This file documents the 'Screen' virtual terminal manager. Copyright (c) 1993-2017 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Foundation. Screen 1 Overview 2 Getting Started 3 Invoking 'Screen' 4 Customizing 'Screen' 5 Commands 6 New Window 7 Selecting a Window 8 Session Management Commands 9 Regions 10 Window Settings 11 Virtual Terminal 12 Copy and Paste 13 Subprocess Execution 14 Key Binding 15 Flow Control 16 Termcap 17 The Message Line 18 Logging 19 Startup 20 Miscellaneous commands 21 String Escapes 22 Environment Variables 23 Files Referenced 24 Credits 25 Bugs 26 Installation Concept Index Command Index Keystroke Index Screen 1 Overview 2 Getting Started 3 Invoking 'Screen' 4 Customizing 'Screen' 4.1 The '.screenrc' file 4.2 Source 4.3 Colon 5 Commands 5.1 Default Key Bindings 5.2 Command Summary 6 New Window 6.1 Chdir 6.2 Screen Command 6.3 Setenv 6.4 Shell 6.5 Term 6.6 Window Types 6.7 Window Groups 7 Selecting a Window 7.1 Moving Back and Forth 7.2 Other Window 7.3 Select 7.4 Windowlist 8 Session Management Commands 8.1 Detach 8.2 Power Detach 8.3 Lock 8.4 Multiuser Session 8.4.1 Multiuser 8.4.2 Acladd 8.4.3 Aclchg 8.4.4 Acldel 8.4.5 Aclgrp 8.4.6 Displays 8.4.7 aclumask 8.4.8 Wall 8.4.9 Writelock 8.4.10 Su 8.5 Session Name 8.6 Suspend 8.7 Quit 9 Regions 9.1 Split 9.2 Focus 9.3 Only 9.4 Remove 9.5 Resize 9.6 Caption 9.7 Fit 9.8 Focusminsize 9.9 Layout 10 Window Settings 10.1 Naming Windows (Titles) 10.1.1 Title Command 10.1.2 Dynamic Titles 10.1.3 Setting up your prompt for shell titles 10.1.4 Setting up shell titles in your '.screenrc' 10.2 Console 10.3 Kill 10.4 Login 10.5 Mode 10.6 Monitoring 10.7 Windows 10.8 Hardstatus 10.9 Mousetrack 11 Virtual Terminal 11.1 Control Sequences 11.2 Input Translation 11.3 Digraph 11.4 Bell 11.5 Clear 11.6 Info 11.7 Redisplay 11.8 Wrap 11.9 Reset 11.10 Window Size 11.11 Character Processing 12 Copy and Paste 12.1 Copying 12.1.1 CR/LF 12.1.2 Scrollback 12.1.3 Markkeys 12.1.4 Movement Keys 12.1.5 Marking 12.1.6 Repeat Count 12.1.7 Searching 12.1.8 Specials 12.2 Paste 12.3 Registers 12.4 Screen Exchange 12.5 History 13 Subprocess Execution 13.1 Exec 13.2 Using Exec 14 Key Binding 14.1 The 'bind' command 14.2 Examples of the 'bind' command 14.3 Command Character 14.4 Help 14.5 Bindkey 14.6 Bindkey Examples 14.7 Bindkey Control 15 Flow Control 15.1 About 'screen' flow control settings 15.2 Flow 15.3 XON and XOFF 16 Termcap 16.1 Choosing the termcap entry for a window 16.2 Write out the window's termcap entry 16.3 The 'termcap' command 16.4 Termcap Examples 16.5 Special Terminal Capabilities 16.6 Autonuke 16.7 Obuflimit 16.8 Character Translation 17 The Message Line 17.1 Using the message line from your program 17.2 Hardware Status Line 17.3 Display Last Message 17.4 Message Wait 18 Logging 18.1 hardcopy 18.2 log 19 Startup 19.1 echo 19.2 sleep 19.3 Startup Message 20 Miscellaneous commands 20.1 At 20.2 Break 20.3 Bumpleft 20.4 Bumpright 20.5 Collapse 20.6 Debug 20.7 License 20.8 Nethack 20.9 Nonblock 20.10 Number 20.11 Time 20.12 Verbose 20.13 Version 20.14 Zombie 20.15 Printcmd 20.16 Rendition 20.17 Sorendition 20.18 Attrcolor 20.19 Setsid 20.20 Eval 20.21 Maxwin 20.22 Backtick 20.23 Screen Saver 20.24 Zmodem 21 String Escapes 22 Environment Variables 23 Files Referenced 24 Credits 25 Bugs 25.1 Known Bugs 25.2 Reporting Bugs 25.3 Availability 26 Installation 26.1 Socket Directory 26.2 Compiling Screen Concept Index Command Index Keystroke Index Screen ****** This file documents the 'Screen' virtual terminal manager, version 4.6.2. 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 (*note Command Character::) and all the key bindings (*note 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. *Note 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 ?' (*note 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 (*note Default Key Bindings::). Another section (*note 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. *Note 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 (*note 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. (*note Command Character::). '-f' '-fn' '-fa' Set flow-control to on, off, or automatic switching mode, respectively. This option is equivalent to the 'defflow' command (*note Flow Control::). '-h NUM' Set the history scrollback buffer to be NUM lines high. Equivalent to the 'defscrollback' command (*note 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 (*note 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 (*note 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; *note 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 (*note 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 (*note 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 (*note Session Name::). '-t NAME' Set the title (name) for the default shell or specified program. This option is equivalent to the 'shelltitle' command (*note Shell::). '-T TERM' Set the $TERM enviroment variable using the specified _term_ as opposed to the default setting of 'screen'. '-U' Run screen in UTF-8 mode. This option tells screen that your terminal sends and understands UTF-8 encoded characters. It also sets the default encoding for new windows to 'utf8'. '-v' Print the version number. '-wipe [MATCH]' List available screens like 'screen -ls', but remove destroyed sessions instead of marking them as 'dead'. An unreachable session is considered dead, when its name matches either the name of the local host, or the explicitly given parameter, if any. See the '-r' flag for a description how to construct matches. '-x' Attach to a session which is already attached elsewhere (multi-display mode). 'Screen' refuses to attach from within itself. But when cascading multiple screens, loops are not detected; take care. '-X' Send the specified command to a running screen session. You may use the '-S' option to specify the screen session if you have several running. You can use the '-d' or '-r' option to tell screen to look only for attached or detached screen sessions. Note that this command doesn't work if the session is password protected. 4 Customizing 'Screen' ********************** You can modify the default settings for 'screen' to fit your tastes either through a personal '.screenrc' file which contains commands to be executed at startup, or on the fly using the 'colon' command. 4.1 The '.screenrc' file ======================== When 'screen' is invoked, it executes initialization commands from the files '.screenrc' in the user's home directory and '/usr/local/etc/screenrc'. These defaults can be overridden in the following ways: For the global screenrc file 'screen' searches for the environment variable '$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 (*note 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 (*note 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 (*note 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. 5.1 Default Key Bindings ======================== As mentioned previously, each keyboard command consists of a 'C-a' followed by one other character. For your convenience, all commands that are bound to lower-case letters are also bound to their control character counterparts (with the exception of 'C-a a'; see below). Thus, both 'C-a c' and 'C-a C-c' can be used to create a window. The following table shows the default key bindings: 'C-a '' (select) Prompt for a window identifier and switch. *Note Selecting::. 'C-a "' (windowlist -b) Present a list of all windows for selection. *Note Selecting::. 'C-a 0...9, -' (select 0...select 9, select -) Switch to window number 0...9, or the blank window. *Note Selecting::. 'C-a ' (focus) Switch the input focus to the next region. *Note Regions::. 'C-a C-a' (other) Toggle to the window displayed previously. If this window does no longer exist, 'other' has the same effect as 'next'. *Note Selecting::. 'C-a a' (meta) Send the command character (C-a) to window. See 'escape' command. *Note Command Character::. 'C-a A' (title) Allow the user to enter a title for the current window. *Note Naming Windows::. 'C-a b' 'C-a C-b' (break) Send a break to the tty. *Note Break::. 