shell is created. If ‘ //group ’ is supplied, a container-type window is created in which other windows may be created inside it. See Window Groups. Screen has built in some functionality of ‘ cu ’ and ‘ telnet ’. See Window Types.

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

Command: setenv var string (none)

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

Command: unsetenv var (none)

Unset an environment variable.

6.4 Shell

Command: shell command Command: defshell command (none)

Set the command to be used to create a new shell. This overrides the value of the environment variable $SHELL . This is useful if you’d like to run a tty-enhancer which is expecting to execute the program specified in $SHELL . If the command begins with a ‘ - ’ character, the shell will be started as a login-shell. Typical shells do only minimal initialization when not started as a login-shell. E.g. Bash will not read your ~/.bashrc unless it is a login-shell. defshell is currently a synonym to the shell .screenrc command.

Command: shelltitle title (none)

Set the title for all shells created during startup or by the C-a C-c command. See Naming Windows, for details about what titles are.

6.5 Term

Command: term term (none)

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

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...).

’, 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.

’) is specified as the first parameter, then the window is directly connected to this device. This window type is similar to ‘ ’. 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 ‘ ’: 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.

6.7 Window Groups

Screen provides a method for grouping windows together. Windows can be organized in a hierarchical fashion, resembling a tree structure. New screens are created using the screen command while new groups are created using screen //group . See Screen Command.

Once a new group is created, it will act as a container for windows and even other groups. When a group is selected, you will see the output of the windowlist command, allowing you to select a window inside. If there are no windows inside a group, use the screen command to create one. Once inside a group, using the commands next and prev will switch between windows only in that group. Using the windowlist command will give you the opportunity to leave the group you are in. See Windowlist.

Command: group [grouptitle] (none)

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

Using groups in combination with layouts will help create a multi-desktop experience. One group can be assigned for each layout made. Windows can be made, split, and organized within each group as desired. Afterwhich, switching between groups can be as easy as switching layouts.

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

Command: next ( C-a SPC , C-a n , C-a C-n )

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

Command: prev ( C-a p , C-a C-p , C-a C-h , C-a Backspace )

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

7.2 Other Window

Command: other ( C-a C-a )

Switch to the last window displayed. Note that this command defaults to the command character typed twice, unless overridden. For instance, if you use the option ‘ -e]x ’, this command becomes ]] (see Command Character).

7.3 Select

Command: select [n |-|. ] ( C-a n , C-a ' )

Switch to the window with the number n . If no window number is specified, you get prompted for an identifier. This can be a window name (title) or a number. When a new window is established, the lowest available number is assigned to this window. Thus, the first window can be activated by select 0 ; there can be no more than 10 windows present simultaneously (unless screen is compiled with a higher MAXWIN setting). There are two special arguments, select - switches to the internal blank window and select . switches to the current window. The latter is useful if used with screen’s -X option.

7.4 Windowlist

Command: windowlist [-b] [-m] [-g] Command: windowlist string [ string ] Command: windowlist title [ title ] ( C-a " )

Display all windows in a table for visual window selection. If screen was in a window group, screen will back out of the group and then display the windows in that group. If the -b option is given, screen will switch to the blank window before presenting the list, so that the current window is also selectable. The -m option changes the order of the windows, instead of sorting by window numbers screen uses its internal most-recently-used list. The -g option will show the windows inside any groups in that level and downwards. The following keys are used to navigate in windowlist : k , C-p , or up Move up one line. j , C-n , or down Move down one line. C-g or escape Exit windowlist. C-a or home Move to the first line. C-e or end Move to the last line. C-u or C-d Move one half page up or down. C-b or C-f Move one full page up or down. 0..9 Using the number keys, move to the selected line. mouseclick Move to the selected line. Available when mousetrack is set to on . / Search. n Repeat search in the forward direction. N Repeat search in the backward direction. m Toggle MRU. g Toggle group nesting. a All window view. C-h or backspace Back out the group. , Switch numbers with the previous window. . Switch numbers with the next window. K Kill that window. space or enter Select that window. The table format can be changed with the string and title option, the title is displayed as table heading, while the lines are made by using the string setting. The default setting is ‘ Num Name%=Flags ’ for the title and ‘ %3n %t%=%f ’ for the lines. See the string escapes chapter (see String Escapes) for more codes (e.g. color settings). Windowlist needs a region size of at least 10 characters wide and 6 characters high in order to display.

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

Command: autodetach state (none)

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

Command: detach ( C-a d , C-a C-d )

Detach the screen session (disconnect it from the terminal and put it into the background). A detached screen can be resumed by invoking screen with the -r option (see Invoking Screen). The -h option tells screen to immediately close the connection to the terminal (‘ hangup ’).

