Screen is a full-screen window manager that multiplexes a physical
terminal between several processes, typically interactive shells. Each
virtual terminal provides the functions of the DEC VT100 terminal and,
in addition, several control functions from the ISO 6429 (ECMA 48, ANSI X3.64)
and ISO 2022 standards (e.g. insert/delete line and support for multiple
character sets). There is a scrollback history buffer for each virtual
terminal and a copy-and-paste mechanism that allows the user to move
text regions between windows.
When screen is called, it creates a single window with a shell in
it (or the specified command) and then gets out of your way so that you
can use the program as you normally would. Then, at any time, you can
create new (full-screen) windows with other programs in them (including
more shells), kill the current window, view a list of the active
windows, turn output logging on and off, copy text between windows, view
the scrollback history, switch between windows, etc. All windows run
their programs completely independent of each other. Programs continue
to run when their window is currently not visible and even when the
whole screen session is detached from the user's terminal.
When a program terminates, screen (per default) kills the window
that contained it. If this window was in the foreground, the display
switches to the previously displayed window; if none are left,
screen exits.
Everything you type is sent to the program running in the current window. The only exception to this is the one keystroke that is used to initiate a command to the window manager. By default, each command begins with a control-a (abbreviated C-a from now on), and is followed by one other keystroke. The command character (see section Command Character) and all the key bindings (see section Key Binding) can be fully customized to be anything you like, though they are always two characters in length.
Screen does not understand the prefix C- to mean control.
Please use the caret notation (^A instead of C-a) as arguments
to e.g. the escape command or the -e option. Screen
will also print out control characters in caret notation.
The standard way to create a new window is to type C-a c. This creates a new window running a shell and switches to that window immediately, regardless of the state of the process running in the current window. Similarly, you can create a new window with a custom command in it by first binding the command to a keystroke (in your `.screenrc' file or at the C-a : command line) and then using it just like the C-a c command. In addition, new windows can be created by running a command like:
screen emacs prog.c
from a shell prompt within a previously created window. This will not
run another copy of screen, but will instead supply the command
name and its arguments to the window manager (specified in the $STY environment
variable) who will use it to create the new window. The above example would
start the emacs editor (editing `prog.c') and switch to its window.
If `/etc/utmp' is writable by screen, an appropriate record
will be written to this file for each window, and removed when the
window is closed. This is useful for working with talk,
script, shutdown, rsend, sccs and other
similar programs that use the utmp file to determine who you are. As
long as screen is active on your terminal, the terminal's own
record is removed from the utmp file. See section Login.
Before you begin to use screen you'll need to make sure you have
correctly selected your terminal type, just as you would for any other
termcap/terminfo program. (You can do this by using tset,
qterm, or just set term=mytermtype, for example.)
If you're impatient and want to get started without doing a lot more
reading, you should remember this one command: C-a ? (see section Key Binding). Typing these two characters will display a list of the
available screen commands and their bindings. Each keystroke is
discussed in the section on keystrokes (see section Default Key Bindings).
Another section (see section Customizing Screen) 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 to use a version of your terminal's termcap that has
automatic margins turned off. This will ensure an accurate
and optimal update of the screen in all circumstances. Most terminals
nowadays have "magic" margins (automatic margins plus usable last
column). This is the VT100 style type and perfectly suited for
screen.
If all you've got is a "true" auto-margin terminal screen
will be content to use it, but updating a character put into the last
position on the screen may not be possible until the screen scrolls or
the character is moved into a safe position in some other way. This
delay can be shortened by using a terminal with insert-character
capability.
See section Special Terminal Capabilities, for more information about telling
screen what kind of terminal you have.
ScreenScreen has the following command-line options:
screen must redraw parts of the display
in order to implement a function.
screen may try to restore its old window sizes when attaching to
resizable terminals (those with `WS' in their descriptions, e.g.
suncmd or some varieties of xterm).
screen, but instead detach a screen session
running elsewhere (see section Detach). `-d' has the same effect as
typing C-a d from the controlling terminal for the session.
`-D' is the equivalent to the power detach key. If no session can
be detached, this option is ignored. In combination with the
-r/-R option more powerful effects can be achieved:
-d -r
-d -R
-d -RR
-D -r
-D -R
-D -RR
screen -list before using this option.
screen session, this option
sets the default command caracter. In a multiuser session all users
added will start off with this command character. But when attaching
to an already running session, this option only changes the command
character of the attaching user.
This option is equivalent to the commands defescape or
escape respectively. (see section Command Character).
defflow command (see section Flow Control).
defscrollback command (see section Copying).
interrupt argument to the defflow command (see section Flow Control). Its use is discouraged.
deflogin command (see section Login).
screen, but instead print a list of session
identification strings (usually of the form pid.tty.host;
see section Session Name). Sessions marked `detached' can be resumed
with screen -r. Those marked `attached' are running and
have a controlling terminal. If the session runs in multiuser mode,
it is marked `multi'. Sessions marked as `unreachable' either
live on a different host or are dead.
An unreachable session is considered dead, when its name matches either the
name of the local host, or the specified parameter, if any.
See the -r flag for a description how to construct matches.
Sessions marked as `dead' should be thoroughly checked and removed.
Ask your system administrator if you are not sure.