'C-a B' (pow_break) Close and reopen the tty-line. *Note Break::. 'C-a c' 'C-a C-c' (screen) Create a new window with a shell and switch to that window. *Note Screen Command::. 'C-a C' (clear) Clear the screen. *Note Clear::. 'C-a d' 'C-a C-d' (detach) Detach 'screen' from this terminal. *Note Detach::. 'C-a D D' (pow_detach) Detach and logout. *Note Power Detach::. 'C-a f' 'C-a C-f' (flow) Cycle flow among 'on', 'off' or 'auto'. *Note Flow::. 'C-a F' (fit) Resize the window to the current region size. *Note Fit::. 'C-a C-g' (vbell) Toggle visual bell mode. *Note Bell::. 'C-a h' (hardcopy) Write a hardcopy of the current window to the file "hardcopy.N". *Note Hardcopy::. 'C-a H' (log) Toggle logging of the current window to the file "screenlog.N". *Note Log::. 'C-a i' 'C-a C-i' (info) Show info about the current window. *Note Info::. 'C-a k' 'C-a C-k' (kill) Destroy the current window. *Note Kill::. 'C-a l' 'C-a C-l' (redisplay) Fully refresh the current window. *Note Redisplay::. 'C-a L' (login) Toggle the current window's login state. *Note Login::. 'C-a m' 'C-a C-m' (lastmsg) Repeat the last message displayed in the message line. *Note Last Message::. 'C-a M' (monitor) Toggle monitoring of the current window. *Note Monitor::. 'C-a ' 'C-a n' 'C-a C-n' (next) Switch to the next window. *Note Selecting::. 'C-a N' (number) Show the number (and title) of the current window. *Note Number::. 'C-a p' 'C-a C-p' 'C-a C-h' 'C-a ' (prev) Switch to the previous window (opposite of 'C-a n'). *Note Selecting::. 'C-a q' 'C-a C-q' (xon) Send a ^Q (ASCII XON) to the current window. *Note XON/XOFF::. 'C-a Q' (only) Delete all regions but the current one. *Note Regions::. 'C-a r' 'C-a C-r' (wrap) Toggle the current window's line-wrap setting (turn the current window's automatic margins on or off). *Note Wrap::. 'C-a s' 'C-a C-s' (xoff) Send a ^S (ASCII XOFF) to the current window. *Note XON/XOFF::. 'C-a S' (split) Split the current region horizontally into two new ones. *Note Regions::. 'C-a t' 'C-a C-t' (time) Show the load average and xref. *Note Time::. 'C-a v' (version) Display the version and compilation date. *Note Version::. 'C-a C-v' (digraph) Enter digraph. *Note Digraph::. 'C-a w' 'C-a C-w' (windows) Show a list of active windows. *Note Windows::. 'C-a W' (width) Toggle between 80 and 132 columns. *Note Window Size::. 'C-a x' 'C-a C-x' (lockscreen) Lock your terminal. *Note Lock::. 'C-a X' (remove) Kill the current region. *Note Regions::. 'C-a z' 'C-a C-z' (suspend) Suspend 'screen'. *Note Suspend::. 'C-a Z' (reset) Reset the virtual terminal to its "power-on" values. *Note Reset::. 'C-a .' (dumptermcap) Write out a '.termcap' file. *Note Dump Termcap::. 'C-a ?' (help) Show key bindings. *Note Help::. 'C-a \' (quit) Kill all windows and terminate 'screen'. *Note Quit::. 'C-a :' (colon) Enter a command line. *Note Colon::. 'C-a [' 'C-a C-[' 'C-a ' (copy) Enter copy/scrollback mode. *Note Copy::. 'C-a ]' 'C-a C-]' (paste .) Write the contents of the paste buffer to the stdin queue of the current window. *Note Paste::. 'C-a {' 'C-a }' (history) Copy and paste a previous (command) line. *Note History::. 'C-a >' (writebuf) Write the paste buffer out to the screen-exchange file. *Note Screen Exchange::. 'C-a <' (readbuf) Read the screen-exchange file into the paste buffer. *Note Screen Exchange::. 'C-a =' (removebuf) Delete the screen-exchange file. *Note Screen Exchange::. 'C-a _' (silence) Start/stop monitoring the current window for inactivity. *Note Monitor::. 'C-a |' (split -v) Split the current region vertically into two new ones. *Note Regions::. 'C-a ,' (license) Show the copyright page. *Note License::. 'C-a *' (displays) Show the listing of attached displays. *Note Displays::. 5.2 Command Summary =================== 'acladd USERNAMES' Allow other users in this session. *Note Multiuser Session::. 'aclchg USERNAMES PERMBITS LIST' Change a user's permissions. *Note Multiuser Session::. 'acldel USERNAME' Disallow other user in this session. *Note Multiuser Session::. 'aclgrp USRNAME [GROUPNAME]' Inherit permissions granted to a group leader. *Note Multiuser Session::. 'aclumask [USERS]+/-BITS ...' Predefine access to new windows. *Note Umask::. 'activity MESSAGE' Set the activity notification message. *Note Monitor::. 'addacl USERNAMES' Synonym to 'acladd'. *Note Multiuser Session::. 'allpartial STATE' Set all windows to partial refresh. *Note Redisplay::. 'altscreen STATE' Enables support for the "alternate screen" terminal capability. *Note Redisplay::. 'at [IDENT][#|*|%] COMMAND [ARGS]' Execute a command at other displays or windows. *Note At::. 'attrcolor ATTRIB [ATTRIBUTE/COLOR-MODIFIER]' Map attributes to colors. *Note Attrcolor::. 'autodetach STATE' Automatically detach the session on SIGHUP. *Note Detach::. 'autonuke STATE' Enable a clear screen to discard unwritten output. *Note Autonuke::. 'backtick ID LIFESPAN AUTOREFRESH COMMAND [ARGS]' Define a command for the backtick string escape. *Note Backtick::. 'bce [STATE]' Change background color erase. *Note Character Processing::. 'bell_msg [MESSAGE]' Set the bell notification message. *Note Bell::. 'bind [-c CLASS] KEY [COMMAND [ARGS]]' Bind a command to a key. *Note Bind::. 'bindkey [OPTS] [STRING [CMD ARGS]]' Bind a string to a series of keystrokes. *Note Bindkey::. 'blanker' Blank the screen. *Note Screen Saver::. 'blankerprg' Define a blanker program. *Note Screen Saver::. 'break [DURATION]' Send a break signal to the current window. *Note Break::. 'breaktype [TCSENDBREAK | TCSBRK | TIOCSBRK]' Specify how to generate breaks. *Note Break::. 'bufferfile [EXCHANGE-FILE]' Select a file for screen-exchange. *Note Screen Exchange::. 'bumpleft' Swaps window with previous one on window list. *Note Bumpleft::. 'bumpright' Swaps window with previous one on window list. *Note Bumpright::. 'c1 [STATE]' Change c1 code processing. *Note Character Processing::. 'caption MODE [STRING]' Change caption mode and string. *Note Regions::. 'chacl USERNAMES PERMBITS LIST' Synonym to 'aclchg'. *Note Multiuser Session::. 'charset SET' Change character set slot designation. *Note Character Processing::. 'chdir [DIRECTORY]' Change the current directory for future windows. *Note Chdir::. 'cjkwidth' Treat ambiguous width characters as full/half width. *Note Character Processing::. 'clear' Clear the window screen. *Note Clear::. 'colon' Enter a 'screen' command. *Note Colon::. 'collapse' Reorders window on window list, removing number gaps between them. *Note Collapse::. 'command [-c CLASS]' Simulate the screen escape key. *Note Command Character::. 'compacthist [STATE]' Selects compaction of trailing empty lines. *Note Scrollback::. 'console [STATE]' Grab or ungrab console output. *Note Console::. 'copy' Enter copy mode. *Note Copy::. 'copy_reg [KEY]' Removed. Use 'paste' instead. *Note Registers::. 'crlf STATE' Select line break behavior for copying. *Note Line Termination::. 'debug STATE' Suppress/allow debugging output. *Note Debug::. 'defautonuke STATE' Select default autonuke behavior. *Note Autonuke::. 'defbce STATE' Select background color erase. *Note Character Processing::. 'defbreaktype [TCSENDBREAK | TCSBRK | TIOCSBRK]' Specify the default for generating breaks. *Note Break::. 'defc1 STATE' Select default c1 processing behavior. *Note Character Processing::. 'defcharset [SET]' Change defaul character set slot designation. *Note Character Processing::. 'defencoding ENC' Select default window encoding. *Note Character Processing::. 'defescape XY' Set the default command and 'meta' characters. *Note Command Character::. 'defflow FSTATE' Select default flow control behavior. *Note Flow::. 'defgr STATE' Select default GR processing behavior. *Note Character Processing::. 'defhstatus [STATUS]' Select default window hardstatus line. *Note Hardstatus::. 'deflog STATE' Select default window logging behavior. *Note Log::. 'deflogin STATE' Select default utmp logging behavior. *Note Login::. 'defmode MODE' Select default file mode for ptys. *Note Mode::. 'defmonitor STATE' Select default activity monitoring behavior. *Note Monitor::. 