The name of this program was changed to iScreen to be able to distinguish it from Oliver Laumann's original screen program. Despite that fact, this manual will continue to use the name screen. This is, because often the binary is installed as 'screen'.
When screen is called, it creates a single window with a shell in it (or the specified command) and then gets out of your way so that you can use the program as you normally would. Then, at any time, you can create new (full-screen) windows with other programs in them (including more shells), kill existing windows, view a list of the current windows, turn output logging on and off, copy-and-paste text between windows, view the scrollback history, switch between windows in whatever manner you wish, etc. When a program terminates, screen 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 command to the window manager. By default, each command begins with a control-a (abbreviated C-a from now on), and is followed by one other keystroke. The command character and all the key bindings can be fully customized to be anything you like, though they are always two characters in length.
The standard way to create a new window is to type "C-a c". This creates a new window running a shell and switches to that window immediately, regardless of the state of the process running in the current window. Similarly, you can create a new window with a custom command in it by first binding the command to a keystroke (in your .screenrc file) and then using it just like the "C-a c" command. In addition, new windows can be created by running a command like:
from a shell prompt within a previously created window. This will not run another copy of screen, but will instead supply the command name and its arguments to the window manager 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 terminals own record is removed from the utmp file. See also "C-a L".
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 "COMMAND KEYS". The manual section "CUSTOMIZATION" deals with the contents of your .screenrc.
If possible, choose 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. The next best thing is an auto-margin terminal that allows the last position on the screen to be updated without scrolling the screen (such as a vt100). This also allows the entire screen to be updated. Lastly, 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.
If your terminal is of the second type (firm-margined `am'), you will want to let screen know about this, since a normal termcap doesn't distinguish this type of automatic margins from a "true" `am' terminal. You do this by specifying the `LP' capability in your termcap (see the "termcap" .screenrc command), or by using the -L command-line option. Screen needs this information to correctly update the screen.
If you are using a "true" auto-margin terminal (no `LP') at low baud rates, you may want to turn on a more optimal output mode by including the flag `OP' in your termcap entry, or by specifying the -O command-line option. The trade-off is that screen will no-longer accurately emulate the vt100's line-end quirks (e.g. the screen will scroll after putting one character in the last screen position).
The following keystroke commands are available:
When screen is invoked, it executes initialization commands from the files "/local/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 $SYSSCREENRC. The user specific screenrc file is searchend in $ISCREENRC, then $SCREENRC, then $HOME/.iscreenrc and finally defaults to $HOME/.screenrc. The command line option -c takes precedence over the user specific screenrc file. Commands in these files are used to set options, bind functions to keys, and to automatically establish one or more extra windows at the beginning of your screen session. Commands are listed one per line, with empty lines being ignored. A command's arguments are separated by tabs or spaces, and may be surrounded by single or double quotes. A `#' turns the rest of the line into a comment, except in quotes. Unintelligible lines are warned about and ignored. Commands may contain references to environment variables. The syntax is the shell-like "$VAR " or "${VAR}". Note that this causes incompatibilities with previous screen versions, as now the '$'-sign has to be protected with '' if no variable substitution shall be performed.
Customization can also be done 'on-line'. To enter the command mode type `C-a :'. Setting flags (like scrollback, login, etc.) on-line may not have the desired effect, as e.g. the command "C-a : login on" will affect only the settings for the creation of new windows (just like within .screenrc). If you intend to change flags of the current window, then prepend the command with the keyword "set". E.g. "C-a : set login on" will log this window in.
The following initialization commands are available:
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 `~' is replaced by the definition for bell in your termcap (usually an audible bell). The default message is
'Activity in window %'
Note that monitoring is off for all windows by default, but can be altered by use of the "monitor" command (C-a M).