Remove sessions with the `-wipe' option.
screen that your auto-margin terminal allows programs to
write to the last column of the last row of the screen without
scrolling. This can also be set in your `.screenrc' by specifying
`xn' in a termcap command (see section Termcap).
screen to ignore the $STY environment variable. When
this option is used, a new session will always be created, regardless of
whether screen is being called from within another screen
session or not. This flag has a special meaning in connection
with the `-d' option:
-m -d
screen in detached mode. This creates a new
session but doesn't attach to it. This is useful for system startup
scripts.
-m -D
screen in detached mode, but doesn't fork
a new process. The command exits if the session terminates.
screen session. No other options (except
combinations with `-d' or `-D') may be specified, though
the session name
(see section Session Name) may be needed to distinguish between multiple
detached screen sessions.
The second form is used to connect to another user's screen session which
runs in multiuser mode. This indicates that screen should look for
sessions in another user's directory. This requires setuid-root.
screen session. If
successful, all other command-line options are ignored. If no detached
session exists, start a new session using the specified options, just as
if `-R' had not been specified. This option is set by default if
screen is run as a login-shell. For combinations with the
`-D'/`-d' option see there.
screen
uses the value of the environment variable $SHELL, or
`/bin/sh' if it is not defined. This option is equivalent to the
shell command (see section Shell).
screen -list and screen -r commands. This option is
equivalent to the sessionname command (see section Session Name).
shelltitle command
(see section Shell).
screen -ls, but remove destroyed
sessions instead of marking them as `dead'.
An unreachable session is considered dead, when its name matches either
the name of the local host, or the explicitly given parameter, if any.
See the -r flag for a description how to construct matches.
Screen
You can modify the default settings for screen to fit your tastes
either through a personal `.screenrc' file which contains commands
to be executed at startup, or on the fly using the colon command.
When screen is invoked, it executes initialization commands from
the files `.screenrc' in the user's home directory and
`/usr/local/etc/screenrc'. These defaults can be overridden in the
following ways:
For the global screenrc file screen searches for the environment
variable $SYSSCREENRC (this override feature may be disabled at
compile-time). The user specific screenrc file is
searched for in $SCREENRC, then
`$HOME/.screenrc'. The command line option `-c'
specifies which file to use (see section Invoking Screen. Commands in these
files are used to set options, bind commands to keys, and to
automatically establish one or more windows at the beginning of
your screen session. Commands are listed one per line, with
empty lines being ignored. A command's arguments are separated by tabs
or spaces, and may be surrounded by single or double quotes. A `#'
turns the rest of the line into a comment, except in quotes.
Unintelligible lines are warned about and ignored. Commands may contain
references to environment variables. The syntax is the shell-like
$VAR or ${VAR}. Note that this causes incompatibility
with previous screen versions, as now the '$'-character has to be
protected with '\' if no variable substitution is intended. A string in
single-quotes is also protected from variable substitution.
Two configuration files are shipped as examples with your screen distribution: `etc/screenrc' and `etc/etcscreenrc'. They contain a number of useful examples for various commands.
Customization can also be done online, with this command:
set keyword no longer exists,
as of version 3.3. Change default settings with commands starting with
`def'. You might think of this as the ex command mode of
screen, with copy as its vi command mode
(see section Copy and Paste).
A command in screen can either be bound to a key, invoked from a
screenrc file, or called from the colon prompt
(see section Customizing Screen). As of version 3.3, all commands can be bound
to keys, although some may be less useful than others.
For a number of real life working examples of the most important
commands see the files `etc/screenrc' and `etc/etcscreenrc'
of your screen distribution.
In this manual, a command definition looks like this:
An argument in square brackets (`[]') is optional. Many commands take an argument of `on' or `off', which is indicated as state in the definition.
As mentioned previously, each keyboard command consists of a C-a followed by one other character. For your convenience, all commands that are bound to lower-case letters are also bound to their control character counterparts (with the exception of C-a a; see below). Thus, both C-a c and C-a C-c can be used to create a window.
The following table shows the default key bindings:
other has the same effect as next.
See section Selecting a Window.
escape command.
See section Command Character.
screen from this terminal. See section Detach.
screen. See section Suspend.
screen. See section Quit.
acladd usernames
aclchg usernames permbits list
acldel username
aclgrp usrname [groupname]
aclumask [users]+\-bits ...
activity message
addacl usernames
acladd. See section Multiuser Session.
allpartial state
at [ident][#|*|%] command [args]
autodetach state
autonuke state
bce [state]
bell_msg [message]
bind key [command [args]]
bind command.
bindkey [opts] [string [cmd args]]
break [duration]
breaktype [tcsendbreak | TCSBRK | TIOCSBRK]
bufferfile [exchange-file]
c1 [state]
caption mode [string]
chacl usernames permbits list
aclchg. See section Multiuser Session.
charset set
chdir [directory]
clear
colon
screen command. See section Colon.
command
compacthist [state]
console [state]
copy
copy_reg [key]
paste instead. See section Registers.
crlf state
debug state
defautonuke state
defbce state
defbreaktype [tcsendbreak | TCSBRK | TIOCSBRK]
defc1 state
defcharset [set]
defescape xy
meta characters. See section Command Character.
defflow fstate
defgr state
defhstatus [status]
defkanji wtype
deflogin state
defmode mode
defmonitor state
defobuflimit limit
defscrollback num
defshell command
defsilence state
defslowpaste msec
defwrap state
defwritelock on|off|auto
defzombie [keys]
detach
screen from the terminal. See section Detach.