'defmousetrack ON|OFF' Select the default mouse tracking behavior. *Note Mousetrack::. 'defnonblock STATE|NUMSECS' Select default nonblock mode. *Note Nonblock::. 'defobuflimit LIMIT' Select default output buffer limit. *Note Obuflimit::. 'defscrollback NUM' Set default lines of scrollback. *Note Scrollback::. 'defshell COMMAND' Set the default program for new windows. *Note Shell::. 'defsilence STATE' Select default idle monitoring behavior. *Note Monitor::. 'defslowpaste MSEC' Select the default inter-character timeout when pasting. *Note Paste::. 'defutf8 STATE' Select default character encoding. *Note Character Processing::. 'defwrap STATE' Set default line-wrapping behavior. *Note Wrap::. 'defwritelock ON|OFF|AUTO' Set default writelock behavior. *Note Multiuser Session::. 'zombie_timeout [SECONDS]' Try to reconnect dead windows after timeout. *Note Zombie::. 'detach [-h]' Disconnect 'screen' from the terminal. *Note Detach::. 'digraph [PRESET [UNICODE-VALUE]]' Enter a digraph sequence. *Note Digraph::. 'dinfo' Display terminal information. *Note Info::. 'displays' List currently active user interfaces. *Note Displays::. 'dumptermcap' Write the window's termcap entry to a file. *Note Dump Termcap::. 'echo [-n] MESSAGE' Display a message on startup. *Note Startup::. 'encoding ENC [DENC]' Set the encoding of a window. *Note Character Processing::. 'escape XY' Set the command and 'meta' characters. *Note Command Character::. 'eval COMMAND1 [COMMAND2 ...]' Parse and execute each argument. *Note Eval::. 'exec [[FDPAT] COMMAND [ARGS ...]]' Run a subprocess (filter). *Note Exec::. 'fit' Change window size to current display size. *Note Window Size::. 'flow [FSTATE]' Set flow control behavior. *Note Flow::. 'focus [next|prev|up|down|left|right|top|bottom]' Move focus to next region. *Note Regions::. 'focusminsize' Force the current region to a certain size. *Note Focusminsize::. 'gr [STATE]' Change GR charset processing. *Note Character Processing::. 'group [GROUPTITLE]' Change or show the group the current window belongs to. *Note Window Groups::. 'hardcopy [-h] [FILE]' Write out the contents of the current window. *Note Hardcopy::. 'hardcopy_append STATE' Append to hardcopy files. *Note Hardcopy::. 'hardcopydir DIRECTORY' Place, where to dump hardcopy files. *Note Hardcopy::. 'hardstatus [STATE]' Use the hardware status line. *Note Hardware Status Line::. 'height [LINES [COLS]]' Set display height. *Note Window Size::. 'help [-c CLASS]' Display current key bindings. *Note Help::. 'history' Find previous command beginning .... *Note History::. 'hstatus STATUS' Change the window's hardstatus line. *Note Hardstatus::. 'idle [TIMEOUT [CMD ARGS]]' Define a screen saver command. *Note Screen Saver::. 'ignorecase [on|off]' Ignore character case in searches. *Note Searching::. 'info' Display window settings. *Note Info::. 'ins_reg [KEY]' Removed, use 'paste' instead. *Note Registers::. 'kill' Destroy the current window. *Note Kill::. 'lastmsg' Redisplay the last message. *Note Last Message::. 'layout new [TITLE]' Create a layout. *Note Layout::. 'layout remove [N|TITLE]' Delete a layout. *Note Layout::. 'layout next' Select the next layout. *Note Layout::. 'layout prev' Select the previous layout. *Note Layout::. 'layout select [N|TITLE]' Jump to a layout. *Note Layout::. 'layout show' List the available layouts. *Note Layout::. 'layout title [TITLE]' Show or set the title of a layout. *Note Layout::. 'layout number [N]' Show or set the number of a layout. *Note Layout::. 'layout attach [TITLE|:last]' Show or set which layout to reattach to. *Note Layout::. 'layout save [N|TITLE]' Remember the organization of a layout. *Note Layout::. 'layout autosave [ON|OFF]' Show or set the status of layout saving. *Note Layout::. 'layout dump [filename]' Save the layout arrangement to a file. *Note Layout::. 'license' Display licensing information. *Note Startup::. 'lockscreen' Lock the controlling terminal. *Note Lock::. 'log [STATE]' Log all output in the current window. *Note Log::. 'logfile FILENAME' Place where to collect logfiles. *Note Log::. 'login [STATE]' Log the window in '/etc/utmp'. *Note Login::. 'logtstamp [STATE]' Configure logfile time-stamps. *Note Log::. 'mapdefault' Use only the default mapping table for the next keystroke. *Note Bindkey Control::. 'mapnotnext' Don't try to do keymapping on the next keystroke. *Note Bindkey Control::. 'maptimeout N' Set the inter-character timeout used for keymapping. *Note Bindkey Control::. 'markkeys STRING' Rebind keys in copy mode. *Note Copy Mode Keys::. 'maxwin N' Set the maximum window number. *Note Maxwin::. 'meta' Insert the command character. *Note Command Character::. 'monitor [STATE]' Monitor activity in window. *Note Monitor::. 'mousetrack [ON|OFF]' Enable selecting split regions with mouse clicks. *Note Mousetrack::. 'msgminwait SEC' Set minimum message wait. *Note Message Wait::. 'msgwait SEC' Set default message wait. *Note Message Wait::. 'multiuser STATE' Go into single or multi user mode. *Note Multiuser Session::. 'nethack STATE' Use 'nethack'-like error messages. *Note Nethack::. 'next' Switch to the next window. *Note Selecting::. 'nonblock [STATE|NUMSECS]' Disable flow control to the current display. *Note Nonblock::.|NUMSECS] 'number [N]' Change/display the current window's number. *Note Number::. 'obuflimit [LIMIT]' Select output buffer limit. *Note Obuflimit::. 'only' Kill all other regions. *Note Regions::. 'other' Switch to the window you were in last. *Note Selecting::. 'partial STATE' Set window to partial refresh. *Note Redisplay::. 'password [CRYPTED_PW]' Set reattach password. *Note Detach::. 'paste [SRC_REGS [DEST_REG]]' Paste contents of paste buffer or registers somewhere. *Note Paste::. 'pastefont [STATE]' Include font information in the paste buffer. *Note Paste::. 'pow_break' Close and Reopen the window's terminal. *Note Break::. 'pow_detach' Detach and hang up. *Note Power Detach::. 'pow_detach_msg [MESSAGE]' Set message displayed on 'pow_detach'. *Note Power Detach::. 'prev' Switch to the previous window. *Note Selecting::. 'printcmd [CMD]' Set a command for VT100 printer port emulation. *Note Printcmd::. 'process [KEY]' Treat a register as input to 'screen'. *Note Registers::. 'quit' Kill all windows and exit. *Note Quit::. 'readbuf [-e ENCODING] [FILENAME]' Read the paste buffer from the screen-exchange file. *Note Screen Exchange::. 'readreg [-e ENCODING] [REG [FILE]]' Load a register from paste buffer or file. *Note Registers::. 'redisplay' Redisplay the current window. *Note Redisplay::. 'register [-e ENCODING] KEY STRING' Store a string to a register. *Note Registers::. 'remove' Kill current region. *Note Regions::. 'removebuf' Delete the screen-exchange file. *Note Screen Exchange::. 'rendition bell | monitor | silence | so ATTR [COLOR]' Change text attributes in caption for flagged windows. *Note Rendition::. 'reset' Reset the terminal settings for the window. *Note Reset::. 'resize [(+/-)lines]' Grow or shrink a region. *Note Resize::. 'screen [OPTS] [N] [CMD [ARGS] | //group]' Create a new window. *Note Screen Command::. 'scrollback NUM' Set size of scrollback buffer. *Note Scrollback::. 'select [N|-|.]' Switch to a specified window. *Note Selecting::. 'sessionname [NAME]' Name this session. *Note Session Name::. 'setenv [VAR [STRING]]' Set an environment variable for new windows. *Note Setenv::. 'setsid STATE' Controll process group creation for windows. *Note Setsid::. 'shell COMMAND' Set the default program for new windows. *Note Shell::. 'shelltitle TITLE' Set the default name for new windows. *Note Shell::. 'silence [STATE|SECONDS]' Monitor a window for inactivity. *Note Monitor::. 'silencewait SECONDS' Default timeout to trigger an inactivity notify. *Note Monitor::. 'sleep NUM' Pause during startup. *Note Startup::. 'slowpaste MSEC' Slow down pasting in windows. *Note Paste::. 'source FILE' Run commands from a file. *Note Source::. 'sorendition [ATTR [COLOR]]' Deprecated. Use 'rendition so' instead. *Note Rendition::. 'split' Split region into two parts. *Note Regions::. 