screen

SCREEN(1)                                                            SCREEN(1)

NAME
       screen – screen manager with VT100/ANSI terminal emulation

SYNOPSIS
       screen [ -options ] [ cmd [ args ] ]
       screen -r [[pid.]tty[.host]]
       screen -r sessionowner/[[pid.]tty[.host]]

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

       When screen is called, it creates a single window with a shell in it (or the specified command) and then gets out of your way so that you can use the pro-
       gram  as you normally would.  Then, at any time, you can create new (full-screen) windows with other programs in them (including more shells), kill exist-
       ing windows, view a list of windows, turn output logging on and off, copy-and-paste text between windows, view the scrollback history, switch between win-
       dows  in whatever manner you wish, etc. All windows run their programs completely independent of each other. Programs continue to run when their window is
       currently not visible and even when the whole screen session is detached from the user’s terminal.  When a program terminates, screen (per default)  kills
       the window that contained it.  If this window was in the foreground, the display switches to the previous window; if none are left, screen exits.

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

       Screen does not understand the prefix “C-” to mean control.  Please use the caret notation (“^A” instead of “C-a”) as arguments to e.g. the escape command
       or the -e option.  Screen will also print out control 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 com-
       mand 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 argu-
       ments to the window manager (specified in the $STY environment variable) who will use it to create the new window.  The  above  example  would  start  the
       emacs editor (editing prog.c) and switch to its window.

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

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 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 ?”.  Typing these two characters
       will  display  a  list  of the available screen commands and their bindings. Each keystroke is discussed in the section “DEFAULT KEY BINDINGS”. The manual
       section “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.

COMMAND-LINE OPTIONS
       Screen has the following command-line options:

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

       -A   Adapt the sizes of all windows to the size of the current terminal.  By default, screen tries to restore its  old  window  sizes  when  attaching  to
            resizable terminals (those with “WS” in its description, e.g. suncmd or some xterm).

       -c file
            override the default configuration file from “$HOME/.screenrc” to file.

       -d|-D [pid.tty.host]
            does  not  start screen, but detaches the elsewhere running screen session. It has the same effect as typing “C-a d” from screen’s controlling termi-
            nal. -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 always a good idea to check the status of your sessions by means of “screen -list”.

       -e xy
            specifies the command character to be x and the character generating a literal command character to y (when typed after the command character).   The
            default  is  “C-a”  and ‘a’, which can be specified as “-e^Aa”.  When creating a screen session, this option sets the default command character. In a
            multiuser session all users added will start off with this command character. But when attaching to an already running session, this  option  changes
            only the command character of the attaching user.  This option is equivalent to either the commands “defescape” or “escape” respectively.

       -f, -fn, and -fa
            turns flow-control on, off, or “automatic switching mode”.  This can also be defined through the “defflow” .screenrc command.

       -h num
            Specifies the history scrollback buffer to be num lines high.

       -i   will  cause  the  interrupt  key (usually C-c) to interrupt the display immediately when flow-control is on.  See the “defflow” .screenrc command for
            details.  The use of this option is discouraged.

       -l and -ln
            turns login mode on or off (for /etc/utmp updating).  This can also be defined through the “deflogin” .screenrc command.

       -ls and -list
            does not start screen, but prints a list of pid.tty.host strings identifying your screen sessions.  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’. Ses-
            sions marked as ‘unreachable’ either live on a different host or are ‘dead’.  An unreachable session is considered dead, when its name matches either
            the  name  of  the  local  host, or the specified parameter, if any.  See the -r flag for a description how to construct matches.  Sessions marked as
            ‘dead’ should be thoroughly checked and removed.  Ask your system administrator if you are not sure. Remove sessions with the -wipe option.

       -L   tells screen to turn on automatic output logging for the windows.

       -m   causes screen to ignore the $STY environment variable. With “screen -m” creation of a new session is enforced, regardless whether  screen  is  called
            from within another screen session or not. This flag has a special meaning in connection with the ‘-d’ option:

       -d -m   Start screen in “detached” mode. This creates a new session but doesn’t attach to it. This is useful for system startup scripts.

       -D -m   This also starts screen in “detached” mode, but doesn’t fork a new process. The command exits if the session terminates.

       -O   selects  a  more  optimal output mode for your terminal rather than true VT100 emulation (only affects auto-margin terminals without ‘LP’).  This can
            also be set in your .screenrc by specifying ‘OP’ in a “termcap” command.

       -p number_or_name
            Preselect a window. This is usefull when you want to reattach to a specific windor or you want to send a command via the “-X” option  to  a  specific
            window. As with screen’s select commant, “-” selects the blank window. As a special case for reattach, “=” brings up the windowlist on the blank win-
            dow.

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

       -r [pid.tty.host]
       -r sessionowner/[pid.tty.host]
            resumes  a  detached screen session.  No other options (except combinations with -d/-D) may be specified, though an optional prefix of [pid.]tty.host
            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   attempts  to  resume  the first detached screen session it finds.  If successful, all other command-line options are ignored.  If no detached session
            exists, starts a new session using the specified options, just as if -R had not been specified. The option is set by default if screen is  run  as  a
            login-shell (actually screen uses “-xRR” in that case).  For combinations with the -d/-D option see there.

       -s   sets  the  default  shell  to the program specified, instead of the value in the environment variable $SHELL (or “/bin/sh” if not defined).  This can
            also be defined through the “shell” .screenrc command.

       -S sessionname
            When creating a new session, this option can be used to specify a meaningful name for the session. This  name  identifies  the  session  for  “screen
            -list” and “screen -r” actions. It substitutes the default [tty.host] suffix.

       -t name
            sets the title (a.k.a.) for the default shell or specified program.  See also the “shelltitle” .screenrc command.

       -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 encod-
            ing for new windows to ‘utf8′.

       -v   Print version number.

       -wipe [match]
            does the same as “screen -ls”, but removes destroyed sessions instead of marking them as ‘dead’.  An unreachable session is considered dead, when its
            name  matches  either  the  name  of  the  local host, or the explicitly given parameter, if any.  See the -r flag for a description how to construct
            matches.

       -x   Attach to a not detached screen session. (Multi display mode).

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

DEFAULT KEY BINDINGS
       As  mentioned,  each  screen command consists of a “C-a” followed by one other character.  For your convenience, all commands that are bound to lower-case
       letters are also bound to their control character counterparts (with the exception of “C-a a”; see below), thus, “C-a c” as well as “C-a C-c” can be  used
       to create a window. See section “CUSTOMIZATION” for a description of the command.

       The following table shows the default key bindings:

       C-a ‘       (select)      Prompt for a window name or number to switch to.

       C-a ”       (windowlist -b)
                                 Present a list of all windows for selection.

       C-a 0       (select 0)
        …           …
       C-a 9       (select 9)
       C-a -       (select -)    Switch to window number 0 – 9, or to the blank window.

       C-a tab     (focus)       Switch the input focus to the next region.

       C-a C-a     (other)       Toggle  to  the window displayed previously.  Note that this binding defaults to the command character typed twice, unless over-
                                 ridden.  For instance, if you use the option “-e]x”, this command becomes “]]”.

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

       C-a A       (title)       Allow the user to enter a name for the current window.

       C-a b
       C-a C-b     (break)       Send a break to window.

       C-a B       (pow_break)   Reopen the terminal line and send a break.

       C-a c
       C-a C-c     (screen)      Create a new window with a shell and switch to that window.

       C-a C       (clear)       Clear the screen.

       C-a d
       C-a C-d     (detach)      Detach screen from this terminal.

       C-a D D     (pow_detach)  Detach and logout.

       C-a f
       C-a C-f     (flow)        Toggle flow on, off or auto.

       C-a F       (fit)         Resize the window to the current region size.

       C-a C-g     (vbell)       Toggles screen’s visual bell mode.

       C-a h       (hardcopy)    Write a hardcopy of the current window to the file “hardcopy.n”.

       C-a H       (log)         Begins/ends logging of the current window to the file “screenlog.n”.

       C-a i
       C-a C-i     (info)        Show info about this window.

       C-a k
       C-a C-k     (kill)        Destroy current window.

       C-a l
       C-a C-l     (redisplay)   Fully refresh current window.

       C-a L       (login)       Toggle this windows login slot. Available only if screen is configured to update the utmp database.

       C-a m
       C-a C-m     (lastmsg)     Repeat the last message displayed in the message line.

       C-a M       (monitor)     Toggles monitoring of the current window.

       C-a space
       C-a n
       C-a C-n     (next)        Switch to the next window.

       C-a N       (number)      Show the number (and title) of the current window.

       C-a backspace
       C-a h
       C-a p
       C-a C-p     (prev)        Switch to the previous window (opposite of C-a n).

       C-a q
       C-a C-q     (xon)         Send a control-q to the current window.

       C-a Q       (only)        Delete all regions but the current one.

       C-a r
       C-a C-r     (wrap)        Toggle the current window’s line-wrap setting (turn the current window’s automatic margins on and off).

       C-a s
       C-a C-s     (xoff)        Send a control-s to the current window.

       C-a S       (split)       Split the current region into two new ones.

       C-a t
       C-a C-t     (time)        Show system information.

       C-a v       (version)     Display the version and compilation date.

       C-a C-v     (digraph)     Enter digraph.

       C-a w
       C-a C-w     (windows)     Show a list of window.

       C-a W       (width)       Toggle 80/132 columns.

       C-a x
       C-a C-x     (lockscreen)  Lock this terminal.

       C-a X       (remove)      Kill the current region.

       C-a z
       C-a C-z     (suspend)     Suspend screen.  Your system must support BSD-style job-control.

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

       C-a .       (dumptermcap) Write out a “.termcap” file.

       C-a ?       (help)        Show key bindings.