digraph
displays
dumptermcap
echo [-n] message
escape xy
meta characters. See section Command Character.
exec [[fdpat] command [args ...]]
fit
flow [fstate]
focus
gr [state]
hardcopy
hardcopy_append state
hardcopydir directory
hardstatus [state]
height [lines]
help
history
hstatus status
info
ins_reg [key]
paste instead. See section Registers.
kanji wtype [dtype]
kill
lastmsg
license
lockscreen
log [state]
logfile filename
login [state]
logtstamp [state]
mapdefault
mapnotnext
maptimeout timo
markkeys string
meta
monitor [state]
msgminwait sec
msgwait sec
multiuser state
nethack state
nethack-like error messages. See section Nethack.
next
nonblock state
number [n]
obuflimit [limit]
only
other
partial state
password [crypted_pw]
paste [src_regs [dest_reg]]
pastefont [state]
pow_break
pow_detach
pow_detach_msg [message]
pow_detach. See section Power Detach.
prev
printcmd [cmd]
process [key]
screen. See section Registers.
quit
readbuf
readreg [reg [file]]
redisplay
register key string
remove
removebuf
reset
screen [opts] [n] [cmd [args]]
scrollback num
select [n]
sessionname [name]
setenv [var [string]]
shell command
shelltitle title
silence [state|seconds]
silencewait seconds
sleep num
slowpaste msec
sorendition [attr [color]]
split
startup_message state
stuff string
su [username [password [password2]]]
suspend
term term
$TERM for new windows. See section Term.
termcap term terminal-tweaks [window-tweaks]
termcap command.
terminfo term terminal-tweaks [window-tweaks]
termcap command.
termcapinfo term terminal-tweaks [window-tweaks]
termcap command.
time
title [windowtitle]
umask [users]+\-bits ...
aclumask. See section aclumask.
unsetenv var
vbell [state]
vbell_msg [message]
vbellwait sec
version
screen version. See section Version.
wall message
width [num]
windows
wrap [state]
writebuf
writelock on|off|auto
xoff
xon
zombie [keys]
This section describes the commands for creating a new window for running programs. When a new window is created, the first available number from the range 0...9 is assigned to it. The number of windows is limited at compile-time by the MAXWIN configuration parameter.
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.
screen, this command (with the given
arguments) is started in the window; otherwise, a shell is created.
Screen has built in some functionality of `cu' and `telnet'. See section Window Types.
Thus, if your `.screenrc' contains the lines
# example for .screenrc: screen 1 screen -fn -t foobar 2 -L telnet foobar
screen creates a shell window (in window #1) and a window with a
TELNET connection to the machine foobar (with no flow-control using the
title `foobar' in window #2) and will write a logfile `screenlog.2'
of the telnet session. If you do not include any
screen commands in your `.screenrc' file, then screen
defaults to creating a single shell window, number zero. When the
initialization is completed, screen switches to the last window
specified in your .screenrc file or, if none, it opens default window
#0.
$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.
defshell is currently a synonym to the shell command.
screen opens, it sets the $TERM
variable to screen by default, unless no description for
screen is installed in the local termcap or terminfo data base.
In that case it pretends that the terminal emulator is `vt100'.
This won't do much harm, as screen is VT100/ANSI compatible. The
use of the term command is discouraged for non-default purpose.
That is, one may want to specify special $TERM settings (e.g. vt100) for
the next screen rlogin othermachine command. Use the command
screen -T vt100 rlogin othermachine rather than setting
and resetting the default.
Screen provides three different window types. New windows are created
with screen's `screen' command (see section Screen Command).
The first parameter to the `screen' command defines which
type of window is created. The different window types are all
special cases of the normal type. They have been added in order
to allow screen to be used efficiently as a console
with 100 or more windows.
<baud_rate>
cs8 or cs7
ixon or -ixon
ixoff or -ixoff
istrip or -istrip
info command shows some of the modem
control lines in the status line.
These may include `RTS', `CTS', `DTR', `CD' and
more. This depends rather on on the available ioctl()'s and system
header files than on the physical capabilities of the serial board.
The name of a logical low (inactive) signal is preceded by an
exclamation mark (`!'), otherwise the signal is logical high (active).
Unsupported but shown signals are usually shown low.
When the CLOCAL status bit is true, the whole set of modem signals is
placed inside curly braces (`{' and `}').
When the CRTSCTS or TIOCSOFTCAR bit is true, the signals
`CTS' or `CD' are shown in parenthesis, respectively.
For tty windows, the command break causes the Data transmission
line (TxD) to go low for a specified period of time. This is expected
to be interpreted as break signal on the other side.
No data is sent and no modem control line is changed when a
break is issued.
//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
e
c
t
screen unless instructed otherwise (see also the
command `term').
w
f
break sends the telnet code
IAC BREAK (decimal 243) to the remote host.
This section describes the commands for switching between windows in an
screen session. The windows are numbered from 0 to 9, and are created
in that order by default (see section New Window).
select 0; there
can be no more than 10 windows present simultaneously (unless screen is
compiled with a higher MAXWIN setting).
The special command select - switches to a blank window.
Perhaps the most useful feature of screen is the way it allows
the user to move a session between terminals, by detaching and
reattaching. This also makes life easier for modem users who have to
deal with unexpected loss of carrier.