'startup_message STATE' Display copyright notice on startup. *Note Startup::. 'stuff [STRING]' Stuff a string in the input buffer of a window. *Note Paste::. 'su [USERNAME [PASSWORD [PASSWORD2]]]' Identify a user. *Note Multiuser Session::. 'suspend' Put session in background. *Note Suspend::. 'term TERM' Set '$TERM' for new windows. *Note Term::. 'termcap TERM TERMINAL-TWEAKS [WINDOW-TWEAKS]' Tweak termcap entries for best performance. *Note Termcap Syntax::. 'terminfo TERM TERMINAL-TWEAKS [WINDOW-TWEAKS]' Ditto, for terminfo systems. *Note Termcap Syntax::. 'termcapinfo TERM TERMINAL-TWEAKS [WINDOW-TWEAKS]' Ditto, for both systems. *Note Termcap Syntax::. 'time [STRING]' Display time and load average. *Note Time::. 'title [WINDOWTITLE]' Set the name of the current window. *Note Title Command::. 'umask [USERS]+/-BITS ...' Synonym to 'aclumask'. *Note Umask::. 'unbindall' Unset all keybindings. *Note Bind::. 'unsetenv VAR' Unset environment variable for new windows. *Note Setenv::. 'utf8 [STATE [DSTATE]]' Select character encoding of the current window. *Note Character Processing::. 'vbell [STATE]' Use visual bell. *Note Bell::. 'vbell_msg [MESSAGE]' Set vbell message. *Note Bell::. 'vbellwait SEC' Set delay for vbell message. *Note Bell::. 'version' Display 'screen' version. *Note Version::. 'wall MESSAGE' Write a message to all displays. *Note Multiuser Session::. 'width [COLS [LINES]]' Set the width of the window. *Note Window Size::. 'windowlist [[-b] [-m] [-g]] | string [STRING] | title [TITLE]' Present a list of all windows for selection. *Note Windowlist::. 'windows' List active windows. *Note Windows::. 'wrap [ on | off ]' Control line-wrap behavior. *Note Wrap::. 'writebuf [-e ENCODING] [FILENAME]' Write paste buffer to screen-exchange file. *Note Screen Exchange::. 'writelock ON|OFF|AUTO' Grant exclusive write permission. *Note Multiuser Session::. 'xoff' Send an XOFF character. *Note XON/XOFF::. 'xon' Send an XON character. *Note XON/XOFF::. 'zmodem [off|auto|catch|pass]' Define how screen treats zmodem requests. *Note Zmodem::. 'zombie [KEYS [onerror] ]' Keep dead windows. *Note Zombie::. 6 New Window ************ This section describes the commands for creating a new window for running programs. When a new window is created, the first available number is assigned to it. The number of windows is limited at compile-time by the MAXWIN configuration parameter (which defaults to 40). 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. *Note Window Groups::. Screen has built in some functionality of 'cu' and 'telnet'. *Note 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 '$SHELL'. If the command begins with a '-' character, the shell will be started as a login-shell. Typical shells do only minimal initialization when not started as a login-shell. E.g. Bash will not read your '~/.bashrc' unless it is a login-shell. 'defshell' is currently a synonym to the 'shell' .screenrc command. -- Command: shelltitle title (none) Set the title for all shells created during startup or by the C-a C-c command. *Note Naming Windows::, for details about what titles are. 6.5 Term ======== -- Command: term term (none) In each window 'screen' opens, it sets the '$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 (*note Screen Command::). The first parameter to the 'screen' command defines which type of window is created. The different window types are all special cases of the normal type. They have been added in order to allow 'screen' to be used efficiently as a console with 100 or more windows. * The normal window contains a shell (default, if no parameter is given) or any other system command that could be executed from a shell. (e.g. 'slogin', etc...). * If a tty (character special device) name (e.g. '/dev/ttya') is specified as the first parameter, then the window is directly connected to this device. This window type is similar to 'screen cu -l /dev/ttya'. Read and write access is required on the device node, an exclusive open is attempted on the node to mark the connection line as busy. An optional parameter is allowed consisting of a comma separated list of flags in the notation used by 'stty(1)': '' Usually 300, 1200, 9600 or 19200. This affects transmission as well as receive speed. 'cs8 or cs7' Specify the transmission of eight (or seven) bits per byte. 'ixon or -ixon' Enables (or disables) software flow-control (CTRL-S/CTRL-Q) for sending data. 'ixoff or -ixoff' Enables (or disables) software flow-control for receiving data. 'istrip or -istrip' Clear (or keep) the eight bit in each received byte. You may want to specify as many of these options as applicable. Unspecified options cause the terminal driver to make up the parameter values of the connection. These values are system-dependent and may be in defaults or values saved from a previous connection. For tty windows, the 'info' command shows some of the modem control lines in the status line. These may include 'RTS', 'CTS', 'DTR', 'CD' and more. This depends rather on on the available 'ioctl()''s and system header files than on the physical capabilities of the serial board. The name of a logical low (inactive) signal is preceded by an exclamation mark ('!'), otherwise the signal is logical high (active). Unsupported but shown signals are usually shown low. When the 'CLOCAL' status bit is true, the whole set of modem signals is placed inside curly braces ('{' and '}'). When the 'CRTSCTS' or 'TIOCSOFTCAR' bit is true, the signals 'CTS' or 'CD' are shown in parenthesis, respectively. For tty windows, the command 'break' causes the Data transmission line (TxD) to go low for a specified period of time. This is expected to be interpreted as break signal on the other side. No data is sent and no modem control line is changed when a 'break' is issued. * If the first parameter is '//telnet', the second parameter is expected to be a host name, and an optional third parameter may specify a TCP port number (default decimal 23). Screen will connect to a server listening on the remote host and use the telnet protocol to communicate with that server. For telnet windows, the command 'info' shows details about the connection in square brackets ('[' and ']') at the end of the status line. 'b' BINARY. The connection is in binary mode. 'e' ECHO. Local echo is disabled. 'c' SGA. The connection is in 'character mode' (default: 'line mode'). 't' TTYPE. The terminal type has been requested by the remote host. Screen sends the name 'screen' unless instructed otherwise (see also the command 'term'). 'w' NAWS. The remote site is notified about window size changes. 'f' LFLOW. The remote host will send flow control information. (Ignored at the moment.) Additional flags for debugging are 'x', 't' and 'n' (XDISPLOC, TSPEED and NEWENV). For telnet windows, the command 'break' sends the telnet code 'IAC BREAK' (decimal 243) to the remote host. 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'. *Note 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. *Note 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 (*note New Window::). 7.1 Moving Back and Forth ========================= -- Command: next ('C-a ', '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- 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 ') 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 ']]' (*note 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 (*note 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. 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 (*note 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. 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'. (*note 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. 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 ') 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. *Note 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 (*note 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. *Note Virtual Terminal::, for commands to control the terminal emulation itself. 