       C-a C-\     (quit)        Kill all windows and terminate screen.

       C-a :       (colon)       Enter command line mode.

       C-a [
       C-a C-[
       C-a esc     (copy)        Enter copy/scrollback mode.

       C-a ]       (paste .)     Write the contents of the paste buffer to the stdin queue of the current window.

       C-a {
       C-a }       (history)     Copy and paste a previous (command) line.

       C-a >       (writebuf)    Write paste buffer to a file.

       C-a <       (readbuf)     Reads the screen-exchange file into the paste buffer.

       C-a =       (removebuf)   Removes the file used by C-a < and C-a >.

       C-a ,       (license)     Shows where screen comes from, where it went to and why you can use it.

       C-a _       (silence)     Start/stop monitoring the current window for inactivity.

       C-a *       (displays)    Show a listing of all currently attached displays.

CUSTOMIZATION
       The “socket directory” defaults either to $HOME/.screen or simply to /tmp/screens or preferably to /usr/local/screens chosen at compile-time. If screen is
       installed  setuid-root, then the administrator should compile screen with an adequate (not NFS mounted) socket directory. If screen is not running setuid-
       root, the user can specify any mode 700 directory in the environment variable $SCREENDIR.

       When screen is invoked, it executes initialization commands from the files “/etc/screenrc” and “.screenrc” in the user’s home  directory.  These  are  the
       “programmer’s  defaults”  that  can  be overridden in the following ways: for the global screenrc file screen searches for the environment variable $SYSS-
       CREENRC (this override feature may be disabled at compile-time). The user specific screenrc file is searched in $SCREENRC, then $HOME/.screenrc.  The com-
       mand line option -c takes precedence over the above user screenrc files.

       Commands  in  these  files  are  used  to set options, bind functions to keys, and to automatically establish one or more windows at the beginning of your
       screen session.  Commands are listed one per line, with empty lines being ignored.  A command’s arguments are separated by tabs or spaces, and may be sur-
       rounded  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  incompatibil-
       ity  with previous screen versions, as now the ‘$’-character has to be protected with ‘\’ if no variable substitution shall be performed. A string in sin-
       gle-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 exam-
       ples for various commands.

       Customization can also be done ‘on-line’. To enter the command mode type ‘C-a :’. Note that commands starting with “def” change default values, while oth-
       ers change current settings.

       The following commands are available:

       acladd usernames [crypted-pw]
       addacl usernames

       Enable users to fully access this screen session. Usernames can be one user or a comma separated list of users. This command  enables  to  attach  to  the
       screen  session  and  performs  the  equivalent of ‘aclchg usernames +rwx “#?”‘.  executed. To add a user with restricted access, use the ‘aclchg’ command
       below.  If an optional second parameter is supplied, it should be a crypted password for the named user(s). ‘Addacl’ is a synonym to ‘acladd’.  Multi user
       mode only.

       aclchg usernames permbits list
       chacl usernames permbits list

       Change  permissions  for  a  comma  separated list of users. Permission bits are represented as ‘r’, ‘w’ and ‘x’. Prefixing ‘+’ grants the permission, ‘-’
       removes it. The third parameter is a comma separated list of commands and/or windows (specified either by number or title). The special list ‘#’ refers to
       all  windows,  ‘?’  to all commands. if usernames consists of a single ‘*’, all known users are affected.  A command can be executed when the user has the
       ‘x’ bit for it.  The user can type input to a window when he has its ‘w’ bit set and no other user obtains a writelock for this window.   Other  bits  are
       currently  ignored.  To withdraw the writelock from another user in window 2: ‘aclchg username -w+w 2′.  To allow read-only access to the session: ‘aclchg
       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 win-
       dows. Execution permission for the acl commands, ‘at’ and others should also be removed or the user may be able to regain write permission.  Rights of the
       special username nobody cannot be changed (see the “su” command).  ‘Chacl’ is a synonym to ‘aclchg’.  Multi user mode only.

       acldel username

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

       aclgrp username [groupname]

       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.

       aclumask [[users]+bits |[users]-bits …. ]
       umask [[users]+bits |[users]-bits …. ]

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

       activity message

       When any activity occurs in a background window that is being monitored, screen displays a notification in the message line.  The notification message can
       be re-defined by means of the “activity” command.  Each occurrence of ‘%’ in message is replaced by the  number  of  the  window  in  which  activity  has
       occurred, and each occurrence of ‘^G’ is replaced by the definition for bell in your termcap (usually an audible bell).  The default message is

                   ‘Activity in window %n’

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

       allpartial on|off

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

       altscreen on|off

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

       at [identifier][#|*|%] command [args ... ]

       Execute  a command at other displays or windows as if it had been entered there.  “At” changes the context (the ‘current window’ or ‘current display’ set-
       ting) of the command. If the first parameter describes a non-unique context, the command will be executed multiple times. If the first parameter is of the
       form  ‘identifier*’  then  identifier  is matched against user names.  The command is executed once for each display of the selected user(s). If the first
       parameter is of the form ‘identifier%’ identifier is matched against displays. Displays are named after the  ttys  they  attach.  The  prefix  ‘/dev/’  or
       ‘/dev/tty’  may  be omitted from the identifier.  If identifier has a ‘#’ or nothing appended it is matched against window numbers and titles. Omitting an
       identifier in front of the ‘#’, ‘*’ or ‘%’-character selects all users, displays or windows because a prefix-match is performed. Note that on the affected
       display(s)  a  short message will describe what happened. Permission is checked for initiator of the “at” command, not for the owners of the affected dis-
       play(s).  Note that the ‘#’ character works as a comment introducer when it is preceded by whitespace. This can be escaped by prefixing a ‘\’.  Permission
       is checked for the initiator of the “at” command, not for the owners of the affected display(s).
       Caveat:  When  matching  against windows, the command is executed at least once per window. Commands that change the internal arrangement of windows (like
       “other”) may be called again. In shared windows the command will be repeated for each attached display. Beware, when issuing toggle commands like “login”!
       Some  commands  (e.g.  “process”)  require that a display is associated with the target windows.  These commands may not work correctly under “at” looping
       over windows.

       attrcolor attrib [attribute/color-modifier]

       This command can be used to highlight attributes by changing the color of the text. If the attribute attrib is in use, the specified attribute/color modi-
       fier  is also applied. If no modifier is given, the current one is deleted. See the “STRING ESCAPES” chapter for the syntax of the modifier. Screen under-
       stands two pseudo-attributes, “i” stands for high-intensity foreground color and “I” for high-intensity background color.

       Examples:

              attrcolor b “R”

       Change the color to bright red if bold text is to be printed.

              attrcolor u “-u b”

       Use blue text instead of underline.

              attrcolor b “.I”

       Use bright colors for bold text. Most terminal emulators do this already.

              attrcolor i “+b”

       Make bright colored text also bold.

       autodetach on|off

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

       autonuke on|off

       Sets whether a clear screen sequence should nuke all the output that has not been written to the terminal. See also “obuflimit”.

       backtick id lifespan autorefresh cmd args…
       backtick id

       Program  the  backtick  command  with the numerical id id.  The output of such a command is used for substitution of the “%’” string escape. The specified
       lifespan is the number of seconds the output is considered valid. After this time, the command is run again if a corresponding string  escape  is  encoun-
       tered.   The  autorefresh  parameter triggers an automatic refresh for caption and hardstatus strings after the specified number of seconds. Only the last
       line of output is used for substitution.
       If both the lifespan and the autorefresh parameters are zero, the backtick program is expected to stay in the background and generate  output  once  in  a
       while.   In  this case, the command is executed right away and screen stores the last line of output. If a new line gets printed screen will automatically
       refresh the hardstatus or the captions.
       The second form of the command deletes the backtick command with the numerical id id.

       bce [on|off]

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

       bell_msg [message]

       When  a  bell character is sent to a background window, screen displays a notification in the message line.  The notification message can be re-defined by
       this command.  Each occurrence of ‘%’ in message is replaced by the number of the window to which a bell has been sent, and each  occurrence  of  ‘^G’  is
       replaced by the definition for bell in your termcap (usually an audible bell).  The default message is

                   ‘Bell in window %n’

       An  empty message can be supplied to the “bell_msg” command to suppress output of a message line (bell_msg “”).  Without parameter, the current message is
       shown.

       bind [-c class] key [command [args]]

       Bind a command to a key.  By default, most of the commands provided by screen are bound to one or more keys as indicated in  the  “DEFAULT  KEY  BINDINGS”
       section, e.g. 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.  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 num-
       ber  (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 listed
       in this section.

       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.

       Some examples:

                   bind ‘ ‘ windows
                   bind ^k
                   bind k
                   bind K kill
                   bind ^f screen telnet foobar
                   bind \033 screen -ln -t root -h 1000 9 su

       would bind the space key to the command that displays a list of windows (so that the command usually invoked by “C-a C-w” would also be available as  “C-a
       space”).  The next three lines remove the default kill binding from “C-a C-k” and “C-a k”.  “C-a K” is then bound to the kill command. Then it binds “C-f”
       to the command “create a window with a TELNET connection to foobar”, and bind “escape” to the command that creates an non-login window with a.k.a.  “root”
       in slot #9, with a superuser shell and a scrollback buffer of 1000 lines.