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.
screen session (disconnect it from the terminal and
put it into the background). A detached screen can be resumed by
invoking screen with the -r option. (see section Invoking Screen)
screen
and you want to protect your session from reattach attempts by users
that managed to assume your uid. (I.e. any superuser.) If no crypted
password is specified, screen prompts twice a password and places its
encryption in the paste buffer. Default is `none', which disables
password checking.
detach, but also sends a HANGUP signal
to the parent process of screen.screen was started from your login shell.
$LOCKPRG (which must be set in the shell from which screen
is started) and is executed with the user's uid and gid.
Warning: When you leave other shells unlocked and have no password set
on screen, the lock is void: One could easily re-attach from an
unlocked shell. This feature should rather be called
lockterminal.
These commands allow other users to gain access to one single screen
session. When attaching to a multiuser screen the sessionname is
specified as username/sessionname to the -S command line option.
Screen must be compiled with multiuser support to enable features
described here.
acladd, aclchg and
acldel can be used to enable (and disable) other users accessing this
screen.
screen session and performs the equivalent of
aclchg usernames +rwx "#?". To add a user with restricted access,
use the aclchg command below.
Addacl is a synonym to acladd.
Multi-user mode only.
at and others should also be removed or the user may be able
to regain write permission.
Chacl is a synonym to aclchg.
Multi-user mode only.
aclchg command. The special username `?'
predefines the access that not yet known users will be
granted to any window initially. The special username `??'
predefines the access that not yet known users are granted
to any command. Rights of the special username nobody cannot
be changed (see the su command).
Umask is a synonym to aclumask.
writelock off. If the user issues the command
writelock on he keeps the exclusive write permission while switching
to other windows.
screen
password as set with the commands acladd or password.
Su may be useful for the screen administrator to test
multiuser setups.
When the identification fails, the user has
access to the commands available for user `nobody'. These are
detach, license, version, help and
displays.
screen -list the name
shows up with the process-id prepended. If the argument name is
omitted, the name of this session is displayed.$STY
environment variable still reflects the old name. This may result in
confusion. The default is constructed from the tty and host names.
screen. The windows are in the detached state while
screen is suspended. This feature relies on the parent shell
being able to do job control.
screen. Note that on VT100-style
terminals the keys C-4 and C-\ are identical. So 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
(see section Key Binding).
Screen has the ability to display more than one window on the user's display. This is done by splitting the screen in regions, which can contain different windows.
bind j focus down bind k focus up bind t focus top bind b focus bottom
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
always|splitonly [string]
string [string]
always, screen shows a caption
even if only one window is displayed. The default
is `splitonly'.
The second form changes the text used for the caption. You can use
all string escapes (see section String Escapes). Screen uses
a default of `%3n %t'.
You can mix both forms by providing the string as an additional argument.
These commands control the way screen treats individual windows
in a session. See section Virtual Terminal, for commands to control the
terminal emulation itself.
You can customize each window's name in the window display (viewed with
the windows command (see section Windows) by setting it with
one of the title commands. Normally the name displayed is the actual
command name of the program created in the window. However, it is
sometimes useful to distinguish various programs of the same name or to
change the name on-the-fly to reflect the current state of the window.
The default name for all shell windows can be set with the
shelltitle command (see section Shell). You can specify the name you
want for a window with the `-t' option to the screen command
when the window is created (see section Screen Command). To change the name after
the window has been created you can use the title-string escape-sequence
(ESC k name ESC \) and the title command
(C-a A). The former can be output from an application to control the
window's name under software control, and the latter will prompt for a
name when typed. You can also bind predefined names to keys with the
title command to set things quickly without prompting.
screen has a shell-specific heuristic that is enabled by
setting the window's name to search|name and arranging to have a
null title escape-sequence output as a part of your prompt. The
search portion specifies an end-of-prompt search string, while the
name portion specifies the default shell name for the window. If
the name ends in a `:' screen will add what it
believes to be the current command running in the window to the end of
the specified name (e.g. name:cmd). Otherwise the current
command name supersedes the shell name while it is running.
Here's how it works: you must modify your shell prompt to output a null
title-escape-sequence (ESC k ESC \) as a part of your prompt.
The last part of your prompt must be the same as the string you
specified for the search portion of the title. Once this is set
up, screen will use the title-escape-sequence to clear the previous
command name and get ready for the next command. Then, when a newline
is received from the shell, a search is made for the end of the prompt.
If found, it will grab the first word after the matched string and use
it as the command name. If the command name begins with `!',
`%', or `^', screen will use the first word on the
following line (if found) in preference to the just-found name. This
helps csh users get more accurate titles when using job control or
history recall commands.
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='<ESC>[0000m<ESC>k<ESC>\% '
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.
Tcsh handles escape codes in the prompt more intelligently, so you can specify your prompt like this:
set prompt="%{\ek\e\\%}\% "
Bash users will probably want to echo the escape sequence in the PROMPT_COMMAND:
PROMPT_COMMAND='echo -n -e "\033k\033\134"'
(I used `\134' to output a `\' because of a bug in v1.04).