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.
bell message
When a bell character is sent to a background window, screen displays a notification in the message line. The notification message can be re-defined by means of the "bell" command. Each occurrence of `%' in message is replaced by the number of the window to which a bell has been sent, and each occurrence of `~' is replaced by the definition for bell in your termcap (usually an audible bell). The default message is
'Bell in window %'
An empty message can be supplied to the "bell" command to suppress output of a message line (bell "").
bind key [function [args]]
Bind a function to a key. By default, each function provided by screen is bound to one or more keys as indicated by the above table, e.g. the function 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 number (specifying the ASCII code of the character), or a backslash followed by a second character, such as "\^" or "\\". The argument can also be quoted, if you like. If no further argument is given, any previously established binding for this key is removed. The function argument can be one of the following keywords:
select0 Switch to window #0 ... select9 Switch to window #9 aka Change the current window's a.k.a. clear Clear the screen colon Enter one ".screenrc" command on-the-fly. copy Select a piece of text. detach Detach screen flow Toggle the current window's flow-control setting hardcopy Make hardcopy of current window history Use cut&paste to fetch a recently displayed line. help Display a list of the key bindings in effect info Display the current window's status information kill Kill the current window lastmsg Redisplay the last message line lock Run a screenlock program. log Begin/end logging of the current window's output login Toggle the window's "login" setting (/etc/utmp entry) monitor Toggle activity monitoring of the current window next Switch to the next window other Switch to the window displayed previously paste Paste in a selected piece of text. pow_detach Detach screen and logout. prev Switch to the previous window quit Kill all windows and terminate readbuffer Take text from the exchange file. redisplay Redisplay current window reset Reset the window to its "power-on" settings screen Create a new window with the specified command shell Create a new window with a shell suspend Suspend screen termcap Write screen's termcap entry to $HOME/.screencap vbell Toggle the window's "vbell" setting. version Display the version numbers and date last modified width Toggle the terminal width between 80 and 132 columns windows Display a list of all windows wrap Toggle the current window's line-wrap setting writebuffer Store the selected text in the exchange file. xoff Send a control-s to the current program xon Send a control-q to the current program
Some examples:
bind ' ' windows bind ^f screen telnet foobar bind \033 screen -ln -t root -h 1000 9 su
would bind the space key to the function that displays a list of windows (so that the function usually invoked by "C-a C-w" would also be available as "C-a space"), bind "C-f" to the function "create a window with a TELNET connection to foobar", and bind "escape" to the function that creates an non-login window with a.k.a. "root" in slot #9, with a super-user shell and a scrollbackbuffer of 1000 lines.
bufferfile exchange-file
Change the filename used for reading and writing with the copybuffer. The default is "/tmp/screen-exchange". The following example will paste the system's password file into the screen window:
C-a : bufferfile /etc/passwd C-a < C-a ]
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.
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 only `LF' is used.
echo [-n] message
The echo command may be used to annoy screen users with a 'message of the day'. Typically installed in a global /local/etc/screenrc. See also "sleep". Echo is also useful for online checking of environment variables.
escape xy
Set the command character to x and the character generating a literal command character to y (just like in the -e option). Each argument is either a single character, a two-character sequence of the form "^x" (meaning "C-x"), a backslash followed by an octal number (specifying the ASCII code of the character), or a backslash followed by a second character, such as "\^" or "\\". The default is "^Aa", but "``" is recommended by one of the authors.
flow on|off|auto [interrupt]
Sets the default flow-control mode for new windows. Specifying "flow auto interrupt" is the same as the command-line options -fa and -i. 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.
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.
hardstatus on|off
Toggles the use of the terminals hardware status line. If "on", screen will use this facility to display one line messages. Otherwise these messages are overlayed in reverse video mode at the display line. Note that the hardstatus feature should only be used, if the termcap/terminfo capabilities "hs", "ts", "fs" and "ds" are set properly.
login on|off
Sets the login flag which determines if new windows should have /etc/utmp entries added for them. The login state is also changeable on-the-fly by using the bindable version of the "login" command (C-a L) of by means of "C-a : set login on|off". The default should be "on" for a screen that runs under suid-root.
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' from their (original emacs-style bindings) to the vi style binding (scroll up/down full page), which is the default meaning of `B' and `F'.
mode mode
The mode of each newly allocated pseudo-tty is set to mode. Mode is an octal number. When no "mode" command is given, mode 0622 is used.
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 activity 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. Monitoring is initially off for all windows.
msgminwait sec
Defines the time screen delays all activity after a message was dispayled. 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.
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 environment
variable $NETHACKOPTIONS.
password [crypted_pw]
Present a crypted password in your ".screenrc" file and screen will ask for it, whenever a detached session is tried to be resumed. This is useful, if you have privileged programs running under screen and you want to protect your session from reattach attempts by users that managed to have your uid. (I.e. any superuser.)