10.1 Naming Windows (Titles) ============================ You can customize each window's name in the window display (viewed with the 'windows' command (*note 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 (*note Shell::). You can specify the name you want for a window with the '-t' option to the 'screen' command when the window is created (*note Screen Command::). To change the name after the window has been created you can use the title-string escape-sequence (' k NAME \') 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. 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 ( k \) 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='^[[0000m^[k^[\% ' The escape-sequence '^[[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 (*note 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 (*note Command Character::) or rebind 'kill' to another key sequence, such as 'C-a K' (*note 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 (*note 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' (*note 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, *note 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 (*note 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 '$' (*note 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 '@' (*note 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 (*note 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_ESC\'. As a convenience for xterm users the sequence 'ESC]0..2;^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', *note 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 *note 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 ¦ U+00A6 'B', 'B' 166 ¦ U+00A6 'p', 'a' 167 § U+00A7 'S', 'E' 167 § U+00A7 '"', '"' 168 ¨ U+00A8 ''', ':' 168 ¨ 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 ´ 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 ¸ U+00B8 ''', ',' 184 ¸ 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 ¼ U+00BC '1', '2' 189 ½ U+00BD '3', '4' 190 ¾ 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'. *Note 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 (*note 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 (*note 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 (*note 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. *Note 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 *note 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. 12.1 Copying ============ -- Command: copy ('C-a [', 'C-a C-[', 'C-a ') 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. 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. *Note 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. *Note 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. *Note 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 string can be specified via the '-e' option. 12.4 Screen Exchange ==================== -- Command: bufferfile [EXCHANGE-FILE] (none) Change the filename used for reading and writing with the paste buffer. If the EXCHANGE-FILE parameter is omitted, 'screen' reverts to the default of '/tmp/screen-exchange'. The following example will paste the system's password file into the screen window (using the paste buffer, where a copy remains): C-a : bufferfile /etc/passwd C-a < C-a ] C-a : bufferfile -- Command: readbuf [-e ENCODING] [FILENAME] ('C-a <') Reads the contents of the specified file into the paste buffer. You can tell screen the encoding of the file via the '-e' option. If no file is specified, the screen-exchange filename is used. -- Command: removebuf ('C-a =') Unlinks the screen-exchange file. -- Command: writebuf [-e ENCODING] [FILENAME] ('C-a >') Writes the contents of the paste buffer to the specified file, or the public accessible screen-exchange file if no filename is given. This is thought of as a primitive means of communication between 'screen' users on the same host. If an encoding is specified the paste buffer is recoded on the fly to match the encoding. See also 'C-a ' (*note Copy::). 12.5 History ============ -- Command: history ('C-a {', 'C-a }') Usually users work with a shell that allows easy access to previous commands. For example, 'csh' has the command '!!' to repeat the last command executed. 'screen' provides a primitive way of recalling "the command that started ...": You just type the first letter of that command, then hit 'C-a {' and 'screen' tries to find a previous line that matches with the prompt character to the left of the cursor. This line is pasted into this window's input queue. Thus you have a crude command history (made up by the visible window and its scrollback buffer). 13 Subprocess Execution *********************** Control Input or Output of a window by another filter process. Use with care! 13.1 Exec ========= -- Command: exec [[FDPAT] NEWCOMMAND [ARGS ... ]] (none) Run a unix subprocess (specified by an executable path NEWCOMMAND and its optional arguments) in the current window. The flow of data between newcommands stdin/stdout/stderr, the process originally started (let us call it "application-process") and screen itself (window) is controlled by the file descriptor pattern FDPAT. This pattern is basically a three character sequence representing stdin, stdout and stderr of newcommand. A dot ('.') connects the file descriptor to screen. An exclamation mark ('!') causes the file descriptor to be connected to the application-process. A colon (':') combines both. User input will go to newcommand unless newcommand receives the application-process' output (FDPATs first character is '!' or ':') or a pipe symbol ('|') is added to the end of FDPAT. Invoking 'exec' without arguments shows name and arguments of the currently running subprocess in this window. Only one subprocess can be running per window. When a subprocess is running the 'kill' command will affect it instead of the windows process. Only one subprocess a time can be running in each window. Refer to the postscript file 'doc/fdpat.ps' for a confusing illustration of all 21 possible combinations. Each drawing shows the digits 2, 1, 0 representing the three file descriptors of newcommand. The box marked 'W' is usual pty that has the application-process on its slave side. The box marked 'P' is the secondary pty that now has screen at its master side. 13.2 Using Exec =============== Abbreviations: * Whitespace between the word 'exec' and FDPAT and the command name can be omitted. * Trailing dots and a FDPAT consisting only of dots can be omitted. * A simple '|' is synonymous for the '!..|' pattern. * The word 'exec' can be omitted when the '|' abbreviation is used. * The word 'exec' can always be replaced by leading '!'. Examples: '!/bin/sh' 'exec /bin/sh' 'exec ... /bin/sh' All of the above are equivalent. Creates another shell in the same window, while the original shell is still running. Output of both shells is displayed and user input is sent to the new '/bin/sh'. '!!stty 19200' 'exec!stty 19200' 'exec !.. stty 19200' All of the above are equivalent. Set the speed of the window's tty. If your stty command operates on stdout, then add another '!'. This is a useful command, when a screen window is directly connected to a serial line that needs to be configured. '|less' 'exec !..| less' Both are equivalent. This adds a pager to the window output. The special character '|' is needed to give the user control over the pager although it gets its input from the window's process. This works, because 'less' listens on stderr (a behavior that 'screen' would not expect without the '|') when its stdin is not a tty. 'Less' versions newer than 177 fail miserably here; good old 'pg' still works. '!:sed -n s/.*Error.*/\007/p' Sends window output to both, the user and the sed command. The sed inserts an additional bell character (oct. 007) to the window output seen by screen. This will cause 'Bell in window x' messages, whenever the string 'Error' appears in the window. 14 Key Binding ************** You may disagree with some of the default bindings (I know I do). The 'bind' command allows you to redefine them to suit your preferences. 