Command: password [crypted_pw] (none)

Present a crypted password in your .screenrc file and screen will ask for it, whenever someone attempts to resume a detached session. This is useful, if you have privileged programs running under screen and you want to protect your session from reattach attempts by users that managed to assume your uid. (I.e. any superuser.) If no crypted password is specified, screen prompts twice a password and places its encryption in the paste buffer. Default is ‘none’, which disables password checking.

8.2 Power Detach

Command: pow_detach ( C-a D D )

Mainly the same as detach , but also sends a HANGUP signal to the parent process of screen .

Caution: This will result in a logout if screen was started from your login-shell.

Command: pow_detach_msg [message] (none)

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

8.3 Lock

Command: lockscreen ( C-a x , C-a C-x )

Call a screenlock program ( /local/bin/lck or /usr/bin/lock or a builtin, if no other is available). Screen does not accept any command keys until this program terminates. Meanwhile processes in the windows may continue, as the windows are in the detached state. The screenlock program may be changed through the environment variable $LOCKPRG (which must be set in the shell from which screen is started) and is executed with the user’s uid and gid. Warning: When you leave other shells unlocked and have no password set on screen , the lock is void: One could easily re-attach from an unlocked shell. This feature should rather be called lockterminal .

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

Command: multiuser state (none)

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

8.4.2 Acladd

Command: acladd usernames Command: addacl usernames (none)

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

8.4.3 Aclchg

Command: aclchg usernames permbits list Command: chacl usernames permbits list (none)

Change permissions for a comma separated list of users. Permission bits are represented as ‘ r ’, ‘ w ’ and ‘ x ’. Prefixing ‘ + ’ grants the permission, ‘ - ’ removes it. The third parameter is a comma separated list of commands or windows (specified either by number or title). The special list ‘ # ’ refers to all windows, ‘ ? ’ to all commands. If usernames consists of a single ‘ * ’, all known users are affected. A command can be executed when the user has the ‘ x ’ bit for it. The user can type input to a window when he has its ‘ w ’ bit set and no other user obtains a writelock for this window. Other bits are currently ignored. To withdraw the writelock from another user in e.g. window 2: ‘ aclchg username -w+w 2 ’. To allow read-only access to the session: ‘ aclchg username -w "#" ’. As soon as a user’s name is known to screen, he can attach to the session and (per default) has full permissions for all command and windows. Execution permission for the acl commands, at and others should also be removed or the user may be able to regain write permission. Chacl is a synonym to aclchg . Multi-user mode only.

8.4.4 Acldel

Command: acldel username (none)

Remove a user from screen’s access control list. If currently attached, all the user’s displays are detached from the session. He cannot attach again. Multi-user mode only.

8.4.5 Aclgrp

Command: aclgrp username [ groupname ] (none)

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

8.4.6 Displays

Command: displays ( C-a * )

Shows a tabular listing of all currently connected user front-ends (displays). This is most useful for multiuser sessions. The following keys can be used in displays list: k , C-p , or up Move up one line. j , C-n , or down Move down one line. C-a or home Move to the first line. C-e or end Move to the last line. C-u or C-d Move one half page up or down. C-b or C-f Move one full page up or down. mouseclick Move to the selected line. Available when mousetrack is set to on . space Refresh the list. d Detach the selected display. D Power detach the selected display. C-g , enter , or escape Exit the list. The following is an example of what displays could look like: xterm 80x42 jnweiger@/dev/ttyp4 0(m11) &rWx facit 80x24 mlschroe@/dev/ttyhf nb 11(tcsh) rwx xterm 80x42 jnhollma@/dev/ttyp5 0(m11) &R.x (A) (B) (C) (D) (E) (F)(G) (H)(I) The legend is as follows:

(A) The terminal type known by screen for this display.

(B) Displays geometry as width x height.

(C) Username who is logged in at the display.

(D) Device name of the display or the attached device

(E) Display is in blocking or nonblocking mode. The available modes are "nb", "NB", "Z<", "Z>", and "BL".

(F) Number of the window

(G) Name/title of window

(H) Whether the window is shared

(I) Window permissions. Made up of three characters: (1st character) ‘ - ’ : no read ‘ r ’ : read ‘ R ’ : read only due to foreign wlock (2nd character) ‘ - ’ : no write ‘ . ’ : write suppressed by foreign wlock ‘ w ’ : write ‘ W ’ : own wlock (3rd character) ‘ - ’ : no execute ‘ x ’ : execute Displays needs a region size of at least 10 characters wide and 5 characters high in order to display.

8.4.7 aclumask

Command: aclumask [ users ]+/- bits ... Command: umask [ users ]+/- bits ... (none)

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

8.4.8 Wall

Command: wall message (none)

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

8.4.9 Writelock

Command: writelock on|off|auto (none)

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

Command: defwritelock on|off|auto (none)

Sets the default writelock behavior for new windows. Initially all windows will be created with no writelocks.