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

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

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

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

       bindkey [-d] [-m] [-a] [[-k|-t] string [cmd args]]

       This  command manages screen’s input translation tables. Every entry in one of the tables tells screen how to react if a certain sequence of characters is
       encountered. There are three tables: one that should contain actions programmed by the user, one for the default actions used for terminal  emulation  and
       one for screen’s copy mode to do cursor movement. See section “INPUT TRANSLATION” for a list of default key bindings.
       If  the  -d  option  is given, bindkey modifies the default table, -m changes the copy mode table and with neither option the user table is selected.  The
       argument string is the sequence of characters to which an action is bound. This can either be a  fixed  string  or  a  termcap  keyboard  capability  name
       (selectable with the -k option).
       Some  keys  on  a  VT100  terminal  can send a different string if application mode is turned on (e.g the cursor keys).  Such keys have two entries in the
       translation table. You can select the application mode entry by specifying the -a option.
       The -t option tells screen not to do inter-character timing. One cannot turn off the timing if a termcap 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.
       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 “^T” an escape character for key-bindings. If you did the above “stuff barfoo” binding, you can enter  the  word  “foo”  by  typing
       “^Tfoo”. If you want to insert a “^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 ^A).

       break [duration]

       Send  a break signal for duration*0.25 seconds to this window.  For non-Posix systems the time interval may be rounded up to full seconds.  Most useful if
       a character device is attached to the window rather than a shell process (See also chapter “WINDOW TYPES”). The maximum duration of a break signal is lim-
       ited to 15 seconds.

       blanker

       Activate  the  screen  blanker. First the screen is cleared. If no blanker program is defined, the cursor is turned off, otherwise, the program is started
       and it’s output is written to the screen.  The screen blanker is killed with the first keypress, the read key is discarded.
       This command is normally used together with the “idle” command.

       blankerprg [program args]

       Defines a blanker program. Disables the blanker program if no arguments are given.

       breaktype [tcsendbreak|TIOCSBRK |TCSBRK]

       Choose one of the available methods of generating a break signal for terminal devices. This command should affect the current window only.  But  it  still
       behaves  identical to “defbreaktype”. This will be changed in the future.  Calling “breaktype” with no parameter displays the break method for the current
       window.

       bufferfile [exchange-file]

       Change the filename used for reading and writing with the paste buffer.  If the optional argument to the “bufferfile” command is omitted, the default set-
       ting (“/tmp/screen-exchange”) is reactivated.  The following example will paste the system’s password file into the screen window (using the paste buffer,
       where a copy remains):

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

       c1 [on|off]

       Change c1 code processing. “C1 on” tells screen to treat the input characters between 128 and 159 as control functions.  Such an 8-bit  code  is  normally
       the  same  as ESC followed by the corresponding 7-bit code. The default setting is to process c1 codes and can be changed with the “defc1″ command.  Users
       with fonts that have usable characters in the c1 positions may want to turn this off.

       caption always|splitonly [string]
       caption string [string]

       This command controls the display of the window captions. Normally a caption is only used if more than one window is shown on the  display  (split  screen
       mode). But if the type is set to always screen shows a caption even if only one window is displayed. The default is splitonly.

       The second form changes the text used for the caption. You can use all escapes from the “STRING ESCAPES” chapter. Screen uses a default of ‘%3n %t’.

       You can mix both forms by providing a string as an additional argument.

       charset set

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

       chdir [directory]

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

       clear

       Clears the current window and saves its image to the scrollback buffer.

       colon [prefix]

       Allows you to enter “.screenrc” command lines. Useful for on-the-fly modification of key bindings, specific window creation and  changing  settings.  Note
       that  the “set” keyword no longer exists! Usually commands affect the current window rather than default settings for future windows. Change defaults with
       commands starting with ‘def…’.

       If you consider this as the ‘Ex command mode’ of screen, you may regard “C-a esc” (copy mode) as its ‘Vi command mode’.

       command [-c class]

       This command has the same effect as typing the screen escape character (^A). It is probably only useful for key bindings.  If the “-c”  option  is  given,
       select the specified command class.  See also “bind” and “bindkey”.

       compacthist [on|off]

       This tells screen whether to suppress trailing blank lines when scrolling up text into the history buffer.

       console [on|off]

       Grabs or un-grabs the machines console output to a window.  Note: Only the owner of /dev/console can grab the console output.  This command is only avail-
       able if the machine supports the ioctl TIOCCONS.

       copy

       Enter copy/scrollback mode. This allows you to copy text from the current window and its history into the paste buffer.  In  this  mode  a  vi-like  ‘full
       screen editor’ is active:
       Movement keys:
         h, j, k, l move the cursor line by line or column by column.
         0, ^ and $ move to the leftmost column, to the first or last non-whitespace character on the line.
         H, M and L move the cursor to the leftmost column of the top, center or bottom line of the window.
         + and – positions one line up and down.
         G moves to the specified absolute line (default: end of buffer).
         | moves to the specified absolute column.
         w, b, e move the cursor word by word.
         B, E move the cursor WORD by WORD (as in vi).
         C-u and C-d scroll the display up/down by the specified amount of lines while preserving the cursor position. (Default: half screen-full).
         C-b and C-f scroll the display up/down a full screen.
         g moves to the beginning of the buffer.
         % jumps to the specified percentage of the buffer.

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

       Marking:
           The copy range is specified by setting two marks. The text between these marks will be highlighted. Press
         space to set the first or second mark respectively.
         Y and y used to mark one whole line or to mark from start of line.
         W marks exactly one word.
       Repeat count:
           Any of these commands can be prefixed with a repeat count number by pressing digits
         0..9 which is taken as a repeat count.
           Example: “C-a C-[ H 10 j 5 Y" will copy lines 11 to 15 into the paste buffer.
       Searching:
         / Vi-like search forward.
         ? Vi-like search backward.
         C-a s Emacs style incremental search forward.
         C-r Emacs style reverse i-search.
       Specials:
           There are however some keys that act differently than in vi.  Vi does not allow one to yank rectangular blocks of text, but screen does. Press
         c or C to set the left or right margin respectively. If no repeat count is given, both default to the 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 whitespace
           and comma separated lines. Note that you can prepend the newline character with a carriage return character, by issuing a "crlf on".
         v is for all the vi users with ":set numbers" - it toggles the left margin between column 9 and 1. Press
         a before the final space key to toggle in append mode. Thus the contents of the paste buffer will not be overwritten, but is appended to.
         A toggles in append mode and sets a (second) mark.
         > sets the (second) mark and writes the contents of the paste buffer to the screen-exchange file (/tmp/screen-exchange per default)  once  copy-mode  is
           finished.
           This example demonstrates how to dump the whole scrollback buffer to that file: "C-A [ g SPACE G $ >".
         C-g gives information about the current line and column.
         x exchanges the first mark and the current cursor position. You can use this to adjust an already placed mark.
         @ does nothing. Does not even exit copy mode.
         All keys not described here exit copy mode.

       copy_reg [key]

       No longer exists, use “readreg” instead.

       crlf [on|off]

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

       debug on|off

       Turns runtime debugging on or off. If screen has been compiled with option -DDEBUG debugging available and is turned on per default. Note that  this  com-
       mand only affects debugging output from the main "SCREEN" process correctly. Debug output from attacher processes can only be turned off once and forever.

       defc1 on|off

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

       defautonuke on|off

       Same as the autonuke command except that the default setting for new displays is changed. Initial setting is 'off'.  Note that you  can  use  the  special
       'AN' terminal capability if you want to have a dependency on the terminal type.

       defbce on|off

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

       defbreaktype [tcsendbreak|TIOCSBRK |TCSBRK]

       Choose  one  of  the  available methods of generating a break signal for terminal devices. The preferred methods are tcsendbreak and TIOCSBRK.  The third,
       TCSBRK, blocks the complete screen session for the duration of the break, but it may be the only way to generate long breaks.   Tcsendbreak  and  TIOCSBRK
       may  or  may  not  produce long breaks with spikes (e.g. 4 per second). This is not only system dependant, this also differs between serial board drivers.
       Calling “defbreaktype” with no parameter displays the current setting.

       defcharset [set]

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

       defescape xy

       Set the default command characters. This is equivalent to the “escape” except that it is useful multiuser 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.

       defflow on|off|auto [interrupt]

       Same  as  the  flow command except that the default setting for new windows is changed. Initial setting is ‘auto’.  Specifying “defflow auto interrupt” is
       the same as the command-line options -fa and -i.

       defgr on|off

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

       defhstatus [status]

       The hardstatus line that all new windows will get is set to status.  This command is useful to make the hardstatus of every window display the window num-
       ber  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 cur-
       rent default string is displayed.  Per default the hardstatus line of new windows is empty.

       defencoding enc

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

       deflog on|off

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

       deflogin on|off

       Same as the login command except that the default setting for new windows is changed. This is initialized with ‘on’ as distributed (see config.h.in).

       defmode mode

       The mode of each newly allocated pseudo-tty is set to mode.  Mode is an octal number.  When no “defmode” command is given, mode 0622 is used.

       defmonitor on|off

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

       defnonblock on|off|numsecs

       Same as the nonblock command except that the default setting for displays is changed. Initial setting is ‘off’.

       defobuflimit limit

       Same  as  the obuflimit command except that the default setting for new displays is changed. Initial setting is 256 bytes.  Note that you can use the spe-
       cial ‘OL’ terminal capability if you want to have a dependency on the terminal type.

       defscrollback num

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

       defshell command

       Synonym to the shell command. See there.

       defsilence on|off

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

       defslowpaste msec”

       Same as the slowpaste command except that the default setting for new windows is changed. Initial setting is 0 milliseconds, meaning ‘off’.

       defutf8 on|off

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

       defwrap on|off

       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”.

       defwritelock on|off|auto

       Same as the writelock command except that the default setting for new windows is changed. Initially writelocks will off.

       defzombie [keys]

       Synonym to the zombie command. Both currently change the default.  See there.

       detach [-h]

       Detach the screen session (disconnect it from the terminal and put it into the background).  This returns you to the shell where you  invoked  screen.   A
       detached  screen can be resumed by invoking screen with the -r option (see also section “COMMAND-LINE OPTIONS”). The -h option tells screen to immediately
       close the connection to the terminal (“hangup”).