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.
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>) and scrollback option (-h <num>) may be specified for each command. If an optional number n in the range 0..9 is given, the window number n is assigned to the newly created window (or, if this number is already in-use, the next available number). If a command is specified after "screen", this command (with the given arguments) is started in the window; otherwise, a shell is created. Thus, if your ".screenrc" contains the lines
# example for .screenrc: screen 1 screen -fn -t foobar 2 telnet foobar
screen creates a shell window (in window #1) and a window with a TELNET connection to the machine foobar (with no flow-control using the a.k.a. "foobar" in window #2). If you do not include any screen commands in your ".screenrc" file, then screen defaults to creating a single shell window, number zero. When the initialization is completed, screen switches to the last window specified in your .screenrc file or, if none, it opens default window #0.
scrollback num
Set the size of the scrollback buffer for new windows to num lines. The default scrollback is 50 lines. Use "C-a : set scrollback num" to change the scrollback size of the current window and use "C-a i" to view the current setting.
redraw on|off
Define whether the display should be refreshed (as done with "C-a l") after switching to the current window. As usual when the "set" keyword is given, this command only affects the current window. But unlike other commands, "redraw off" (without "set") affects all windows, the window specific settings come into effect again when "redraw on" (without "set") is entered.
shell command
Set the command to be used to create a new shell. This overrides the value of the environment variable $SHELL, or "/bin/sh" if undefined. This is useful if you'd like to run a tty-enhancer which is expecting to execute the program specified in $SHELL.
shellaka a.k.a.
Set the a.k.a. for all shells created during startup or by the C-A C-c command. For details about what a.k.a.'s are, see the discussion entitled ALSO KNOWN AS.
sleep num This command will pause the execution of a .screenrc file for num seconds. It may be used to give users a chance to read the messages output by "echo".
slowpaste usec
Define the speed text is inserted by the paste ("C-a ]") command. For each 80 characters (IOSIZE) pasted screen will make a pause of usec milliseconds to allow the application the processing of input. Use that, if you have to fear that your underlying system chokes on large pastes.
startup_message on|off
Select whether to display the copyright notice when screen starts up.
term term
In each window's environment screen opens, it sets the $TERM variable to "screen" by default, unless no description for "screen" is installed in the local termcap or terminfo data base. In that case it pretends that the terminal emulator is "vt100". This won't do much harm, as screen is VT100/ANSI compatible. The use of the "term" command is discouraged for non-default purpose. That is, one may want to specify special $TERM settings (e.g. vt100) for the next "screen rlogin othermachine" command. Use the command "screen -T vt100 rlogin othermachine" rather than setting ("term vt100") and resetting ("term screen") the default before and after the "screen" command.
termcap term terminal-tweaks [window-tweaks]
terminfo 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. If your system works with terminfo-database rather than with termcap screen will understand the `terminfo' command which has the same effects as the `termcap' command. Thus users can write one .screenrc file that handles both cases, although terminfo syntax is slightly different from termcap syntax.
The first argument specifies which terminal(s) should be affected by this definition. You can specify multiple terminal names by separating them with `|'s. Use `*' to match all terminals and `vt*' to match all terminals that begin with "vt".
Each tweak argument contains one or more termcap defines (separated by `:'s) to be inserted at the start of the appropriate termcap entry, enhancing it or overriding existing values. The first tweak modifies your terminal's termcap, and contains definitions that your terminal uses to perform certain functions. Specify a null string to leave this unchanged (e.g. ''). The second (optional) tweak modifies all the window termcaps, and should contain definitions that screen understands (see the "VIRTUAL TERMINAL" section).
Some examples:
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.)
This leaves your vt100 termcap alone and adds the function key labels to each window's termcap entry.
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 discussion on the "VIRTUAL TERMINAL" in this manual, and the termcap(5) man page for more information on termcap definitions.
vbell on|off
Sets the visual bell setting for new windows. If your terminal does not support a visual bell a message is printed to the status line. The default message is "Wuff, Wuff!!".
vbell_msg message
Sets the visual bell message. message is printed to the status line if the window receives a bell character (^G) and vbell is set to "on".
vbellwait sec
Define a delay in seconds after each display of screen 's visual bell message. The default is 0 seconds.
wrap on|off
Sets the line-wrap setting for new windows. 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. Line-wrap is on by default and can be toggled with the "wrap" command ("C-a r") or by means of "C-a : set wrap on|off".