14.1 The 'bind' command ======================= -- Command: bind [-c class] key [command [args]] (none) Bind a command to a key. The KEY argument is either a single character, a two-character sequence of the form '^x' (meaning 'C-x'), a backslash followed by an octal number (specifying the ASCII code of the character), or a backslash followed by a second character, such as '\^' or '\\'. The argument can also be quoted, if you like. If no further argument is given, any previously established binding for this key is removed. The COMMAND argument can be any command (*note Command Index::). If a command class is specified via the '-c' option, the key is bound for the specified class. Use the 'command' command to activate a class. Command classes can be used to create multiple command keys or multi-character bindings. By default, most suitable commands are bound to one or more keys (*note Default Key Bindings::); for instance, the command to create a new window is bound to 'C-c' and 'c'. The 'bind' command can be used to redefine the key bindings and to define new bindings. -- Command: unbindall (none) Unbind all the bindings. This can be useful when screen is used solely for its detaching abilities, such as when letting a console application run as a daemon. If, for some reason, it is necessary to bind commands after this, use 'screen -X'. 14.2 Examples of the 'bind' command =================================== Some examples: bind ' ' windows bind ^f screen telnet foobar bind \033 screen -ln -t root -h 1000 9 su would bind the space key to the command that displays a list of windows (so that the command usually invoked by 'C-a C-w' would also be available as 'C-a space'), bind 'C-f' to the command "create a window with a TELNET connection to foobar", and bind to the command that creates an non-login window with title 'root' in slot #9, with a superuser shell and a scrollback buffer of 1000 lines. bind -c demo1 0 select 10 bind -c demo1 1 select 11 bind -c demo1 2 select 12 bindkey "^B" command -c demo1 makes 'C-b 0' select window 10, 'C-b 1' window 11, etc. bind -c demo2 0 select 10 bind -c demo2 1 select 11 bind -c demo2 2 select 12 bind - command -c demo2 makes 'C-a - 0' select window 10, 'C-a - 1' window 11, etc. 14.3 Command Character ====================== -- Command: escape xy (none) Set the command character to X and the character generating a literal command character (by triggering the 'meta' command) to Y (similar to the '-e' option). Each argument is either a single character, a two-character sequence of the form '^x' (meaning 'C-x'), a backslash followed by an octal number (specifying the ASCII code of the character), or a backslash followed by a second character, such as '\^' or '\\'. The default is '^Aa', but '``' is recommended by one of the authors. -- Command: defescape xy (none) Set the default command characters. This is equivalent to the command 'escape' except that it is useful for multiuser sessions only. In a multiuser session 'escape' changes the command character of the calling user, where 'defescape' changes the default command characters for users that will be added later. -- Command: meta ('C-a a') Send the command character ('C-a') to the process in the current window. The keystroke for this command is the second parameter to the '-e' command line switch (*note Invoking Screen::), or the 'escape' .screenrc directive. -- Command: command [-c CLASS] (none) This command has the same effect as typing the screen escape character ('C-a'). It is probably only useful for key bindings. If the '-c' option is given, select the specified command class. *Note Bind::, *Note Bindkey::. 14.4 Help ========= -- Command: help ('C-a ?') Displays a help screen showing you all the key bindings. The first pages list all the internal commands followed by their bindings. Subsequent pages will display the custom commands, one command per key. Press space when you're done reading each page, or return to exit early. All other characters are ignored. If the '-c' option is given, display all bound commands for the specified command class. *Note Default Key Bindings::. 14.5 Bindkey ============ -- Command: bindkey [OPTS] [STRING [CMD ARGS]] (none) This command manages screen's input translation tables. Every entry in one of the tables tells screen how to react if a certain sequence of characters is encountered. There are three tables: one that should contain actions programmed by the user, one for the default actions used for terminal emulation and one for screen's copy mode to do cursor movement. See *note Input Translation:: for a list of default key bindings. If the '-d' option is given, bindkey modifies the default table, '-m' changes the copy mode table and with neither option the user table is selected. The argument 'string' is the sequence of characters to which an action is bound. This can either be a fixed string or a termcap keyboard capability name (selectable with the '-k' option). Some keys on a VT100 terminal can send a different string if application mode is turned on (e.g. the cursor keys). Such keys have two entries in the translation table. You can select the application mode entry by specifying the '-a' option. The '-t' option tells screen not to do inter-character timing. One cannot turn off the timing if a termcap capability is used. 'cmd' can be any of screen's commands with an arbitrary number of 'args'. If 'cmd' is omitted the key-binding is removed from the table. 14.6 Bindkey Examples ===================== Here are some examples of keyboard bindings: bindkey -d Show all of the default key bindings. The application mode entries are marked with [A]. bindkey -k k1 select 1 Make the "F1" key switch to window one. bindkey -t foo stuff barfoo Make 'foo' an abbreviation of the word 'barfoo'. Timeout is disabled so that users can type slowly. bindkey "\024" mapdefault This key-binding makes 'C-t' an escape character for key-bindings. If you did the above 'stuff barfoo' binding, you can enter the word 'foo' by typing 'C-t foo'. If you want to insert a 'C-t' you have to press the key twice (i.e., escape the escape binding). bindkey -k F1 command Make the F11 (not F1!) key an alternative screen escape (besides 'C-a'). 14.7 Bindkey Control ==================== -- Command: mapdefault (none) Tell screen that the next input character should only be looked up in the default bindkey table. -- Command: mapnotnext (none) Like mapdefault, but don't even look in the default bindkey table. -- Command: maptimeout n (none) Set the inter-character timer for input sequence detection to a timeout of N ms. The default timeout is 300ms. Maptimeout with no arguments shows the current setting. 15 Flow Control *************** 'screen' can trap flow control characters or pass them to the program, as you see fit. This is useful when your terminal wants to use XON/XOFF flow control and you are running a program which wants to use ^S/^Q for other purposes (i.e. 'emacs'). 15.1 About 'screen' flow control settings ========================================= Each window has a flow-control setting that determines how screen deals with the XON and XOFF characters (and perhaps the interrupt character). When flow-control is turned off, screen ignores the XON and XOFF characters, which allows the user to send them to the current program by simply typing them (useful for the 'emacs' editor, for instance). The trade-off is that it will take longer for output from a "normal" program to pause in response to an XOFF. With flow-control turned on, XON and XOFF characters are used to immediately pause the output of the current window. You can still send these characters to the current program, but you must use the appropriate two-character screen commands (typically 'C-a q' (xon) and 'C-a s' (xoff)). The xon/xoff commands are also useful for typing C-s and C-q past a terminal that intercepts these characters. Each window has an initial flow-control value set with either the '-f' option or the 'defflow' command. By default the windows are set to automatic flow-switching. It can then be toggled between the three states 'fixed on', 'fixed off' and 'automatic' interactively with the 'flow' command bound to 'C-a f'. The automatic flow-switching mode deals with flow control using the