       dinfo

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

       displays

       Shows a tabular listing of all currently connected user front-ends (displays).  This is most useful for multiuser sessions.

       digraph [preset]

       This command prompts the user for a digraph sequence. The next two characters typed are looked up in a  builtin  table  and  the  resulting  character  is
       inserted  in  the  input  stream. For example, if the user enters ‘a”‘, an a-umlaut will be inserted. If the first character entered is a 0 (zero), screen
       will treat the following 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.

       dumptermcap

       Write  the termcap entry for the virtual terminal optimized for the currently active window to the file “.termcap” in the user’s “$HOME/.screen” directory
       (or wherever screen stores its sockets. See the “FILES” section below).  This termcap entry is identical to the value of the environment variable $TERMCAP
       that  is set up by screen for each window. For terminfo based systems you will need to run a converter like captoinfo and then compile the entry with tic.

       echo [-n] message

       The echo command may be used to annoy screen users with a ‘message of the day’. Typically installed in a global /etc/screenrc.  The  option  “-n”  may  be
       used to suppress the line feed.  See also “sleep”.  Echo is also useful for online checking of environment variables.

       encoding enc [enc]

       Tell  screen  how to interpret the input/output. The first argument sets the encoding of the current window. Each window can emulate a different encoding.
       The optional second parameter overwrites the encoding of the connected terminal. It should never be needed as screen uses the locale setting to detect the
       encoding.  There is also a way to select a terminal encoding depending on the terminal type by using the “KJ” termcap entry.

       Supported  encodings  are  eucJP,  SJIS, eucKR, eucCN, Big5, GBK, KOI8-R, CP1251, UTF-8, ISO8859-2, ISO8859-3, ISO8859-4, ISO8859-5, ISO8859-6, ISO8859-7,
       ISO8859-8, ISO8859-9, ISO8859-10, ISO8859-15, jis.

       See also “defencoding”, which changes the default setting of a new window.

       escape xy

       Set the command character to x and the character generating a literal command character (by triggering the  “meta”  command)  to  y  (similar  to  the  -e
       option).   Each  argument is either a single character, a two-character sequence of the form “^x” (meaning “C-x”), a backslash followed by an octal number
       (specifying the ASCII code of the character), or a backslash followed by a second character, such as “\^” or “\\”.  The default is “^Aa”.

       eval command1 [command2 ...]

       Parses and executes each argument as separate command.

       exec [[fdpat] newcommand [args ...]]

       Run a unix subprocess (specified by an executable path newcommand and its optional arguments) in the current window. The flow of data between  newcommands
       stdin/stdout/stderr,  the  process originally started in the window (let us call it “application-process”) and screen itself (window) is controlled by the
       filedescriptor pattern fdpat.  This pattern is basically a three character sequence representing stdin, stdout and stderr of newcommand. A  dot  (.)  con-
       nects  the file descriptor to screen.  An exclamation mark (!) causes the file descriptor to be connected to the application-process. A colon (:) combines
       both.  User input will go to newcommand unless newcommand receives the application-process’ output (fdpats first character is ‘!’ or ‘:’) or a pipe symbol
       (|) is added (as a fourth character) to the end of fdpat.
       Invoking  ‘exec’  without arguments shows name and arguments of the currently running subprocess in this window. Only one subprocess a time can be running
       in each window.
       When a subprocess is running the ‘kill’ command will affect it instead of the windows process.
       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 the 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.

       Abbreviations:
       Whitespace between the word ‘exec’ and fdpat and the command 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 here and can always be replaced by ‘!’.

       Examples:

              exec … /bin/sh
              exec /bin/sh
              !/bin/sh

       Creates  another shell in the same window, while the original shell is still running. Output of both shells is displayed and user input is sent to the new
       /bin/sh.

              exec !.. stty 19200
              exec ! stty 19200
              !!stty 19200

       Set the speed of the window’s tty. If your stty command operates on stdout, then add another ‘!’.

              exec !..| less
              |less

       This adds a pager to the window output. The special character ‘|’ is needed to give the user control over the pager although it gets its  input  from  the
       window’s  process. This works, because less listens on stderr (a behavior that screen would not expect without the ‘|’) when its stdin is not a tty.  Less
       versions newer than 177 fail miserably here; good old pg still works.

              !:sed -n s/.*Error.*/\007/p

       Sends window output to both, the user and the sed command. The sed inserts an additional bell character (oct. 007) to the window output  seen  by  screen.
       This will cause “Bell in window x” messages, whenever the string “Error” appears in the window.

       fit

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

       flow [on|off|auto]

       Sets the flow-control mode for this window.  Without parameters it cycles the current window’s flow-control setting from “automatic”  to  “on”  to  “off”.
       See  the  discussion on “FLOW-CONTROL” later on in this document for full details and note, that this is subject to change in future releases.  Default is
       set by ‘defflow’.

       focus [up|down|top|bottom]

       Move the input focus to the next region. This is done in a cyclic way so that the top region is selected after the bottom one. If no subcommand  is  given
       it defaults to ‘down’. ‘up’ cycles in the opposite order, ‘top’ and ‘bottom’ go to the top and bottom region respectively. Useful bindings are (j and k as
       in vi)
           bind j focus down
           bind k focus up
           bind t focus top
           bind b focus bottom

       gr [on|off]

       Turn GR charset switching on/off. Whenever screen sees an input character with the 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.

       hardcopy [-h] [file]

       Writes out the currently displayed image to the file file, or, if no filename is specified, to hardcopy.n in the default directory, where n is the  number
       of  the current window.  This either appends or overwrites the file if it exists. See below.  If the option -h is specified, dump also the contents of the
       scrollback buffer.

       hardcopy_append on|off

       If set to “on”, screen will append to the “hardcopy.n” files created by the command “C-a h”, otherwise these files are overwritten each time.  Default  is
       ‘off’.

       hardcopydir directory

       Defines a directory where hardcopy files will be placed. If unset, hardcopys are dumped in screen’s current working directory.

       hardstatus [on|off]
       hardstatus [always]lastline|message|ignore [string]
       hardstatus string [string]

       This  command  configures the use and emulation of the terminal’s hardstatus line. The first form toggles whether screen will use the hardware status line
       to display messages. If the flag is set to ‘off’, these messages are overlaid in reverse video mode at the display line. The default setting is ‘on’.

       The second form tells screen what to do if the terminal doesn’t have a hardstatus line (i.e. the termcap/terminfo capabilities “hs”, “ts”, “fs”  and  “ds”
       are  not set). If the type “lastline” is used, screen will reserve the last line of the display for the hardstatus. “message” uses screen’s message mecha-
       nism and “ignore” tells screen never to display the hardstatus.  If you prepend the word “always” to the type (e.g., “alwayslastline”),  screen  will  use
       the type even if the terminal supports a hardstatus.

       The  third form specifies the contents of the hardstatus line.  ‘%h’ is used as default string, i.e. the stored hardstatus of the current window (settable
       via “ESC]0;<string>^G” or “ESC_<string>ESC\”) is displayed.  You can customize this to any string you like including the escapes from the “STRING ESCAPES”
       chapter. If you leave out the argument string, the current string is displayed.

       You can mix the second and third form by providing the string as additional argument.

       height [-w|-d] [lines [cols]]

       Set  the display height to a specified number of lines. When no argument is given it toggles between 24 and 42 lines display. You can also specify a width
       if you want to change both values.  The -w option tells screen to leave the display size unchanged and just set the window size, -d vice versa.

       help [-c class]

       Not really a online help, but displays a help screen showing you all the key bindings.  The first pages list all the internal commands followed  by  their
       current  bindings.   Subsequent pages will display the custom 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.  See also “DEFAULT
       KEY BINDINGS” section.

       history

       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 allows you to have a primitive way of re-calling “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).

       hstatus status

       Change the window’s hardstatus line to the string status.

       idle [timeout [cmd args]]

       Sets a command that is run after the specified number of seconds inactivity is reached. This command will normally be the “blanker” command  to  create  a
       screen  blanker,  but  it  can be any screen command.  If no command is specified, only the timeout is set. A timeout of zero (ot the special timeout off)
       disables the timer.  If no arguments are given, the current settings are displayed.

       ignorecase [on|off]

       Tell screen to ignore the case of characters in searches. Default is ‘off’.

       info

       Uses the message line to display some information about the current window: the cursor position in the form “(column,row)” starting with “(1,1)”, the ter-
       minal  width  and height plus the size of the scrollback buffer in lines, like in “(80,24)+50″, the current state of window XON/XOFF flow control is shown
       like this (See also section FLOW CONTROL):

         +flow     automatic flow control, currently on.
         -flow     automatic flow control, currently off.
         +(+)flow  flow control enabled. Agrees with automatic control.
         -(+)flow  flow control disabled. Disagrees with automatic control.
         +(-)flow  flow control enabled. Disagrees with automatic control.
         -(-)flow  flow control disabled. Agrees with automatic control.

       The current line wrap setting (‘+wrap’ indicates enabled, ‘-wrap’ not) is also shown. The flags ‘ins’, ‘org’, ‘app’, ‘log’, ‘mon’ or ‘nored’ are displayed
       when the window is in insert mode, origin mode, application-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
       is shown. If the window is in UTF-8 mode, the string “UTF-8″ is shown instead.