8.4.10 Su

Command: su [ username [ password [ password2 ]]] (none)

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

8.5 Session Name

Command: sessionname [ name ] (none)

Rename the current session. Note that for screen -list the name shows up with the process-id prepended. If the argument name is omitted, the name of this session is displayed.

Caution: The $STY environment variable will still reflect the old name in pre-existing shells. This may result in confusion. Use of this command is generally discouraged. Use the -S command-line option if you want to name a new session.The default is constructed from the tty and host names.

8.6 Suspend

Command: suspend ( C-a z , C-a C-z )

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

8.7 Quit

Command: quit ( C-a \ )

Kill all windows and terminate screen . (see Key Binding).

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 • Focusminsize: Force a minimum size on a current region • Layout: Manage groups of regions

9.1 Split

Command: split [-v] ( C-a S , C-a | )

Split the current region into two new ones. All regions on the display are resized to make room for the new region. The blank window is displayed in the new region. The default is to create a horizontal split, putting the new regions on the top and bottom of each other. Using ‘ -v ’ will create a vertical split, causing the new regions to appear side by side of each other. Use the remove or the only command to delete regions. Use focus to toggle between regions. When a region is split opposite of how it was previously split (that is, vertical then horizontal or horizontal then vertical), a new layer is created. The layer is used to group together the regions that are split the same. Normally, as a user, you should not see nor have to worry about layers, but they will affect how some commands ( focus and resize ) behave. With this current implementation of screen , scrolling data will appear much slower in a vertically split region than one that is not. This should be taken into consideration if you need to use system commands such as cat or tail -f .

9.2 Focus

Command: focus [ next|prev|up|down|left|right|top|bottom ] ( C-a Tab )

Move the input focus to the next region. This is done in a cyclic way so that the top left region is selected after the bottom right one. If no option is given it defaults to next . The next region to be selected is determined by how the regions are layered. Normally, the next region in the same layer would be selected. However, if that next region contains one or more layers, the first region in the highest layer is selected first. If you are at the last region of the current layer, next will move the focus to the next region in the lower layer (if there is a lower layer). Prev cycles in the opposite order. See Split for more information about layers. The rest of the options ( up , down , left , right , top , and bottom ) are more indifferent to layers. The option up will move the focus upward to the region that is touching the upper left corner of the current region. Down will move downward to the region that is touching the lower left corner of the current region. The option left will move the focus leftward to the region that is touching the upper left corner of the current region, while right will move rightward to the region that is touching the upper right corner of the current region. Moving left from a left most region or moving right from a right most region will result in no action. The option top will move the focus to the very first region in the upper list corner of the screen, and bottom will move to the region in the bottom right corner of the screen. Moving up from a top most region or moving down from a bottom most region will result in no action. Useful bindings are (h, j, k, and l as in vi): bind h focus left bind j focus down bind k focus up bind l focus right bind t focus top bind b focus bottom Note that ‘ k ’ is traditionally bound to the kill command.

9.3 Only

Command: only ( C-a Q )

Kill all regions but the current one.

9.4 Remove

Command: remove ( C-a X )

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

9.5 Resize

Command: resize [ -h|-v|-b|-l|-p ] [ [+|-] n [ % ] | = | max | min | _ | 0 ] (none)

Resize the current region. The space will be removed from or added to the surrounding regions depending on the order of the splits. The available options for resizing are ‘ -h ’(horizontal), ‘ -v ’(vertical), ‘ -b ’(both), ‘ -l ’(local to layer), and ‘ -p ’(perpendicular). Horizontal resizes will add or remove width to a region, vertical will add or remove height, and both will add or remove size from both dimensions. Local and perpendicular are similar to horizontal and vertical, but they take in account of how a region was split. If a region’s last split was horizontal, a local resize will work like a vertical resize. If a region’s last split was vertical, a local resize will work like a horizontal resize. Perpendicular resizes work in opposite of local resizes. If no option is specified, local is the default. The amount of lines to add or remove can be expressed a couple of different ways. By specifying a number n by itself will resize the region by that absolute amount. You can specify a relative amount by prefixing a plus ‘ + ’ or minus ‘ - ’ to the amount, such as adding +n lines or removing -n lines. Resizing can also be expressed as an absolute or relative percentage by postfixing a percent sign ‘ % ’. Using zero ‘ 0 ’ is a synonym for min and using an underscore ‘ _ ’ is a synonym for max . Some examples are: resize +N increase current region by N resize -N decrease current region by N resize N set current region to N resize 20% set current region to 20% of original size resize +20% increase current region by 20% resize -b = make all windows equally resize max maximize current region resize min minimize current region Without any arguments, screen will prompt for how you would like to resize the current region. See focusminsize if you want to restrict the minimun size a region can have.