Here are some .screenrc examples:
screen -t top 2 nice top
Adding this line to your .screenrc would start a niced version of the
top command in window 2 named `top' rather than `nice'.
shelltitle '> |csh' screen 1
This file would start a shell using the given shelltitle. The title specified is an auto-title that would expect the prompt and the typed command to look something like the following:
/usr/joe/src/dir> trn
(it looks after the '> ' for the command name). The window status would show the name `trn' while the command was running, and revert to `csh' upon completion.
bind R screen -t '% |root:' su
Having this command in your .screenrc would bind the key sequence
C-a R to the su command and give it an auto-title name of
`root:'. For this auto-title to work, the screen could look
something like this:
% !em emacs file.c
Here the user typed the csh history command !em which ran the
previously entered emacs command. The window status would show
`root:emacs' during the execution of the command, and revert to
simply `root:' at its completion.
bind o title bind E title "" bind u title (unknown)
The first binding doesn't have any arguments, so it would prompt you for a title when you type C-a o. The second binding would clear an auto-titles current setting (C-a E). The third binding would set the current window's title to `(unknown)' (C-a u).
TIOCCONS.
exec command running (see section Exec) then it is killed.
Otherwise the process (e.g. shell) running in the window receives a
HANGUP condition,
the window structure is removed and screen (your display) switches to another
window. When the last window is destroyed, screen exits.
After a kill screen switches to the previously displayed window.
emacs users may find themselves killing their
emacs session when trying to delete the current line. For this
reason, it is probably wise to use a different command character
(see section Command Character) or rebind kill to another key
sequence, such as C-a K (see section Key Binding).
login command except that the default setting for new
windows is changed. This defaults to `on' unless otherwise specified at
compile time (see section Installation). Both commands are only present when
screen has been compiled with utmp support.
bind I login on and bind O
login off will map these keys to be C-a I and C-a O
(see section Key Binding).
-ln was
specified for creation, see section Screen Command).
screen displays a notification in the message line. The
notification message can be redefined by means of the activity
command. Each occurrence of `%' in message is replaced by
the number of the window in which activity has occurred, and each
occurrence of `^G' is replaced by the definition for bell in your
termcap (usually an audible bell). The default message is
'Activity in window %n'
Note that monitoring is off for all windows by default, but can be altered
by use of the monitor command (C-a M).
monitor command except that the default setting for
new windows is changed. Initial setting is `off'.
The current window is marked with a `*'; the previous window is marked with a `-'; all the windows that are logged in are marked with a `$' (see section Login); a background window that has received a bell is marked with a `!'; a background window that is being monitored and has had activity occur is marked with an `@' (see section Monitoring); a window which has output logging turned on is marked with `(L)'; windows occupied by other users are marked with `&' or `&&' if the window is shared by other users; windows in the zombie state are marked with `Z'.
If this list is too long to fit on the terminal's status line only the portion around the current window is displayed.
Screen maintains a hardstatus line for every window. If a window
gets selected, the display's hardstatus will be updated to match
the window's hardstatus line.
The hardstatus line can be changed with the ANSI Application
Program Command (APC): `ESC_<string>ESC\'. As a convenience
for xterm users the sequence `ESC]0..2;<string>^G' is
also accepted.
Each window in a screen session emulates a VT100 terminal, with
some extra functions added. The VT100 emulator is hard-coded, no other
terminal types can be emulated.
The commands described here modify the terminal emulation.
The following is a list of control sequences recognized by
screen. `(V)' and `(A)' indicate VT100-specific and
ANSI- or ISO-specific functions, respectively.
ESC E Next Line
ESC D Index
ESC M Reverse Index
ESC H Horizontal Tab Set
ESC Z Send VT100 Identification String
ESC 7 (V) Save Cursor and Attributes
ESC 8 (V) Restore Cursor and Attributes
ESC [s (A) Save Cursor and Attributes
ESC [u (A) Restore Cursor and Attributes
ESC c Reset to Initial State
ESC g Visual Bell
ESC Pn p Cursor Visibility (97801)
Pn = 6 Invisible
7 Visible
ESC = (V) Application Keypad Mode
ESC > (V) Numeric Keypad Mode
ESC # 8 (V) Fill Screen with E's
ESC \ (A) String Terminator
ESC ^ (A) Privacy Message String (Message Line)
ESC ! Global Message String (Message Line)
ESC k Title Definition String
ESC P (A) Device Control String
Outputs a string directly to the host
terminal without interpretation.
ESC _ (A) Application Program Command (Hardstatus)
ESC ] (A) Operating System Command (Hardstatus, xterm
title hack)
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
?1000 (V) VT200 mouse tracking
ESC [ 5 i (A) Start relay to printer (ANSI Media Copy)
ESC [ 4 i (A) Stop relay to printer (ANSI Media Copy)
ESC [ 8 ; Ph ; Pw t Resize the window to `Ph' lines and
`Pw' columns (SunView special)
ESC [ c Send VT100 Identification String
ESC [ x (V) Send Terminal Parameter Report
ESC [ > c Send Secondary Device Attributes String
ESC [ 6 n Send Cursor Position Report
In order to do a full VT100 emulation screen has to detect
that a sequence of characters in the input stream was generated
by a keypress on the user's keyboard and insert the VT100
style escape sequence. Screen has a very flexible way of doing
this by making it possible to map arbitrary commands on arbitrary
sequences of characters. For standard VT100 emulation the command
will always insert a string in the input buffer of the window
(see also command stuff, see section Paste).
Because the sequences generated by a keypress can
change after a reattach from a different terminal type, it is
possible to bind commands to the termcap name of the keys.
Screen will insert the correct binding after each
reattach. See section Bindkey for further details on the syntax and examples.
Here is the table of the default key bindings. (A) means that the command is executed if the keyboard is switched into application mode.