       Additional modes depending on the type of the window are displayed at the end of the status line (See also chapter “WINDOW TYPES”).
       If the state machine of the terminal emulator is in a non-default state, the info line is started with a string identifying the current state.
       For system information use the “time” command.

       ins_reg [key]

       No longer exists, use “paste” instead.

       kill

       Kill current window.
       If there is an ‘exec’ command running then it is killed. Otherwise the process (shell) running in the window  receives  a  HANGUP  condition,  the  window
       structure is removed and screen (your display) switches to another window.  When the last window is destroyed, screen exits.  After a kill screen switches
       to the previously displayed window.
       Note: Emacs users should keep this command in mind, when killing a line.  It is recommended not to use “C-a” as the screen escape key or to rebind kill to
       “C-a K”.

       lastmsg

       Redisplay  the  last contents of the message/status line.  Useful if you’re typing when a message appears, because  the message goes away when you press a
       key (unless your terminal has a hardware status line).  Refer to the commands “msgwait” and “msgminwait” for fine tuning.

       license

       Display the disclaimer page. This is done whenever screen is started without options, which should be often enough. See also  the  “startup_message”  com-
       mand.

       lockscreen

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

       log [on|off]

       Start/stop  writing  output  of the current window to a file “screenlog.n” in the window’s default directory, where n is the number of the current window.
       This filename can be changed with the ‘logfile’ command. If no parameter is given, the state of logging is toggled. The session log  is  appended  to  the
       previous  contents  of the file if it already exists. The current contents and the contents of the scrollback history are not included in the session log.
       Default is ‘off’.

       logfile filename
       logfile flush secs

       Defines the name the logfiles will get. The default is “screenlog.%n”. The second form changes the number of seconds screen will wait before flushing  the
       logfile buffer to the file-system. The default value is 10 seconds.

       login [on|off]

       Adds  or removes the entry in the utmp database file for the current window.  This controls if the window is ‘logged in’.  When no parameter is given, the
       login state of the window is toggled.  Additionally to that toggle, it is convenient having a ‘log in’ and a ‘log out’ key. E.g. ‘bind  I  login  on’  and
       ‘bind O login off’ will map these keys to be C-a I and C-a O.  The default setting (in config.h.in) should be “on” for a screen that runs under suid-root.
       Use the “deflogin” command to change the default login state for new windows. Both commands are only present when screen has been compiled with utmp  sup-
       port.

       logtstamp [on|off]
       logtstamp after [secs]
       logtstamp string [string]

       This  command  controls  logfile  time-stamp mechanism of screen.  If time-stamps are turned “on”, screen adds a string containing the current time to the
       logfile after two minutes of inactivity.  When output continues and more than another two minutes have passed, a second time-stamp is  added  to  document
       the  restart  of the output. You can change this timeout with the second form of the command. The third form is used for customizing the time-stamp string
       (‘– %n:%t — time-stamp — %M/%d/%y %c:%s –\n’ by default).

       mapdefault

       Tell screen that the next input character should only be looked up in the default bindkey table. See also “bindkey”.

       mapnotnext

       Like mapdefault, but don’t even look in the default bindkey table.

       maptimeout [timo]

       Set the inter-character timer for input sequence detection to a timeout of timo ms. The default timeout is 300ms. Maptimeout with no arguments  shows  the
       current setting.  See also “bindkey”.

       markkeys string

       This  is  a method of changing the keymap used for copy/history mode.  The string is made up of oldchar=newchar pairs which are separated by ‘:’. Example:
       The string “B=^B:F=^F” will change the keys ‘C-b’ and ‘C-f’ to the vi style binding (scroll up/down fill page).  This happens to be  the  default  binding
       for  ‘B’ and ‘F’.  The command “markkeys h=^B:l=^F:$=^E” would set the mode for an emacs-style binding.  If your terminal sends 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.

       maxwin num

       Set the maximum window number screen will create. Doesn’t affect already existing windows. The number may only be decreased.

       meta

       Insert the command character (C-a) in the current window’s input stream.

       monitor [on|off]

       Toggles activity monitoring of windows.  When monitoring is turned on and an affected window is switched into the background, you will receive the  activ-
       ity notification message in the status line at the first sign of output and the window will also be marked with an ‘@’ in the window-status display.  Mon-
       itoring is initially off for all windows.

       msgminwait sec

       Defines the time screen delays a new message when one message is currently displayed.  The default is 1 second.

       msgwait sec

       Defines the time a message is displayed if screen is not disturbed by other activity. The default is 5 seconds.

       multiuser on|off

       Switch between singleuser and multiuser mode. Standard screen operation is singleuser. In multiuser mode the commands  ‘acladd’,  ‘aclchg’,  ‘aclgrp’  and
       ‘acldel’ can be used to enable (and disable) other users accessing this screen session.

       nethack on|off

       Changes  the  kind  of  error messages used by screen.  When you are familiar with the game “nethack”, you may enjoy the nethack-style messages which will
       often blur the facts a little, but are much funnier to read. Anyway, standard messages often tend to be unclear as well.
       This option is only available if screen was compiled with the NETHACK flag defined. The default setting is then determined by the presence of the environ-
       ment variable $NETHACKOPTIONS.

       next

       Switch to the next window.  This command can be used repeatedly to cycle through the list of windows.

       nonblock [on|off|numsecs]

       Tell  screen  how to deal with user interfaces (displays) that cease to accept output. This can happen if a user presses ^S or a TCP/modem connection gets
       cut but no hangup is received. If nonblock is off (this is the default) screen waits until the display restarts to accept the output. If nonblock  is  on,
       screen  waits  until  the timeout is reached (on is treated as 1s). If the display still doesn’t receive characters, screen will consider it “blocked” and
       stop sending characters to it. If at some time it restarts to accept characters, screen will unblock the display and redisplay  the  updated  window  con-
       tents.

       number [n]

       Change  the current windows number. If the given number n is already used by another window, both windows exchange their numbers. If no argument is speci-
       fied, the current window number (and title) is shown.

       obuflimit [limit]

       If the output buffer contains more bytes than the specified limit, no more data will be read from the windows. The default value is 256.  If  you  have  a
       fast display (like xterm), you can set it to some higher value. If no argument is specified, the current setting is displayed.

       only

       Kill all regions but the current one.

       other

       Switch to the window displayed previously. If this window does no longer exist, other has the same effect as next.

       partial on|off

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

       password [crypted_pw]

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

       paste [registers [dest_reg]]

       Write the (concatenated) contents of the specified registers to the stdin queue of the current window. The register ‘.’ is treated as the paste buffer. If
       no  parameter  is  given the user is prompted for a single register to paste.  The paste buffer can be filled with the copy, history and readbuf commands.
       Other registers can be filled with the register, readreg and paste commands.  If paste is called with a second argument, the  contents  of  the  specified
       registers  is  pasted  into the named destination register rather than the window. If ‘.’ is used as the second argument, the displays paste buffer is the
       destination.  Note, that “paste” uses a wide variety of resources: 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.

       pastefont [on|off]

       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.

       pow_break

       Reopen the window’s terminal line and send a break condition. See ‘break’.

       pow_detach

       Power  detach.   Mainly  the  same as detach, but also sends a HANGUP signal to the parent process of screen.  CAUTION: This will result in a logout, when
       screen was started from your login shell.

       pow_detach_msg [message]

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

       prev

       Switch to the window with the next lower number.  This command can be used repeatedly to cycle through the list of windows.

       printcmd [cmd]

       If  cmd  is not an empty string, screen will not use the terminal capabilities “po/pf” if it detects an ansi print sequence ESC [ 5 i, but pipe the output
       into cmd.  This should normally be a command like "lpr" or "'cat > /tmp/scrprint'".  printcmd without a command displays the current  setting.   The  ansi
       sequence ESC \ ends printing and closes the pipe.
       Warning: Be careful with this command! If other user have write access to your terminal, they will be able to fire off print commands.

       process [key]

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

       quit

       Kill all windows and terminate screen.  Note that on VT100-style terminals the keys C-4 and C-\ are identical.  This makes the default bindings dangerous:
       Be careful not to type C-a C-4 when selecting window no. 4.  Use the empty bind command (as in “bind ‘^\’”) to remove a key binding.

       readbuf [-e encoding] [filename]

       Reads the contents of the specified file into the paste buffer.  You can tell screen the encoding of the file via the -e option.  If no file is specified,
       the screen-exchange filename is used.  See also “bufferfile” command.

       readreg [-e encoding] [register [filename]]

       Does one of two things, dependent on number of arguments: with zero or one arguments it it duplicates the paste buffer contents into the  register  speci-
       fied  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

       redisplay

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

       register [-e encoding] key string

       Save the specified string to the register key.  The encoding of the string can be specified via the -e option.  See also the “paste” command.

       remove

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

       removebuf

       Unlinks the screen-exchange file used by the commands “writebuf” and “readbuf”.

       reset

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

       resize

       Resize the current region. The space will be removed from or added to the region below or if there’s not enough space from the region above.

              resize +N   increase current region height by N

              resize -N   decrease current region height by N

              resize  N   set current region height to N

              resize  =   make all windows equally high

              resize  max maximize current region height

              resize  min minimize current region height

       screen [-opts] [n] [cmd [args]]

       Establish a new window.  The flow-control options (-f, -fn and -fa), title (a.k.a.) option (-t), login options (-l and -ln) ,  terminal  type  option  (-T
       <term>),  the  all-capability-flag (-a) and scrollback option (-h <num>) may be specified with each command.  The option (-M) turns monitoring on for this
       window.  The option (-L) turns output logging on for this window.  If an optional number n in the range 0..9 is given, the window number n is assigned  to
       the  newly created window (or, if this number is already in-use, the next available number).  If a command is specified after “screen”, this command (with
       the given arguments) is started in the window; otherwise, a shell is created.  Thus, if your “.screenrc” contains the lines