9.6 Caption

Command: caption always | splitonly [string] Command: caption string [string] (none)

This command controls the display of the window captions. Normally a caption is only used if more than one window is shown on the display (split screen mode). But if the type is set to always , screen shows a caption even if only one window is displayed. The default is ‘ splitonly ’. The second form changes the text used for the caption. You can use all string escapes (see String Escapes). Screen uses a default of ‘ %3n %t ’. You can mix both forms by providing the string as an additional argument.

9.7 Fit

Command: fit ( C-a F )

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

9.8 Focusminsize

Command: focusminsize [ (width| max | _ ) (height| max | _ ) ] (none)

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

9.9 Layout

Using regions, and perhaps a large enough terminal, you can give screen more of a desktop feel. By being able to split regions horizontally or vertically, you can take advantage of the lesser used spaces of your terminal. The catch to these splits has been that they’re not kept between screen detachments and reattachments.

Layouts will help organize your regions. You can create one layout of four horizontal regions and then create a separate layout of regions in a two by two array. The regions could contain the same windows, but they don’t have to. You can easily switch between layouts and keep them between detachments and reattachments.

Note that there are several subcommands to layout .

Command: layout new [title] (none)

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

Command: layout remove [n|title] (none)

Remove, or in other words, delete the specified layout. Either the number or the title can be specified. Without either specification, screen will remove the current layout. Removing a layout does not affect your set windows or regions.

Command: layout next (none)

Switch to the next layout available

Command: layout prev (none)

Switch to the previous layout available

Command: layout select [n|title] (none)

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

Command: layout show (none)

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

Command: layout title [title] (none)

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

Command: layout number [n] (none)

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

Command: layout attach [title| :last ] (none)

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

Command: layout save [n|title] (none)

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

Command: layout autosave [ on | off ] (none)

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

Command: layout dump [filename] (none)

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

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 or inactivity 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

Command: title [windowtitle] ( C-a A )

Set the name of the current window to windowtitle . If no name is specified, screen prompts for one.

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 search portion of the title. Once this is set up, screen will use the title-escape-sequence to clear the previous command name and get ready for the next command. Then, when a newline is received from the shell, a search is made for the end of the prompt. If found, it will grab the first word after the matched string and use it as the command name. If the command name begins with ‘ ! ’, ‘ % ’, or ‘ ^ ’, screen will use the first word on the following line (if found) in preference to the just-found name. This helps csh users get more accurate titles when using job control or history recall commands.

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

Command: console [ state ] (none)

Grabs or un-grabs the machines console output to a window. When the argument is omitted the current state is displayed. Note: Only the owner of /dev/console can grab the console output. This command is only available if the host supports the ioctl TIOCCONS .

10.3 Kill

Command: kill ( C-a k , C-a C-k )

Kill the current window.

If there is an exec command running (see Exec) then it is killed. Otherwise the process (e.g. shell) running in the window receives a HANGUP condition, the window structure is removed and screen (your display) switches to another window. When the last window is destroyed, screen exits. After a kill screen switches to the previously displayed window.

Caution: emacs users may find themselves killing their emacs session when trying to delete the current line. For this reason, it is probably wise to use a different command character (see Command Character) or rebind kill to another key sequence, such as C-a K (see Key Binding).

10.4 Login

Command: deflogin state (none)

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

Command: login [state] ( C-a L )

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

10.5 Mode

Command: defmode mode (none)

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

10.6 Monitoring

Command: activity message (none)

When any activity occurs in a background window that is being monitored, screen displays a notification in the message line. The notification message can be redefined by means of the activity command. Each occurrence of ‘ % ’ in message is replaced by the number of the window in which activity has occurred, and each occurrence of ‘ ^G ’ is replaced by the definition for bell in your termcap (usually an audible bell). The default message is 'Activity in window %n' Note that monitoring is off for all windows by default, but can be altered by use of the monitor command ( C-a M ).

Command: defmonitor state (none)

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

Command: monitor [state] ( C-a M )

Toggles monitoring of the current window. When monitoring is turned on and the affected window is switched into the background, the activity notification message will be displayed in the status line at the first sign of output, and the window will also be marked with an ‘ @ ’ in the window-status display (see Windows). Monitoring defaults to ‘ off ’ for all windows.

Command: silence [ state | sec ] ( C-a _ )

Toggles silence monitoring of windows. When silence is turned on and an affected window is switched into the background, you will receive the silence notification message in the status line after a specified period of inactivity (silence). The default timeout can be changed with the silencewait command or by specifying a number of seconds instead of on or off . Silence is initially off for all windows.