Key name Termcap name Command
-----------------------------------------------------
Cursor up ku stuff \033[A
stuff \033OA (A)
Cursor down kd stuff \033[B
stuff \033OB (A)
Cursor right kr stuff \033[C
stuff \033OC (A)
Cursor left kl stuff \033[D
stuff \033OD (A)
Function key 0 k0 stuff \033[10~
Function key 1 k1 stuff \033OP
Function key 2 k2 stuff \033OQ
Function key 3 k3 stuff \033OR
Function key 4 k4 stuff \033OS
Function key 5 k5 stuff \033[15~
Function key 6 k6 stuff \033[17~
Function key 7 k7 stuff \033[18~
Function key 8 k8 stuff \033[19~
Function key 9 k9 stuff \033[20~
Function key 10 k; stuff \033[21~
Function key 11 F1 stuff \033[22~
Function key 12 F2 stuff \033[23~
Backspace kb stuff \010
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)
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'.
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.
vbell is switched to `on', but your
terminal does not support a visual bell, the visual bell message is
displayed in the status line when the bell character is received.
Visual bell support of a terminal is
defined by the termcap variable vb. See section `Visual Bell' in The Termcap Manual, for more information on visual bells.
The equivalent terminfo capability is flash.
Per default, vbell is `off', thus the audible bell is used.
vbell is
set to `on' and the terminal does not support a visual bell.
The default message is `Wuff, Wuff!!'.
Without parameter, the current message is shown.
screen 's visual
bell message. The default is 1 second.
+flow automatic flow control, currently on. -flow automatic flow control, currently off. +(+)flow flow control enabled. Agrees with automatic control. -(+)flow flow control disabled. Disagrees with automatic control. +(-)flow flow control enabled. Disagrees with automatic control. -(-)flow flow control disabled. Agrees with automatic control.
The current line wrap setting (`+wrap' indicates enabled, `-wrap' not) is also shown. The flags `ins', `org', `app', `log', `mon' and `nored' are displayed when the window is in insert mode, origin mode, application-keypad mode, has output logging, insert mode, origin mode, application-keypad mode, 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'. Additional modes depending on the type of the window are displayed at the end of the status line (see section Window Types).
If the state machine of the terminal emulator is in a non-default state, the info line is started with a string identifying the current state.
For system information use time.
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.
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.
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".
termcap command (see section Termcap), for more information.
The current setting can be viewed with the section Info command.
For those confined to a hardware terminal, these commands provide a cut and paste facility more powerful than those provided by most windowing systems.
vi-like full screen editor is active, with controls as
outlined below.
crlf is off by default.
When no parameter is given, the state is toggled.
scrollback command except that the default setting
for new windows is changed. Defaults to 100.
markkeys
h=^B:l=^F:$=^E would set some keys to be more familiar to emacs
users.
If your terminal sends characters, that cause you to abort copy mode,
then this command may help by binding these characters to do nothing.
The no-op character is `' and is used like this: markkeys @=L=H
if you do not want to use the `H' or `L' commands any longer.
As shown in this example, multiple keys can be assigned to one function
in a single statement.
h, j, k, l move the cursor line by line or column by column.
0, ^ and $ move to the leftmost column or to the first or last non-whitespace character on the line.
H, M and L move the cursor to the leftmost column of the top, center or bottom line of the window.
+ and - move the cursor to the leftmost column of the next or previous line.
G moves to the specified absolute line (default: end of buffer). | moves to the specified absolute column.
w, b, e move the cursor word by word. C-u and C-d scroll the display up/down by the specified amount of lines while preserving the cursor position. (Default: half screenfull).
C-b and C-f move the cursor up/down a full screen.
g moves to the beginning of the buffer.
% jumps to the specified percentage of the buffer.
Note that Emacs-style movement keys can be specified by a .screenrc
command. (markkeys "h=^B:l=^F:$=^E") There is no simple method for
a full emacs-style keymap, however, as this involves multi-character codes.
The copy range is specified by setting two marks. The text between these marks will be highlighted. Press space to set the first or second mark respectively.
Y and y can be used to mark one whole line or to mark from start of line.
W marks exactly one word.
Any command in copy mode can be prefixed with a number (by pressing digits 0...9) which is taken as a repeat count. Example: C-a C-[ H 10 j 5 Y will copy lines 11 to 15 into the paste buffer.
/ vi-like search forward.
? vi-like search backward.
C-a s emacs style incremental search forward.
C-r emacs style reverse i-search.
There are, however, some keys that act differently here from in
vi. Vi does not allow to yank rectangular blocks of text,
but screen does. Press
c or C to set the left or right margin respectively. If no
repeat count is given, both default to the current cursor position.
Example: Try this on a rather full text screen:
C-a [ M 20 l SPACE c 10 l 5 j C SPACE.
This moves one to the middle line of the screen, moves in 20 columns left,
marks the beginning of the paste buffer, sets the left column, moves 5 columns
down, sets the right column, and then marks the end of
the paste buffer. Now try:
C-a [ M 20 l SPACE 10 l 5 j SPACE
and notice the difference in the amount of text copied.
J joins lines. It toggles between 4 modes: lines separated by a
newline character (012), lines glued seamless, lines separated by a single
space or comma separated lines. Note that you can prepend the newline
character with a carriage return character, by issuing a set crlf
on.
v is for all the vi users who use :set numbers - it
toggles the left margin between column 9 and 1.
a before the final space key turns on append mode. Thus the contents of the paste buffer will not be overwritten, but appended to.