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

       screen creates a shell window (in window #1) and a window with a TELNET connection to the machine foobar (with no flow-control using the title “foobar” in
       window  #2) and will write a logfile (“screenlog.2″) of the telnet session.  Note, that unlike previous versions of screen no additional default window is
       created when “screen” commands are included in your “.screenrc” file. When the initialization is completed, screen switches to the last  window  specified
       in your .screenrc file or, if none, opens a default window #0.
       Screen has built in some functionality of “cu” and “telnet”.  See also chapter “WINDOW TYPES”.

       scrollback num

       Set the size of the scrollback buffer for the current windows to num lines. The default scrollback is 100 lines.  See also the “defscrollback” command and
       use “C-a i” to view the current setting.

       select [WindowID]

       Switch to the window identified by WindowID.  This can be a prefix of a window title (alphanumeric window name) or a  window  number.   The  parameter  is
       optional  and  if  omitted,  you get prompted for an identifier.  When a new window is established, the first available number is assigned to this window.
       Thus, the first window can be activated by “select 0″.  The number of windows is limited at compile-time by the MAXWIN configuration parameter.  There are
       two special WindowIDs, “-” selects the internal blank window and “.” selects the current window. The latter is useful if used with screen’s “-X” option.

       sessionname [name]

       Rename  the current session. Note, that for “screen -list” the name shows up with the process-id prepended. If the argument “name” is omitted, the name of
       this session is displayed. Caution: The $STY environment variables still reflects the old name. This may result in confusion.  The default is  constructed
       from the tty and host names.

       setenv [var [string]]

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

       setsid [on|off]

       Normally screen uses different sessions and process groups for the windows. If setsid is turned off, this is not done anymore and all windows will  be  in
       the same process group as the screen backend process. This also breaks job-control, so be careful.  The default is on, of course. This command is probably
       useful only in rare circumstances.

       shell command

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

       shelltitle title

       Set the title for all shells created during startup or by the C-A C-c command.  For details about what a title is, see  the  discussion  entitled  “TITLES
       (naming windows)”.

       silence [on|off|sec]

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

       silencewait sec

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

       sleep num

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

       slowpaste msec

       Define the speed at which text is inserted into the current window by the paste (“C-a ]”) command.  If the slowpaste value  is  nonzero  text  is  written
       character  by  character.   screen will make a pause of msec milliseconds after each single character write to allow the application to process its input.
       Only use slowpaste if your underlying system exposes flow control problems while pasting large amounts of text.

       source file

       Read and execute commands from file file. Source commands may be nested to a maximum recursion level of ten. If file is not an absolute path and screen is
       already  processing  a  source command, the parent directory of the running source command file is used to search for the new command file before screen’s
       current directory.

       Note that termcap/terminfo/termcapinfo commands only work at startup and reattach time, so they must be reached via the default screenrc files to have  an
       effect.

       sorendition [attr [color]]

       Change  the  way  screen does highlighting for text marking and printing messages.  See the “STRING ESCAPES” chapter for the syntax of the modifiers.  The
       default is currently “=s dd” (standout, default colors).

       split

       Split the current region into two new ones. All regions on the display are resized to make room for the new region. The blank window is displayed  on  the
       new region. Use the “remove” or the “only” command to delete regions.

       startup_message on|off

       Select whether you want to see the copyright notice during startup.  Default is ‘on’, as you probably noticed.

       stuff string

       Stuff  the string string in the input buffer of the current window.  This is like the “paste” command but with much less overhead.  You cannot paste large
       buffers with the “stuff” command. It is most useful for key bindings. See also “bindkey”.

       su [username [password [password2]]

       Substitute the user of a display. The command prompts for all parameters that are omitted. If passwords are specified as parameters, they have to be spec-
       ified  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”.

       suspend

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

       term term

       In  each  window’s  environment  screen opens, the $TERM variable is set to “screen” by default.  But when no description for “screen” is installed in the
       local termcap or terminfo data base, you set $TERM to – say – “vt100″. This won’t do much harm, as screen is VT100/ANSI compatible.  The use of the “term”
       command is discouraged for non-default purpose.  That is, one may want to specify special $TERM settings (e.g. vt100) for the next “screen rlogin otherma-
       chine” command. Use the command “screen -T vt100 rlogin othermachine” rather than setting and resetting the default.

       termcap term terminal-tweaks [window-tweaks]
       terminfo term terminal-tweaks [window-tweaks]
       termcapinfo term terminal-tweaks [window-tweaks]

       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 meaning-
       less once the terminal emulator is booted.
       If your system works 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 termcap names of the capabilities have to be used with the ‘terminfo’ command.
       In many cases, where the arguments are valid in both terminfo and termcap syntax, you can use the command ‘termcapinfo’, which is just a shorthand  for  a
       pair of ‘termcap’ and ‘terminfo’ commands with identical arguments.

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

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

       Some examples:

              termcap xterm*  LP:hs@

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

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

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

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

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

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

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

       If you would like to fully specify each window's termcap entry, you should instead set the $SCREENCAP variable prior to running screen.  See  the  discus-
       sion on the "VIRTUAL TERMINAL" in this manual, and the termcap(5) man page for more information on termcap definitions.
       time [string]

       Uses  the  message  line to display the time of day, the host name, and the load averages over 1, 5, and 15 minutes (if this is available on your system).
       For window specific information use “info”.

       If a string is specified, it changes the format of the time report like it is described in the “STRING ESCAPES” chapter. Screen uses a default  of  “%c:%s
       %M %d %H%? %l%?”.

       title [windowtitle]

       Set  the name of the current window to windowtitle. If no name is specified, screen prompts for one. This command was known as ‘aka’ in previous releases.

       unsetenv var

       Unset an environment variable.

       utf8 [on|off [on|off]]

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

       vbell [on|off]

       Sets the visual bell setting for this window. Omitting the parameter toggles the setting. If vbell is switched on, but your terminal does  not  support  a
       visual  bell, a ‘vbell-message’ is displayed in the status line when the bell character (^G) is received.  Visual bell support of a terminal is defined by
       the termcap variable ‘vb’ (terminfo: ‘flash’).
       Per default, vbell is off, thus the audible bell is used.  See also ‘bell_msg’.

       vbell_msg [message]

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

       vbellwait sec

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

       verbose [on|off]

       If  verbose  is switched on, the command name is echoed, whenever a window is created (or resurrected from zombie state). Default is off.  Without parame-
       ter, the current setting is shown.

       version

       Print the current version and the compile date in the status line.

       wall message

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

       width [-w|-d] [cols [lines]]

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

       windowlist [-b] [-m]
       windowlist string [string]
       windowlist title [title]

       Display all windows in a table for visual window selection. The desired window can be selected via the standard movement keys (see the “copy” command) and
       activated via the return key.  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 table format can be changed with the string and title option, the title is displayed as table heading, while the lines are made by  using  the  string
       setting.  The  default  setting  is “Num Name%=Flags” for the title and “%3n %t%=%f” for the lines.  See the “STRING ESCAPES” chapter for more codes (e.g.
       color settings).

       windows

       Uses the message line to display a list of all the windows.  Each window is listed by number with the name of process that has been started in the  window
       (or  its title); the current window is marked with a ‘*’; the previous window is marked with a ‘-’; all the windows that are “logged in” are marked with a
       ‘$’; a background window that has received a bell is marked with a ‘!’; a background window that is being monitored and has had activity occur  is  marked
       with  an ‘@’; a window which has output logging turned on is marked with ‘(L)’; windows occupied by other users are marked with ‘&’; windows in the zombie
       state are marked with ‘Z’.  If this list is too long to fit on the terminal’s status line only the portion around the current window is displayed.

       wrap [on|off]

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

       writebuf [-e encoding] [filename]

       Writes the contents of the paste buffer to the specified file, or the public accessible screen-exchange file if no filename is given. This is  thought  of
       as  a  primitive means of communication between screen users on the same host. If an encoding is specified the paste buffer is recoded on the fly to match
       the encoding.  The filename can be set with the bufferfile command and defaults to “/tmp/screen-exchange”.

       writelock [on|off|auto]

       In addition to access control lists, not all users may be able to write to the same window at once. Per default, writelock is in ‘auto’  mode  and  grants
       exclusive  input  permission to the user who is the first to switch to the particular window. When he leaves the window, other users may obtain the write-
       lock (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.

       xoff
       xon

       Insert a CTRL-s / CTRL-q character to the stdin queue of the current window.

       zmodem [off|auto|catch|pass]
       zmodem sendcmd [string]
       zmodem recvcmd [string]

       Define  zmodem  support  for  screen.  Screen understands two different modes when it detects a zmodem request: “pass” and “catch”.  If the mode is set to
       “pass”, screen will relay all data to the attacher until the end of the transmission is reached.  In “catch” mode screen acts as  a  zmodem  endpoint  and
       starts  the  corresponding rz/sz commands. If the mode is set to “auto”, screen will use “catch” if the window is a tty (e.g. a serial line), otherwise it
       will use “pass”.
       You can define the templates screen uses in “catch” mode via the second and the third form.
       Note also that this is an experimental feature.

       zombie [keys]
       defzombie [keys]

       Per default screen windows are removed from the window list as soon as the windows process (e.g. shell) exits. When a string of two keys is  specified  to
       the zombie command, ‘dead’ windows will remain in the list.  The kill command may be used to remove such a window. Pressing the first key in the dead win-
       dow has the same effect. When pressing the second key, screen will attempt to resurrect the window. The process that was initially running in  the  window
       will be launched again. Calling zombie without parameters will clear the zombie setting, thus making windows disappear when their process exits.

       As  the  zombie-setting is manipulated globally for all windows, this command should only be called defzombie. Until we need this as a per window setting,
       the commands zombie and defzombie are synonymous.

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

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

              echo ‘<esc>^Hello world from window ‘$WINDOW’<esc>\\’

       where ‘<esc>’ is an escape, ‘^’ is a literal up-arrow, and ‘\\’ turns into a single backslash.