Command: defsilence state (none)

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

Command: silencewait seconds (none)

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

10.7 Windows

Command: windows [ string ] ( C-a w , C-a C-w )

Uses the message line to display a list of all the windows. Each window is listed by number with the name of the program running in the window (or its title). The current window is marked with a ‘ * ’; the previous window is marked with a ‘ - ’; all the windows that are logged in are marked with a ‘ $ ’ (see Login); a background window that has received a bell is marked with a ‘ ! ’; a background window that is being monitored and has had activity occur is marked with an ‘ @ ’ (see Monitor); a window which has output logging turned on is marked with ‘ (L) ’; windows occupied by other users are marked with ‘ & ’ or ‘ && ’ if the window is shared by other users; windows in the zombie state are marked with ‘ Z ’. If this list is too long to fit on the terminal’s status line only the portion around the current window is displayed. You can customize the output format to any string you like including string escapes (see String Escapes). In this case, if the string parameter is passed, the maximum output size is unlimited (instead of 1024 bytes if no parameter is passed).

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.

Command: defhstatus [status] (none)

The hardstatus line that all new windows will get is set to status . This command is useful to make the hardstatus of every window display the window number or title or the like. status may contain the same directives as in the window messages, but the directive escape character is ‘ ^E ’ (octal 005) instead of ‘ % ’. This was done to make a misinterpretation of program generated hardstatus lines impossible. If the parameter status is omitted, the current default string is displayed. Per default the hardstatus line of new windows is empty.

Command: hstatus status (none)

Changes the current window’s hardstatus line to status .

10.9 Mousetrack

Command: mousetrack [ on|off ] (none)

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

Command: defmousetrack on|off (none)

This command determines the default state of the mousetrack command, currently defaulting of off .

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.

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 command stuff , 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

Command: digraph [preset [unicode-value]] ( C-a C-v )