A turns on append mode and sets a (second) mark.
> sets the (second) mark and writes the contents of the paste buffer
to the screen-exchange file (`/tmp/screen-exchange' per default)
once copy-mode is finished. See section Screen-Exchange.
This example demonstrates how to dump the
whole scrollback buffer to that file:
C-a [ g SPACE G $ >.
C-g gives information about the current line and column.
x exchanges the first mark and the current cursor position. You can use this to adjust an already placed mark.
@ does nothing. Absolutely nothing. Does not even exit copy mode.
All keys not described here exit copy mode.
copy, history and readbuf commands.
Other registers can be filled with the register, readreg and
paste commands.
If paste is called with a second argument, the contents of the specified
registers is pasted into the named destination register rather than
the window. If `.' is used as the second argument, the display's paste
buffer is the destination.
Note, that paste uses a wide variety of resources: Usually both, a
current window and a current display are required. But whenever a second
argument is specified no current window is needed. When the source specification
only contains registers (not the paste buffer) then there need not be a current
display (terminal attached), as the registers are a global resource. The
paste buffer exists once for every user.
paste
command. If the slowpaste value is nonzero text is written character by
character.
screen will pause for msec milliseconds after each write
to allow the application to process the input. only use slowpaste if
your underlying system exposes flow control problems while pasting large
amounts of text.
defslowpaste specifies the default for new windows.
readbuf reads the screen-exchange file
into the paste buffer.
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
readreg instead.
paste instead.
screen
input queue. If no argument is given you are prompted for a
register name. The text is parsed as if it had been typed in from the user's
keyboard. This command can be used to bind multiple actions to a single key.
paste command, but with much less overhead.
You cannot paste large buffers with the stuff command. It is most
useful for key bindings. See section Bindkey.
screen reverts
to the default of `/tmp/screen-exchange'. The following example
will paste the system's password file into the screen window (using the
paste buffer, where a copy remains):
C-a : bufferfile /etc/passwd C-a < C-a ] C-a : bufferfile
screen users on the same host. See also
C-a ESC (see section Copying).
csh has the command !! to repeat
the last command executed. screen provides a primitive way of
recalling "the command that started ...": You just type the first
letter of that command, then hit C-a { and screen tries to
find a previous line that matches with the prompt character to the left
of the cursor. This line is pasted into this window's input queue. Thus
you have a crude command history (made up by the visible window and its
scrollback buffer).
Control Input or Output of a window by another filter process. Use with care!
.) connects the file descriptor
to screen. An exclamation mark (!) causes the file descriptor to be
connected to the application-process. A colon (:) combines both.
exec without arguments shows name and arguments of the currently
running subprocess in this window. Only one subprocess can be running per
window.
kill command will affect it instead of
the windows process. Only one subprocess a time can be running in each window.
Abbreviations:
Examples:
!/bin/sh
exec /bin/sh
exec ... /bin/sh
!!stty 19200
exec!stty 19200
exec !.. stty 19200
|less
exec !..| less
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
You may disagree with some of the default bindings (I know I do). The
bind command allows you to redefine them to suit your
preferences.
bind command
By default, most suitable commands are bound to one or more keys
(see section Default Key Bindings; for instance, the command to create a
new window is bound to C-c and c. The bind command
can be used to redefine the key bindings and to define new bindings.
bind commandSome examples:
bind ' ' windows bind ^f screen telnet foobar bind \033 screen -ln -t root -h 1000 9 su
would bind the space key to the command that displays a list of windows (so that the command usually invoked by C-a C-w would also be available as C-a space), bind C-f to the command "create a window with a TELNET connection to foobar", and bind ESC to the command that creates an non-login window with title `root' in slot #9, with a superuser shell and a scrollback buffer of 1000 lines.
meta command)
to y (similar to the `-e' option).
Each argument is either a single character, a two-character
sequence of the form `^x' (meaning C-x), a backslash followed
by an octal number (specifying the ASCII code of the character), or a
backslash followed by a second character, such as `\^' or
`\\'. The default is `^Aa', but `"' is recommended by
one of the authors.
escape except that it is useful for multiuser sessions only.
In a multiuser session
escape changes the command character of the calling user, where
defescape changes the default command characters for users that
will be added later.
Screen), or the
escape .screenrc directive.
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 tring 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 `C-t' an escape character for key-bindings. If you did the above `stuff barfoo' binding, you can enter the word `foo' by typing `C-t foo'. If you want to insert a `C-t' you have to press the key twice (i.e. escape the escape binding).
bindkey -k F1 command
Make the F11 (not F1!) key an alternative screen escape (besides `C-a').
screen can trap flow control characters or pass them to the
program, as you see fit. This is useful when your terminal wants to use
XON/XOFF flow control and you are running a program which wants to use
^S/^Q for other purposes (i.e. emacs).
screen flow control settings
Each window has a flow-control setting that determines how screen deals
with the XON and XOFF characters (and perhaps the interrupt character).
When flow-control is turned off, screen ignores the XON and XOFF
characters, which allows the user to send them to the current program by
simply typing them (useful for the emacs editor, for instance).
The trade-off is that it will take longer for output from a
"normal" program to pause in response to an XOFF. With
flow-control turned on, XON and XOFF characters are used to immediately
pause the output of the current window. You can still send these
characters to the current program, but you must use the appropriate
two-character screen commands (typically C-a q (xon) and C-a
s (xoff)). The xon/xoff commands are also useful for typing C-s and
C-q past a terminal that intercepts these characters.