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

       ?  The normal window contains a shell (default, if no parameter is given) or any other system command that could be executed from a shell  (e.g.   slogin,
          etc…)

       ?  If  a tty (character special device) name (e.g. “/dev/ttya”) is specified as the first parameter, then the window is directly connected to this device.
          This window type is similar to “screen cu -l /dev/ttya”.  Read and write access is required on the device node, an exclusive open is attempted  on  the
          node  to  mark  the  connection  line  as busy.  An optional parameter is allowed consisting of a comma separated list of flags in the notation used by
          stty(1):

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

          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 -ixon
                 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 dependant and may be in defaults or values saved from a previous connection.

          For  tty  windows,  the  info  command shows some of the modem control lines in the status line. These may include ‘RTS’, ‘CTS’, ‘DTR’, ‘DSR’, ‘CD’ and
          more.  This depends on the available ioctl()’s and system header files as well as the on the physical capabilities of the serial board.   Signals  that
          are  logical  low (inactive) have their name preceded by an exclamation mark (!), otherwise the signal is logical high (active).  Signals not supported
          by the hardware but available to the ioctl() interface are usually shown low.
          When the CLOCAL status bit is true, the whole set of modem signals is placed inside curly braces ({ and }).  When the CRTSCTS  or  TIOCSOFTCAR  bit  is
          set, the signals ‘CTS’ or ‘CD’ are shown in parenthesis, 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 com-
                 mand ‘term’).

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

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

          Additional flags for debugging are x, t and n (XDISPLOC, TSPEED and NEWENV).

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

          This window type is only available if screen was compiled with the BUILTIN_TELNET option defined.

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

       Here is the full list of supported escapes:

       %      the escape character itself

       a      either ‘am’ or ‘pm’

       A      either ‘AM’ or ‘PM’

       c      current time HH:MM in 24h format

       C      current time HH:MM in 12h format

       d      day number

       D      weekday name

       f      flags of the window

       F      sets %? to true if the window has the focus

       h      hardstatus of the window

       H      hostname of the system

       l      current load of the system

       m      month number

       M      month name

       n      window number

       s      seconds

       t      window title

       u      all other users on this window

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

       W      all window numbers and names except the current one

       y      last two digits of the year number

       Y      full year number

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

       :      else part of ‘%?’

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

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

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

       {      attribute/color modifier string terminated by the next “}”

       ‘      Substitute with the output of a ‘backtick’ command. The length qualifier is misused to identify one of the commands.

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

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

       +      add the specified set to the current attributes

       -      remove the set from the current attributes

       !      invert the set in the current attributes

       =      change the current attributes to the specified set

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

       d      dim
       u      underline
       b      bold
       r      reverse
       s      standout
       B      blinking

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

       k      black
       r      red
       g      green
       y      yellow
       b      blue
       m      magenta
       c      cyan
       w      white
       d      default color
       .      leave color unchanged

       The capitalized versions of the letter specify bright colors. You can also use the pseudo-color ‘i’ to  set  just  the  brightness  and  leave  the  color
       unchanged.
       A  one  digit/letter color description is treated as foreground or background color dependant on the current attributes: if reverse mode is set, the back-
       ground color is changed instead of the foreground color.  If you don’t like this, prefix the color with a “.”. If you want the same behaviour for two-let-
       ter color descriptions, also prefix them with a “.”.
       As  a  special  case,  “%{-}”  restores  the  attributes and colors that were set before the last change was made (i.e. pops one level of the color-change
       stack).

       Examples:

       “G”    set color to bright green

       “+b r” use bold red

       “= yd” clear all attributes, write in default color on yellow background.

       %-Lw%{= BW}%50>%n%f* %t%{-}%+Lw%<
              The available windows centered at the current window and truncated to the available width. The current window is displayed white on blue.  This can
              be used with “hardstatus alwayslastline”.

       %?%F%{.R.}%?%3n %t%? [%h]%?
              The window number and title and the window’s hardstatus, if one is set.  Also use a red background if this is the active focus. Useful for “caption
              string”.

FLOW-CONTROL
       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” .screenrc command. Per default the windows are set to auto-
       matic flow-switching.  It can then be toggled between the three states ‘fixed on’, ‘fixed off’ and ‘automatic’ interactively with the “flow” command bound
       to “C-a f”.

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

       If  you’re running with flow-control enabled and find that pressing the interrupt key (usually C-c) does not interrupt the display until another 6-8 lines
       have scrolled by, try running screen with the “interrupt” option (add the “interrupt” flag to the “flow” command in your .screenrc, or use the -i command-
       line option).  This causes the output that screen has accumulated from the interrupted program to be flushed.  One disadvantage is that the virtual termi-
       nal’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  it is possible to interrupt the output of the virtual terminal to your physical terminal when flow-control is enabled.  If this
       happens, a simple refresh of the screen with “C-a l” will restore it.  Give each mode a try, and use whichever mode you find more comfortable.

TITLES (naming windows)
       You can customize each window’s name in the window display (viewed with the “windows” command (C-a w)) by setting it with one of the title commands.  Nor-
       mally the name displayed is the actual command name of the program created in the window.  However, it is sometimes useful to distinguish various programs
       of the same name or to change the name on-the-fly to reflect the current state of the window.

       The default name for all shell windows can be set with the “shelltitle” command in the .screenrc file, while all other windows are created with a “screen”
       command  and thus can have their name set with the -t option.  Interactively, there is the title-string escape-sequence (<esc>kname<esc>\) and the “title”
       command (C-a A).  The former can be output from an application to control the window’s name under software control, and the latter will prompt for a  name
       when typed.  You can also bind pre-defined names to keys with the “title” command to set things quickly without prompting.

       Finally,  screen  has  a shell-specific heuristic that is enabled by setting the window’s name to “search|name” and arranging to have a null title escape-
       sequence output as a part of your prompt.  The search portion 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 win-
       dow’s shell name (e.g. “name:cmd”).  Otherwise the current command name supersedes the shell name while it is running.

       Here’s how it works:  you must modify your shell prompt to output a null title-escape-sequence (<esc>k<esc>\) as a part of your prompt.  The last part  of
       your  prompt  must  be  the  same as the string you specified for the search portion of the title.  Once this is set up, screen will use the title-escape-
       sequence to clear the 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 either
       ‘!’, ‘%’, 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  better
       command names when using job control or history recall commands.

       Here’s some .screenrc examples:

              screen -t top 2 nice top

       Adding this line to your .screenrc would start a nice-d version of the “top” command in window 2 named “top” rather than “nice”.

                   shelltitle ‘> |csh’
                   screen 1

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

              /usr/joe/src/dir> trn

       (it looks after the ‘> ‘ for the command name).  The window status would show the name “trn” while the command was running, and revert to “csh” upon  com-
       pletion.

              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-title’s
       current setting (C-a E).  The third binding would set the current window’s title to “(unknown)” (C-a u).

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

              set prompt=’^[[0000m^[k^[\% '

       The escape-sequence "<esc>[0000m" not only normalizes the character attributes, but all the zeros round the length of the invisible characters  up  to  8.
       Bash users will probably want to echo the escape sequence in the PROMPT_COMMAND:

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

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

THE VIRTUAL TERMINAL
       Each  window in a screen session emulates a VT100 terminal, with some extra functions added. The VT100 emulator is hard-coded, no other terminal types can
       be emulated.
       Usually screen tries to emulate as much of the VT100/ANSI standard as possible. But if your terminal lacks certain capabilities, the emulation may not  be
       complete.  In these cases screen has to tell the applications that some of the features are missing. This is no problem on machines using termcap, because
       screen can use the $TERMCAP variable to customize the standard screen termcap.

       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 $TERM-
       CAP variable reflecting the capabilities of the virtual terminal emulated. Notice that, however, on machines using the terminfo database this variable has
       no effect.  Furthermore, the variable $WINDOW is set to the window number of each window.

       The  actual  set  of capabilities supported by the virtual terminal depends on the capabilities supported by the physical terminal.  If, for instance, the
       physical terminal does not support underscore mode, screen does not put the 'us' and 'ue' capabilities into the window's $TERMCAP  variable,  accordingly.
       However,  a  minimum  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" .screenrc command, or  by  defining  the  variable  $SCREENCAP  prior  to
       startup.   When the is latter defined, its value will be copied verbatim into each window's $TERMCAP variable.  This can either be the full terminal defi-
       nition, or a filename where the terminal "screen" (and/or "screen-w") is defined.

       Note that screen honors the "terminfo" .screenrc command if the system uses the terminfo database rather than termcap.

       When the boolean 'G0' capability is present in the termcap entry for the terminal on which screen has been called, the terminal emulation of  screen  sup-
       ports 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 win-
       dows are still active (the printer port is enabled and disabled again for each chunk of output).  As a side-effect, programs running in different  windows
       can send output to the printer simultaneously.  Data sent to the printer is not displayed in the window.  The info command displays a line starting 'PRIN'
       while the printer is active.

       Screen maintains a hardstatus line for every window. If a window gets selected, the display's hardstatus will be updated to match the window's  hardstatus
       line. If the display has no hardstatus the line will be displayed as a standard screen message.  The hardstatus line can be changed with the ANSI Applica-
       tion Program Command (APC): "ESC_<string>ESC\". As a convenience for xterm users the sequence "ESC]0..2;<string>^G” is also accepted.

       Some capabilities are only put into the $TERMCAP variable of the virtual terminal if they can be efficiently implemented by the  physical  terminal.   For
       instance,  ‘dl’  (delete  line)  is only put into the $TERMCAP variable if the terminal supports either delete line itself or scrolling regions. Note that
       this may provoke confusion, when the session is reattached on a different terminal, as the value of $TERMCAP cannot be modified by parent processes.
       The “alternate screen” capability is not enabled by default.  Set the altscreen .screenrc command to enable it.