This command prompts the user for a digraph sequence. The next two characters typed are looked up in a builtin table and the resulting character is inserted in the input stream. For example, if the user enters ‘ a" ’, an a-umlaut will be inserted. If the first character entered is a 0 (zero), screen will treat the following characters (up to three) as an octal number instead. The optional argument preset is treated as user input, thus one can create an "umlaut" key. For example the command ‘ bindkey ^K digraph '"' ’ enables the user to generate an a-umlaut by typing ‘ CTRL-K a ’. When a non-zero unicode-value is specified, a new digraph is created with the specified preset. The digraph is unset if a zero value is provided for the unicode-value . The following table is the builtin sequences. Sequence Octal Digraph Unicode Equivalent ----------------------------------------------- ' ', ' ' 160 (space) U+00A0 'N', 'S' 160 (space) U+00A0 '~', '!' 161 ¡ U+00A1 '!', '!' 161 ¡ U+00A1 '!', 'I' 161 ¡ U+00A1 'c', '|' 162 ¢ U+00A2 'c', 't' 162 ¢ U+00A2 '$', '$' 163 £ U+00A3 'P', 'd' 163 £ U+00A3 'o', 'x' 164 € U+00A4 'C', 'u' 164 € U+00A4 'C', 'u' 164 € U+00A4 'E', 'u' 164 € U+00A4 'Y', '-' 165 ¥ U+00A5 'Y', 'e' 165 ¥ U+00A5 '|', '|' 166 Š U+00A6 'B', 'B' 166 Š U+00A6 'p', 'a' 167 § U+00A7 'S', 'E' 167 § U+00A7 '"', '"' 168 š U+00A8 ''', ':' 168 š U+00A8 'c', 'O' 169 © U+00A9 'C', 'o' 169 © U+00A9 'a', '-' 170 ª U+00AA '<', '<' 171 « U+00AB '-', ',' 172 ¬ U+00AC 'N', 'O' 172 ¬ U+00AC '-', '-' 173 ­ U+00AD 'r', 'O' 174 ® U+00AE 'R', 'g' 174 ® U+00AE '-', '=' 175 ¯ U+00AF ''', 'm' 175 ¯ U+00AF '~', 'o' 176 ° U+00B0 'D', 'G' 176 ° U+00B0 '+', '-' 177 ± U+00B1 '2', '2' 178 ² U+00B2 '2', 'S' 178 ² U+00B2 '3', '3' 179 ³ U+00B3 '3', 'S' 179 ³ U+00B3 ''', ''' 180 Ž U+00B4 'j', 'u' 181 µ U+00B5 'M', 'y' 181 µ U+00B5 'p', 'p' 182 ¶ U+00B6 'P', 'I' 182 ¶ U+00B6 '~', '.' 183 · U+00B7 '.', 'M' 183 · U+00B7 ',', ',' 184 ž U+00B8 ''', ',' 184 ž U+00B8 '1', '1' 185 ¹ U+00B9 '1', 'S' 185 ¹ U+00B9 'o', '-' 186 º U+00BA '>', '>' 187 » U+00BB '1', '4' 188 Œ U+00BC '1', '2' 189 œ U+00BD '3', '4' 190 Ÿ U+00BE '~', '?' 191 ¿ U+00BF '?', '?' 191 ¿ U+00BF '?', 'I' 191 ¿ U+00BF 'A', '`' 192 À U+00C0 'A', '!' 192 À U+00C0 'A', ''' 193 Á U+00C1 'A', '^' 194 Â U+00C2 'A', '>' 194 Â U+00C2 'A', '~' 195 Ã U+00C3 'A', '?' 195 Ã U+00C3 'A', '"' 196 Ä U+00C4 'A', ':' 196 Ä U+00C4 'A', '@' 197 Å U+00C5 'A', 'A' 197 Å U+00C5 'A', 'E' 198 Æ U+00C6 'C', ',' 199 Ç U+00C7 'E', '`' 200 È U+00C8 'E', '!' 200 È U+00C8 'E', ''' 201 É U+00C9 'E', '^' 202 Ê U+00CA 'E', '>' 202 Ê U+00CA 'E', '"' 203 Ë U+00CB 'E', ':' 203 Ë U+00CB 'I', '`' 204 Ì U+00CC 'I', '!' 204 Ì U+00CC 'I', ''' 205 Í U+00CD 'I', '^' 206 Î U+00CE 'I', '>' 206 Î U+00CE 'I', '"' 207 Ï U+00CF 'I', ':' 207 Ï U+00CF 'D', '-' 208 Ð U+00D0 'N', '~' 209 Ñ U+00D1 'N', '?' 209 Ñ U+00D1 'O', '`' 210 Ò U+00D2 'O', '!' 210 Ò U+00D2 'O', ''' 211 Ó U+00D3 'O', '^' 212 Ô U+00D4 'O', '>' 212 Ô U+00D4 'O', '~' 213 Õ U+00D5 'O', '?' 213 Õ U+00D5 'O', '"' 214 Ö U+00D6 'O', ':' 214 Ö U+00D6 '/', '\' 215 × U+00D7 '*', 'x' 215 × U+00D7 'O', '/' 216 Ø U+00D8 'U', '`' 217 Ù U+00D9 'U', '!' 217 Ù U+00D9 'U', ''' 218 Ú U+00DA 'U', '^' 219 Û U+00DB 'U', '>' 219 Û U+00DB 'U', '"' 220 Ü U+00DC 'U', ':' 220 Ü U+00DC 'Y', ''' 221 Ý U+00DD 'I', 'p' 222 Þ U+00DE 'T', 'H' 222 Þ U+00DE 's', 's' 223 ß U+00DF 's', '"' 223 ß U+00DF 'a', '`' 224 à U+00E0 'a', '!' 224 à U+00E0 'a', ''' 225 á U+00E1 'a', '^' 226 â U+00E2 'a', '>' 226 â U+00E2 'a', '~' 227 ã U+00E3 'a', '?' 227 ã U+00E3 'a', '"' 228 ä U+00E4 'a', ':' 228 ä U+00E4 'a', 'a' 229 å U+00E5 'a', 'e' 230 æ U+00E6 'c', ',' 231 ç U+00E7 'e', '`' 232 è U+00E8 'e', '!' 232 è U+00E8 'e', ''' 233 é U+00E9 'e', '^' 234 ê U+00EA 'e', '>' 234 ê U+00EA 'e', '"' 235 ë U+00EB 'e', ':' 235 ë U+00EB 'i', '`' 236 ì U+00EC 'i', '!' 236 ì U+00EC 'i', ''' 237 í U+00ED 'i', '^' 238 î U+00EE 'i', '>' 238 î U+00EE 'i', '"' 239 ï U+00EF 'i', ':' 239 ï U+00EF 'd', '-' 240 ð U+00F0 'n', '~' 241 ñ U+00F1 'n', '?' 241 ñ U+00F1 'o', '`' 242 ò U+00F2 'o', '!' 242 ò U+00F2 'o', ''' 243 ó U+00F3 'o', '^' 244 ô U+00F4 'o', '>' 244 ô U+00F4 'o', '~' 245 õ U+00F5 'o', '?' 245 õ U+00F5 'o', '"' 246 ö U+00F6 'o', ':' 246 ö U+00F6 ':', '-' 247 ÷ U+00F7 'o', '/' 248 ø U+00F8 'u', '`' 249 ù U+00F9 'u', '!' 249 ù U+00F9 'u', ''' 250 ú U+00FA 'u', '^' 251 û U+00FB 'u', '>' 251 û U+00FB 'u', '"' 252 ü U+00FC 'u', ':' 252 ü U+00FC 'y', ''' 253 ý U+00FD 'i', 'p' 254 þ U+00FE 't', 'h' 254 þ U+00FE 'y', '"' 255 ÿ U+00FF 'y', ':' 255 ÿ U+00FF '"', '[' 196 Ä U+00C4 '"', '\' 214 Ö U+00D6 '"', ']' 220 Ü U+00DC '"', '{' 228 ä U+00E4 '"', '|' 246 ö U+00F6 '"', '}' 252 ü U+00FC '"', '~' 223 ß U+00DF