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:
where '<esc>' is an escape, '^' is a literal up-arrow, and '\\' turns into a single backslash.
Each window has an initial flow-control value set with either the -f option or the "flow" .screenrc command. Per default the windows are set to automatic flow-switching. It can then be toggled between the three states 'fixed on', 'fixed off' and
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 terminal's memory contains the non-flushed version of the output, which in rare cases can cause minor inaccuracies in the output. For example, if you switch screens and return, or update the screen with "C-a l" you would see the version of the output you would have gotten without "interrupt" being on. Also, you might need to turn off flow-control (or use auto-flow mode to turn it off automatically) when running a program that expects you to type the interrupt character as input, as 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.
The default name for all shell windows can be set with the "shellaka" 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 AKA-string escape-sequence (<esc>kname<esc>\) and the "aka" 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 "aka" 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 aka 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 window'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 aka 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 a.k.a. Once this is set up, screen will use the aka 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:
Adding this line to your .screenrc would start a niced version of the "top" command in window 2 name "top" rather than "nice".
shellaka '> |csh' screen 1
This file would start a shell using the given shellaka. The a.k.a. specified is an auto-aka that would expect the prompt and the typed command to look something like the following:
(it looks after the '> ' for the command name). The window status would show the name "trn" while the command was running, and revert to "csh" upon completion.
Having this command in your .screenrc would bind the key sequence "C-a R" to the "su" command and give it an auto-aka name of "root:". For this auto-aka 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 aka bind E aka "" bind u aka (unknown)
The first binding doesn't have any arguments, so it would prompt you for an a.k.a. when you type "C-a o". The second binding would clear an auto-aka's current setting (C-a E). The third binding would set the current window's a.k.a. to "(unknown)" (C-a u).
One thing to keep in mind when adding a null aka 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:
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:
(I used "134" to output a `\' because of a bug in v1.04).
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 latter defined, its value will be copied verbatim into each window's $TERMCAP variable. This can either be the full terminal definition, or a filename where the terminal "screen" (and/or "screen-w") is defined.
Note that screen honors the "terminfo" .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 supports multiple character sets. This allows an application to make use of, for instance, the VT100 graphics character set or national character sets. The following control functions from ISO 2022 are supported: lock shift G0 (SI), lock shift G1 (SO), lock shift G2, lock shift G3, single shift G2, and single shift G3. When a virtual terminal is created or reset, the ASCII character set is designated as G0 through G3. When the `G0' capability is present, screen evaluates the capabilities `S0', `E0', and `C0' if present. `S0' is the sequence the terminal uses to enable and start the graphics character set rather than SI. `E0' is the corresponding replacement for SO. `C0' gives a character by character translation string that is used during semi-graphics mode. This string is built like the `acsc' terminfo capability.
When the `po' and `pf' capabilities are present in the terminal's termcap entry, applications running in a screen window can send output to the printer port of the terminal. This allows a user to have an application in one window sending output to a printer connected to the terminal, while all other windows are still active (the printer port is enabled and disabled again for each chunk of output). As a side-effect, programs running in different windows can send output to the printer simultaneously. Data sent to the printer is not displayed in the window.
Some capabilities are only put into the $TERMCAP variable of the virtual terminal if they can be efficiently implemented by the physical terminal. For instance, `dl' (delete line) is only put into the $TERMCAP variable if the terminal supports either delete line itself or scrolling regions. Note that this may provoke confusion, when the session is reattached on a different terminal, as the value of $TERMCAP cannot be modified by parent processes.
The following is a list of control sequences recognized by screen. "(V)" and "(A)" indicate VT100-specific and ANSI- or ISO-specific functions, respectively.
$SYSSCREENRC
/local/etc/screenrc screen initialization commands
$ISCREENRC
$SCREENRC
$HOME/.iscreenrc
$HOME/.screenrc Read in after /local/etc/screenrc
$ISCREENDIR/S-<login>
$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.
The GR set of ISO 2022 is not supported.
There is no keyboard input translation to VT100 sequences.
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 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.