       The following is a list of control sequences recognized by screen.  “(V)” and “(A)” indicate VT100-specific and ANSI- or ISO-specific  functions,  respec-
       tively.

       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                      A.k.a. Definition String

       ESC P                 (A)  Device Control String.  Outputs a string directly to the host terminal without interpretation.

       ESC _                 (A)  Application Program Command (Hardstatus)

       ESC ] 0 ; string ^G   (A)  Operating System Command (Hardstatus, xterm title hack)

       ESC ] 83 ; cmd ^G     (A)  Execute  screen  command.  This only works if multi-user support is compiled into screen. The pseudo-user “:window:” is used to
                                  check the access control list. Use “addacl :window: -rwx #?” to create a user with no rights and allow  only  the  needed  com-
                                  mands.

       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                    Send Terminal Parameter Report

       ESC [ > c                  Send VT220 Secondary Device Attributes String

       ESC [ 6 n                  Send Cursor Position Report

INPUT TRANSLATION
       In  order  to  do  a full VT100 emulation screen has to detect that a sequence of characters in the input stream was generated by a keypress on the user's
       keyboard and insert the VT100 style escape sequence. Screen has a very flexible way of doing this by making it possible to map arbitrary commands on arbi-
       trary  sequences  of  characters. For standard VT100 emulation the command will always insert a string in the input buffer of the window (see also command
       stuff in the command table).  Because the sequences generated by a keypress can change after a reattach from a different terminal type, it is possible  to
       bind commands to the termcap name of the keys.  Screen will insert the correct binding after each reattach. See the bindkey command for further details on
       the syntax and examples.

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

       Key name          Termcap name    Command
       ______________________________________________________
       Cursor up             ku          stuff \033[A
                                         stuff \033OA    (A)
       Cursor down           kd          stuff \033[B
                                         stuff \033OB    (A)
       Cursor right          kr          stuff \033[C
                                         stuff \033OC    (A)
       Cursor left           kl          stuff \033[D
                                         stuff \033OD    (A)
       Function key 0        k0          stuff \033[10~
       Function key 1        k1          stuff \033OP
       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)

SPECIAL TERMINAL CAPABILITIES
       The following table describes all terminal capabilities that are recognized by screen and are not in the termcap(5) manual.  You can place these capabili-
       ties in your termcap entries (in '/etc/termcap') or use them with the commands 'termcap', 'terminfo' and 'termcapinfo' in your screenrc files. It is often
       not possible to place these capabilities in the terminfo database.

       LP   (bool)  Terminal has VT100 style margins ('magic margins'). Note that this capability is obsolete because screen uses the standard 'xn' instead.

       Z0   (str)   Change width to 132 columns.

       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 back to normal mode.

       AN   (bool)  Turn on autonuke. See the 'autonuke' command for more details.

       OL   (num)   Set the output buffer limit. See the 'obuflimit' command for more details.

       KJ   (str)   Set the encoding of the terminal. See the 'encoding' command for valid encodings.

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

       AB   (str)   Same as 'AF', but change background color.

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

       XC   (str)   Describe a translation of characters to strings depending on the current font. More details follow in the next section.

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

       C8   (bool)  Terminal needs bold to display high-intensity colors (e.g. Eterm).

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

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

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

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

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

       Here is an example:

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

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

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

       This example shows one use of the extension:

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

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

ENVIRONMENT
       COLUMNS        Number of columns on the terminal (overrides termcap entry).
       HOME           Directory in which to look for .screenrc.
       LINES          Number of lines on the terminal (overrides termcap entry).
       LOCKPRG        Screen lock program.
       NETHACKOPTIONS Turns on nethack option.
       PATH           Used for locating programs to run.
       SCREENCAP      For customizing a terminal’s TERMCAP value.
       SCREENDIR      Alternate socket directory.
       SCREENRC       Alternate user screenrc file.
       SHELL          Default shell program for opening windows (default “/bin/sh”).
       STY            Alternate socket name.
       SYSSCREENRC    Alternate system screenrc file.
       TERM           Terminal name.
       TERMCAP        Terminal description.
       WINDOW         Window number of a window (at creation time).

FILES
       …/screen-4.?.??/etc/screenrc
       …/screen-4.?.??/etc/etcscreenrc Examples in the screen distribution package for private and global initialization files.
       $SYSSCREENRC
       /etc/screenrc                     screen initialization commands
       $SCREENRC
       $HOME/.screenrc                   Read in after /etc/screenrc
       $SCREENDIR/S-<login>
       /local/screens/S-<login>          Socket directories (default)
       /usr/tmp/screens/S-<login>        Alternate socket directories.
       <socket directory>/.termcap       Written by the “termcap” output function
       /usr/tmp/screens/screen-exchange  or
       /tmp/screen-exchange              screen ‘interprocess communication buffer’
       hardcopy.[0-9]                    Screen images created by the hardcopy function
       screenlog.[0-9]                   Output log files created by the log function
       /usr/lib/terminfo/?/*             or
       /etc/termcap                      Terminal capability databases
       /etc/utmp                         Login records
       $LOCKPRG                          Program that locks a terminal.

SEE ALSO
       termcap(5), utmp(5), vi(1), captoinfo(1), tic(1)

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

COPYLEFT
       Copyright (C) 1993-2003
            Juergen Weigert (jnweiger@immd4.informatik.uni-erlangen.de)
            Michael Schroeder (mlschroe@immd4.informatik.uni-erlangen.de)
       Copyright (C) 1987 Oliver Laumann
       This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the  Free  Soft-
       ware Foundation; either version 2, or (at your option) any later version.
       This  program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
       FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
       You should have received a copy of the GNU General Public License along with this program (see the file COPYING); if not, write to the Free Software Foun-
       dation, Inc., 59 Temple Place – Suite 330, Boston, MA  02111-1307, USA

CONTRIBUTORS
       Ken Beal (kbeal@amber.ssd.csd.harris.com),
       Rudolf Koenig (rfkoenig@immd4.informatik.uni-erlangen.de),
       Toerless Eckert (eckert@immd4.informatik.uni-erlangen.de),
       Wayne Davison (davison@borland.com),
       Patrick Wolfe (pat@kai.com, kailand!pat),
       Bart Schaefer (schaefer@cse.ogi.edu),
       Nathan Glasser (nathan@brokaw.lcs.mit.edu),
       Larry W. Virden (lvirden@cas.org),
       Howard Chu (hyc@hanauma.jpl.nasa.gov),
       Tim MacKenzie (tym@dibbler.cs.monash.edu.au),
       Markku Jarvinen (mta@{cc,cs,ee}.tut.fi),
       Marc Boucher (marc@CAM.ORG),
       Doug Siebert (dsiebert@isca.uiowa.edu),
       Ken Stillson (stillson@tsfsrv.mitre.org),
       Ian Frechett (frechett@spot.Colorado.EDU),
       Brian Koehmstedt (bpk@gnu.ai.mit.edu),
       Don Smith (djs6015@ultb.isc.rit.edu),
       Frank van der Linden (vdlinden@fwi.uva.nl),
       Martin Schweikert (schweik@cpp.ob.open.de),
       David Vrona (dave@sashimi.lcu.com),
       E. Tye McQueen (tye%spillman.UUCP@uunet.uu.net),
       Matthew Green (mrg@eterna.com.au),
       Christopher Williams (cgw@pobox.com),
       Matt Mosley (mattm@access.digex.net),
       Gregory Neil Shapiro (gshapiro@wpi.WPI.EDU),
       Johannes Zellner (johannes@zellner.org),
       Pablo Averbuj (pablo@averbuj.com).

VERSION
       This  is  version  4.0.2. Its roots are a merge of a custom version 2.3PR7 by Wayne Davison and several enhancements to Oliver Laumann’s version 2.0. Note
       that all versions numbered 2.x are copyright by Oliver Laumann.

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

BUGS
       ?  ‘dm’ (delete mode) and ‘xs’ are not handled correctly (they are ignored). ‘xn’ is treated as a magic-margin indicator.

       ?  Screen has no clue about double-high or double-wide characters.  But this is the only area where vttest is allowed to fail.

       ?  It is not possible to change the environment variable $TERMCAP when reattaching under a different terminal type.

       ?  The support of terminfo based systems is very limited. Adding extra capabilities to $TERMCAP may not have any effects.

       ?  Screen does not make use of hardware tabs.

       ?  Screen must be installed as set-uid with owner root on most systems in order to be able to correctly change the owner of the tty device file  for  each
          window.  Special permission may also be required to write the file “/etc/utmp”.

       ?  Entries in “/etc/utmp” are not removed when screen is killed with SIGKILL.  This will cause some programs (like “w” or “rwho”) to advertise that a user
          is logged on who really isn’t.

       ?  Screen may give a strange warning when your tty has no utmp entry.

       ?  When the modem line was hung up, screen may not automatically detach (or quit) unless the device driver is configured to  send  a  HANGUP  signal.   To
          detach a screen session use the -D or -d command line option.

       ?  If a password is set, the command line options -d and -D still detach a session without asking.

       ?  Both “breaktype” and “defbreaktype” change the break generating method used by all terminal devices. The first should change a window specific setting,
          where the latter should change only the default for new windows.

       ?  When attaching to a multiuser session, the user’s .screenrc file is not sourced. Each user’s personal settings have to be  included  in  the  .screenrc
          file from which the session is booted, or have to be changed manually.

       ?  A weird imagination is most useful to gain full advantage of all the features.

       ?  Send bug-reports, fixes, enhancements, t-shirts, money, beer & pizza to screen@uni-erlangen.de.

4th Berkeley Distribution          Aug 2003                          SCREEN(1)