11.4 Bell

Command: bell_msg [message] (none)

When a bell character is sent to a background window, screen displays a notification in the message line. The notification message can be re-defined by this command. Each occurrence of ‘ % ’ in message is replaced by the number of the window to which a bell has been sent, and each occurrence of ‘ ^G ’ is replaced by the definition for bell in your termcap (usually an audible bell). The default message is 'Bell in window %n' An empty message can be supplied to the bell_msg command to suppress output of a message line ( bell_msg "" ). Without a parameter, the current message is shown.

Command: vbell [state] ( C-a C-g )

Sets or toggles the visual bell setting for the current window. If vbell is switched to ‘ on ’, but your terminal does not support a visual bell, the visual bell message is displayed in the status line when the bell character is received. Visual bell support of a terminal is defined by the termcap variable vb . See Bell, for more information on visual bells. The equivalent terminfo capability is flash . Per default, vbell is ‘ off ’, thus the audible bell is used.

Command: vbell_msg [message] (none)

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

Command: vbellwait sec (none)

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

11.5 Clear

Command: clear ( C-a C )

Clears the screen and saves its contents to the scrollback buffer.

11.6 Info

Command: info ( C-a i , C-a C-i )

Uses the message line to display some information about the current window: the cursor position in the form ‘ ( column , row ) ’ starting with ‘ (1,1) ’, the terminal width and height plus the size of the scrollback buffer in lines, like in ‘ (80,24)+50 ’, the current state of window XON/XOFF flow control is shown like this (see Flow Control): +flow automatic flow control, currently on. -flow automatic flow control, currently off. +(+)flow flow control enabled. Agrees with automatic control. -(+)flow flow control disabled. Disagrees with automatic control. +(-)flow flow control enabled. Disagrees with automatic control. -(-)flow flow control disabled. Agrees with automatic control. The current line wrap setting (‘ +wrap ’ indicates enabled, ‘ -wrap ’ not) is also shown. The flags ‘ ins ’, ‘ org ’, ‘ app ’, ‘ log ’, ‘ mon ’ and ‘ nored ’ are displayed when the window is in insert mode, origin mode, application-keypad mode, has output logging, activity monitoring or partial redraw enabled. The currently active character set (‘ G0 ’, ‘ G1 ’, ‘ G2 ’, or ‘ G3 ’), and in square brackets the terminal character sets that are currently designated as ‘ G0 ’ through ‘ G3 ’. If the window is in UTF-8 mode, the string ‘ UTF-8 ’ is shown instead. Additional modes depending on the type of the window are displayed at the end of the status line (see Window Types). If the state machine of the terminal emulator is in a non-default state, the info line is started with a string identifying the current state. For system information use time .

Command: dinfo (none)

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

11.7 Redisplay

Command: allpartial state (none)

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

Command: altscreen state (none)

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

Command: partial state (none)

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

Command: redisplay ( C-a l , C-a C-l )

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

11.8 Wrap

Command: wrap [ on | off ] ( C-a r , C-a C-r )

Sets the line-wrap setting for the current window. When line-wrap is on, the second consecutive printable character output at the last column of a line will wrap to the start of the following line. As an added feature, backspace (^H) will also wrap through the left margin to the previous line. Default is ‘ on ’. Without any options, the state of wrap is toggled.

Command: defwrap state (none)

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

11.9 Reset

Command: reset ( C-a Z )

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

11.10 Window Size

Command: width [ -w | -d ] [cols [lines]] ( C-a W )

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

Command: height [ -w | -d ] [lines [cols]] (none)

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

11.11 Character Processing

Command: c1 [state] (none)

Change c1 code processing. ‘ c1 on ’ tells screen to treat the input characters between 128 and 159 as control functions. Such an 8-bit code is normally the same as ESC followed by the corresponding 7-bit code. The default setting is to process c1 codes and can be changed with the ‘ defc1 ’ command. Users with fonts that have usable characters in the c1 positions may want to turn this off.