TIOCPKT mode (like 'rlogin' does). If the tty driver does not support TIOCPKT, screen tries to determine the right mode based on the current setting of the application keypad -- when it is enabled, flow-control is turned off and visa versa. Of course, you can still manipulate flow-control manually when needed. If you're running with flow-control enabled and find that pressing the interrupt key (usually C-c) does not interrupt the display until another 6-8 lines have scrolled by, try running screen with the 'interrupt' option (add the 'interrupt' flag to the 'flow' command in your .screenrc, or use the '-i' command-line option). This causes the output that 'screen' has accumulated from the interrupted program to be flushed. One disadvantage is that the virtual terminal's memory contains the non-flushed version of the output, which in rare cases can cause minor inaccuracies in the output. For example, if you switch screens and return, or update the screen with 'C-a l' you would see the version of the output you would have gotten without 'interrupt' being on. Also, you might need to turn off flow-control (or use auto-flow mode to turn it off automatically) when running a program that expects you to type the interrupt character as input, as the 'interrupt' parameter only takes effect when flow-control is enabled. If your program's output is interrupted by mistake, a simple refresh of the screen with 'C-a l' will restore it. Give each mode a try, and use whichever mode you find more comfortable. 15.2 Flow ========= -- Command: defflow fstate [interrupt] (none) Same as the 'flow' command except that the default setting for new windows is changed. Initial setting is 'auto'. Specifying 'flow auto interrupt' has the same effect as the command-line options '-fa' and '-i'. Note that if 'interrupt' is enabled, all existing displays are changed immediately to forward interrupt signals. -- Command: flow [fstate] ('C-a f', 'C-a C-f') Sets the flow-control mode for this window to FSTATE, which can be 'on', 'off' or 'auto'. Without parameters it cycles the current window's flow-control setting. Default is set by 'defflow'. 15.3 XON and XOFF ================= -- Command: xon ('C-a q', 'C-a C-q') Send a ^Q (ASCII XON) to the program in the current window. Redundant if flow control is set to 'off' or 'auto'. -- Command: xoff ('C-a s', 'C-a C-s') Send a ^S (ASCII XOFF) to the program in the current window. 16 Termcap ********** 'Screen' demands the most out of your terminal so that it can perform its VT100 emulation most efficiently. These functions provide means for tweaking the termcap entries for both your physical terminal and the one simulated by 'screen'. 16.1 Choosing the termcap entry for a window ============================================ Usually 'screen' tries to emulate as much of the VT100/ANSI standard as possible. But if your terminal lacks certain capabilities the emulation may not be complete. In these cases 'screen' has to tell the applications that some of the features are missing. This is no problem on machines using termcap, because 'screen' can use the '$TERMCAP' variable to customize the standard screen termcap. But if you do a rlogin on another machine or your machine supports only terminfo this method fails. Because of this 'screen' offers a way to deal with these cases. Here is how it works: When 'screen' tries to figure out a terminal name for itself, it first looks for an entry named 'screen.TERM', where TERM is the contents of your '$TERM' variable. If no such entry exists, 'screen' tries 'screen' (or 'screen-w', if the terminal is wide (132 cols or more)). If even this entry cannot be found, 'vt100' is used as a substitute. The idea is that if you have a terminal which doesn't support an important feature (e.g. delete char or clear to EOS) you can build a new termcap/terminfo entry for 'screen' (named 'screen.DUMBTERM') in which this capability has been disabled. If this entry is installed on your machines you are able to do a rlogin and still keep the correct termcap/terminfo entry. The terminal name is put in the '$TERM' variable of all new windows. 'screen' also sets the '$TERMCAP' variable reflecting the capabilities of the virtual terminal emulated. Furthermore, the variable '$WINDOW' is set to the window number of each window. The actual set of capabilities supported by the virtual terminal depends on the capabilities supported by the physical terminal. If, for instance, the physical terminal does not support underscore mode, 'screen' does not put the 'us' and 'ue' capabilities into the window's '$TERMCAP' variable, accordingly. However, a minimum number of capabilities must be supported by a terminal in order to run 'screen'; namely scrolling, clear screen, and direct cursor addressing (in addition, 'screen' does not run on hardcopy terminals or on terminals that over-strike). Also, you can customize the '$TERMCAP' value used by 'screen' by using the 'termcap' command, or by defining the variable '$SCREENCAP' prior to startup. When the latter defined, its value will be copied verbatim into each window's '$TERMCAP' variable. This can either be the full terminal definition, or a filename where the terminal 'screen' (and/or 'screen-w') is defined. Note that 'screen' honors the 'terminfo' command if the system uses the terminfo database rather than termcap. On such machines the '$TERMCAP' variable has no effect and you must use the 'dumptermcap' command (*note Dump Termcap::) and the 'tic' program to generate terminfo entries for 'screen' windows. When the boolean 'G0' capability is present in the termcap entry for the terminal on which 'screen' has been called, the terminal emulation of 'screen' supports multiple character sets. This allows an application to make use of, for instance, the VT100 graphics character set or national character sets. The following control functions from ISO 2022 are supported: 'lock shift G0' ('SI'), 'lock shift G1' ('SO'), 'lock shift G2', 'lock shift G3', 'single shift G2', and 'single shift G3'. When a virtual terminal is created or reset, the ASCII character set is designated as 'G0' through 'G3'. When the 'G0' capability is present, screen evaluates the capabilities 'S0', 'E0', and 'C0' if present. 'S0' is the sequence the terminal uses to enable and start the graphics character set rather than 'SI'. 'E0' is the corresponding replacement for 'SO'. 'C0' gives a character by character translation string that is used during semi-graphics mode. This string is built like the 'acsc' terminfo capability. When the 'po' and 'pf' capabilities are present in the terminal's termcap entry, applications running in a 'screen' window can send output to the printer port of the terminal. This allows a user to have an application in one window sending output to a printer connected to the terminal, while all other windows are still active (the printer port is enabled and disabled again for each chunk of output). As a side-effect, programs running in different windows can send output to the printer simultaneously. Data sent to the printer is not displayed in the window. The 'info' command displays a line starting with 'PRIN' while the printer is active. Some capabilities are only put into the '$TERMCAP' variable of the virtual terminal if they can be efficiently implemented by the physical terminal. For instance, 'dl' (delete line) is only put into the '$TERMCAP' variable if the terminal supports either delete line itself or scrolling regions. Note that this may provoke confusion, when the session is reattached on a different terminal, as the value of '$TERMCAP' cannot be modified by parent processes. You can force 'screen' to include all capabilities in '$TERMCAP' with the '-a' command-line option (*note Invoking Screen::). The "alternate screen" capability is not enabled by default. Set the 'altscreen' '.screenrc' command to enable it. 16.2 Write out the window's termcap entry ========================================= -- Command: dumptermcap ('C-a .') Write the termcap entry for the virtual terminal optimized for the currently active window to the file '.termcap' in the user's '$HOME/.screen' directory (or wherever 'screen' stores its sockets. *note Files::). This termcap entry is identical to the value of the environment variable '$TERMCAP' that is set up by 'screen' for each window. For terminfo based systems you will need to run a converter like 'captoinfo' and then compile the entry with 'tic'. 