Command: gr [state] (none)

Turn GR charset switching on/off. Whenever screen sees an input char with an 8th bit set, it will use the charset stored in the GR slot and print the character with the 8th bit stripped. The default (see also ‘ defgr ’) is not to process GR switching because otherwise the ISO88591 charset would not work.

Command: bce [state] (none)

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

Command: encoding enc [denc] (none)

Tell screen how to interpret the input/output. The first argument sets the encoding of the current window. Each window can emulate a different encoding. The optional second parameter overwrites the encoding of the connected terminal. It should never be needed as screen uses the locale setting to detect the encoding. There is also a way to select a terminal encoding depending on the terminal type by using the ‘ KJ ’ termcap entry. See Special Capabilities. Supported encodings are eucJP , SJIS , eucKR , eucCN , Big5 , GBK , KOI8-R , CP1251 , UTF-8 , ISO8859-2 , ISO8859-3 , ISO8859-4 , ISO8859-5 , ISO8859-6 , ISO8859-7 , ISO8859-8 , ISO8859-9 , ISO8859-10 , ISO8859-15 , jis . See also ‘ defencoding ’, which changes the default setting of a new window.

Command: charset set (none)

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

Command: utf8 [state [dstate]] (none)

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

Command: defc1 state (none)

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

Command: defgr state (none)

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

Command: defbce state (none)

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

Command: defencoding enc (none)

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

Command: defcharset [set] (none)

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

Command: defutf8 state (none)

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

Command: cjkwidth [state] (none)

Toggle how ambiguoous characters are treated. If cjkwidth is on screen interprets them as double (full) width characters. If off then they are seen as one cell (half) width characters.

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

Command: copy ( C-a [ , C-a C-[ , C-a ESC )

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

• 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

Command: crlf [state] (none)

This affects the copying of text regions with the copy command. If it is set to ‘ on ’, lines will be separated by the two character sequence ‘ CR ’/‘ LF ’. Otherwise only ‘ LF ’ is used. crlf is off by default. When no parameter is given, the state is toggled.

12.1.2 Scrollback

To access and use the contents in the scrollback buffer, use the copy command. See Copy.

Command: defscrollback num (none)

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

Command: scrollback num (none)

Set the size of the scrollback buffer for the current window to num lines. The default scrollback is 100 lines. Use info to view the current setting.

Command: compacthist [state] (none)

This tells screen whether to suppress trailing blank lines when scrolling up text into the history buffer. Turn compacting ‘ on ’ to hold more useful lines in your scrollback buffer.

12.1.3 Markkeys

Command: markkeys string (none)

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

12.1.4 Movement Keys

h , C-h , or left arrow move the cursor left.

j , C-n , or down arrow move the cursor down.

k , C-p , or up arrow move the cursor up.

l (’el’), or right arrow move the cursor right.

0 (zero) or C-a move to the leftmost column.

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

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

| moves to the specified absolute column.

g or home moves to the beginning of the buffer.

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

% jumps to the specified percentage of the buffer.

^ or $ move to the first or last non-whitespace character on the line.

w , b , and e move the cursor word by word.

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

f / F , t / T move the cursor forward/backward to the next occurence of the target. (eg, ’3fy’ will move the cursor to the 3rd ’y’ to the right.)

; and , Repeat the last f/F/t/T command in the same/opposite direction.

C-e and C-y scroll the display up/down by one line while preserving the cursor position.

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

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

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 or enter to set the first or second mark respectively. If mousetrack is set to on , marks can also be set using left mouse click .

Y and y 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.

Command: ignorecase [on|off] (none)

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

n Repeat search in forward direction.

N Repeat search in backward direction.

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 or 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 or o (’oh’) exchanges the first mark and the current cursor position. You can use this to adjust an already placed mark.

C-l (’el’) will redraw the screen.

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

All keys not described here exit copy mode.

12.2 Paste

Command: paste [registers [destination]] ( C-a ] , C-a C-] )

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

Command: stuff [string] (none)

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

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

Command: slowpaste msec Command: defslowpaste msec (none)

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

Command: readreg [-e encoding] [register [filename]] (none)

Does one of two things, dependent on number of arguments: with zero or one arguments it it duplicates the paste buffer contents into the register specified or entered at the prompt. With two arguments it reads the contents of the named file into the register, just as readbuf reads the screen-exchange file into the paste buffer. You can tell screen the encoding of the file via the -e option. The following example will paste the system’s password file into the screen window (using register p, where a copy remains): C-a : readreg p /etc/passwd C-a : paste p

12.3 Registers

Command: copy_reg [key] (none)

Removed. Use readreg instead.

Command: ins_reg [key] (none)

Removed. Use paste instead.

Command: process [key] (none)

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

Command: register [-e encoding] key string (none)

Save the specified string to the register key . The encoding of the strin