16.3 The 'termcap' command ========================== -- Command: termcap term terminal-tweaks [window-tweaks] -- Command: terminfo term terminal-tweaks [window-tweaks] -- Command: termcapinfo term terminal-tweaks [window-tweaks] (none) Use this command to modify your terminal's termcap entry without going through all the hassles involved in creating a custom termcap entry. Plus, you can optionally customize the termcap generated for the windows. You have to place these commands in one of the screenrc startup files, as they are meaningless once the terminal emulator is booted. If your system uses the terminfo database rather than termcap, 'screen' will understand the 'terminfo' command, which has the same effects as the 'termcap' command. Two separate commands are provided, as there are subtle syntactic differences, e.g. when parameter interpolation (using '%') is required. Note that the termcap names of the capabilities should also be used with the 'terminfo' command. In many cases, where the arguments are valid in both terminfo and termcap syntax, you can use the command 'termcapinfo', which is just a shorthand for a pair of 'termcap' and 'terminfo' commands with identical arguments. The first argument specifies which terminal(s) should be affected by this definition. You can specify multiple terminal names by separating them with '|'s. Use '*' to match all terminals and 'vt*' to match all terminals that begin with 'vt'. Each TWEAK argument contains one or more termcap defines (separated by ':'s) to be inserted at the start of the appropriate termcap entry, enhancing it or overriding existing values. The first tweak modifies your terminal's termcap, and contains definitions that your terminal uses to perform certain functions. Specify a null string to leave this unchanged (e.g. ""). The second (optional) tweak modifies all the window termcaps, and should contain definitions that screen understands (*note Virtual Terminal::). 16.4 Termcap Examples ===================== Some examples: termcap xterm* xn:hs@ Informs 'screen' that all terminals that begin with 'xterm' have firm auto-margins that allow the last position on the screen to be updated (xn), but they don't really have a status line (no 'hs' - append '@' to turn entries off). Note that we assume 'xn' for all terminal names that start with 'vt', but only if you don't specify a termcap command for that terminal. termcap vt* xn termcap vt102|vt220 Z0=\E[?3h:Z1=\E[?3l Specifies the firm-margined 'xn' capability for all terminals that begin with 'vt', and the second line will also add the escape-sequences to switch into (Z0) and back out of (Z1) 132-character-per-line mode if this is a VT102 or VT220. (You must specify Z0 and Z1 in your termcap to use the width-changing commands.) termcap vt100 "" l0=PF1:l1=PF2:l2=PF3:l3=PF4 This leaves your vt100 termcap alone and adds the function key labels to each window's termcap entry. termcap h19|z19 am@:im=\E@:ei=\EO dc=\E[P Takes a h19 or z19 termcap and turns off auto-margins (am@) and enables the insert mode (im) and end-insert (ei) capabilities (the '@' in the 'im' string is after the '=', so it is part of the string). Having the 'im' and 'ei' definitions put into your terminal's termcap will cause screen to automatically advertise the character-insert capability in each window's termcap. Each window will also get the delete-character capability (dc) added to its termcap, which screen will translate into a line-update for the terminal (we're pretending it doesn't support character deletion). If you would like to fully specify each window's termcap entry, you should instead set the '$SCREENCAP' variable prior to running 'screen'. *Note Virtual Terminal::, for the details of the 'screen' terminal emulation. *Note Termcap::, for more information on termcap definitions. 16.5 Special Terminal Capabilities ================================== The following table describes all terminal capabilities that are recognized by 'screen' and are not in the termcap manual (*note Termcap::). You can place these capabilities in your termcap entries (in '/etc/termcap') or use them with the commands 'termcap', 'terminfo' and 'termcapinfo' in your 'screenrc' files. It is often not possible to place these capabilities in the terminfo database. 'LP' (bool) Terminal has VT100 style margins ('magic margins'). Note that this capability is obsolete -- 'screen' now uses the standard 'xn' instead. 'Z0' (str) Change width to 132 columns. 'Z1' (str) Change width to 80 columns. 'WS' (str) Resize display. This capability has the desired width and height as arguments. SunView(tm) example: '\E[8;%d;%dt'. 'NF' (bool) Terminal doesn't need flow control. Send ^S and ^Q direct to the application. Same as 'flow off'. The opposite of this capability is 'nx'. 'G0' (bool) Terminal can deal with ISO 2022 font selection sequences. 'S0' (str) Switch charset 'G0' to the specified charset. Default is '\E(%.'. 'E0' (str) Switch charset 'G0' back to standard charset. Default is '\E(B'. 'C0' (str) Use the string as a conversion table for font 0. See the 'ac' capability for more details. 'CS' (str) Switch cursor-keys to application mode. 'CE' (str) Switch cursor-keys to cursor mode. 'AN' (bool) Enable autonuke for displays of this terminal type. (*note Autonuke::). 'OL' (num) Set the output buffer limit. See the 'obuflimit' command (*note Obuflimit::) for more details. 'KJ' (str) Set the encoding of the terminal. See the 'encoding' command (*note Character Processing::) for valid encodings. 'AF' (str) Change character foreground color in an ANSI conform way. This capability will almost always be set to '\E[3%dm' ('\E[3%p1%dm' on terminfo machines). 'AB' (str) Same as 'AF', but change background color. 'AX' (bool) Does understand ANSI set default fg/bg color ('\E[39m / \E[49m'). 'XC' (str) Describe a translation of characters to strings depending on the current font. (*note Character Translation::). 'XT' (bool) Terminal understands special xterm sequences (OSC, mouse tracking). 'C8' (bool) Terminal needs bold to display high-intensity colors (e.g. Eterm). 'TF' (bool) Add missing capabilities to the termcap/info entry. (Set by default). 16.6 Autonuke ============= -- Command: autonuke STATE (none) Sets whether a clear screen sequence should nuke all the output that has not been written to the terminal. *Note Obuflimit::. This property is set per display, not per window. -- Command: defautonuke STATE (none) Same as the 'autonuke' command except that the default setting for new displays is also changed. Initial setting is 'off'. Note that you can use the special 'AN' terminal capability if you want to have a terminal type dependent setting. 16.7 Obuflimit ============== -- Command: obuflimit [LIMIT] (none) If the output buffer contains more bytes than the specified limit, no more data will be read from the windows. The default value is 256. If you have a fast display (like 'xterm'), you can set it to some higher value. If no argument is specified, the current setting is displayed. This property is set per display, not per window. -- Command: defobuflimit LIMIT (none) Same as the 'obuflimit' command except that the default setting for new displays is also changed. Initial setting is 256 bytes. Note that you can use the special 'OL' terminal capability if you want to have a terminal type dependent limit. 16.8 Character Translation ========================== 'Screen' has a powerful mechanism to translate characters to arbitrary strings depending on the current font and terminal type. Use this feature if you want to work with a common standard character set (say ISO8851-latin1) even on terminals that scatter the more unusual characters over several national language font pages. Syntax: XC={,,} :=