Each window has an initial flow-control value set with either the
`-f' option or the defflow command. By default the
windows are set to automatic flow-switching. It can then be toggled
between the three states 'fixed on', 'fixed off' and 'automatic'
interactively with the flow command bound to C-a f.
The automatic flow-switching mode deals with flow control using the
TIOCPKT mode (like rlogin does). If the tty driver does not
support TIOCPKT, screen tries to determine the right mode based on the
current setting of the application keypad -- when it is enabled,
flow-control is turned off and visa versa. Of course, you can still
manipulate flow-control manually when needed.
If you're running with flow-control enabled and find that pressing the
interrupt key (usually C-c) does not interrupt the display until another
6-8 lines have scrolled by, try running screen with the `interrupt'
option (add the `interrupt' flag to the flow command in your
.screenrc, or use the `-i' command-line option). This causes the
output that screen has accumulated from the interrupted program
to be flushed. One disadvantage is that the virtual terminal's memory
contains the non-flushed version of the output, which in rare cases can
cause minor inaccuracies in the output. For example, if you switch
screens and return, or update the screen with C-a l you would see
the version of the output you would have gotten without `interrupt'
being on. Also, you might need to turn off flow-control (or use
auto-flow mode to turn it off automatically) when running a program that
expects you to type the interrupt character as input, as the
`interrupt' parameter only takes effect when flow-control is
enabled. If your program's output is interrupted by mistake, a simple
refresh of the screen with C-a l will restore it. Give each mode
a try, and use whichever mode you find more comfortable.
flow command except that the default setting for new
windows is changed. Initial setting is `auto'.
Specifying flow auto interrupt has the same effect as the
command-line options `-fa' and `-i'.
Note that if `interrupt' is enabled, all existing displays are
changed immediately to forward interrupt signals.
screen demands the most out of your terminal so that it can
perform its VT100 emulation most efficiently. These functions provide
means for tweaking the termcap entries for both your physical terminal
and the one simulated by screen.
Usually screen tries to emulate as much of the VT100/ANSI
standard as possible. But if your terminal lacks certain capabilities
the emulation may not be complete. In these cases screen has to
tell the applications that some of the features are missing. This is no
problem on machines using termcap, because screen can use the
$TERMCAP variable to customize the standard screen termcap.
But if you do a rlogin on another machine or your machine supports only
terminfo this method fails. Because of this screen offers a way
to deal with these cases. Here is how it works:
When screen tries to figure out a terminal name for itself, it
first looks for an entry named screen.term, where
term is the contents of your $TERM variable. If no such entry
exists, screen tries `screen' (or `screen-w', if the
terminal is wide (132 cols or more)). If even this entry cannot be
found, `vt100' is used as a substitute.
The idea is that if you have a terminal which doesn't support an
important feature (e.g. delete char or clear to EOS) you can build a new
termcap/terminfo entry for screen (named
`screen.dumbterm') in which this capability has been
disabled. If this entry is installed on your machines you are able to
do a rlogin and still keep the correct termcap/terminfo entry. The
terminal name is put in the $TERM variable of all new windows.
screen also sets the $TERMCAP variable reflecting the
capabilities of the virtual terminal emulated.
Furthermore, the variable $WINDOW is set to the window number of each
window.
The actual set of capabilities supported by the virtual terminal depends
on the capabilities supported by the physical terminal. If, for
instance, the physical terminal does not support underscore mode,
screen does not put the `us' and `ue' capabilities into
the window's $TERMCAP variable, accordingly. However, a minimum number
of capabilities must be supported by a terminal in order to run
screen; namely scrolling, clear screen, and direct cursor
addressing (in addition, screen does not run on hardcopy
terminals or on terminals that over-strike).
Also, you can customize the $TERMCAP value used by screen by
using the termcap command, or by defining the variable
$SCREENCAP prior to startup. When the latter defined, its value will be
copied verbatim into each window's $TERMCAP variable. This can either
be the full terminal definition, or a filename where the terminal
`screen' (and/or `screen-w') is defined.
Note that screen honors the terminfo command if the system
uses the terminfo database rather than termcap. On such machines the
$TERMCAP variable has no effect and you must use the
dumptermcap command (see section Write out the window's termcap entry) and the tic
program to generate terminfo entries for screen windows.
When the boolean `G0' capability is present in the termcap entry
for the terminal on which screen has been called, the terminal
emulation of screen supports multiple character sets. This
allows an application to make use of, for instance, the VT100 graphics
character set or national character sets. The following control
functions from ISO 2022 are supported: `lock shift G0' (`SI'),
`lock shift G1' (`SO'), `lock shift G2', `lock shift
G3', `single shift G2', and `single shift G3'. When a virtual
terminal is created or reset, the ASCII character set is designated as
`G0' through `G3'. When the `G0' capability is present,
screen evaluates the capabilities `S0', `E0', and `C0' if
present. `S0' is the sequence the terminal uses to enable and start
the graphics character set rather than `SI'. `E0' is the
corresponding replacement for `SO'. `C0' gives a character by
character translation string that is used during semi-graphics mode.
This string is built like the `acsc' terminfo capability.
When the `po' and `pf' capabilities are present in the
terminal's termcap entry, applications running in a screen window
can send output to the printer port of the terminal. This allows a user
to have an application in one window sending output to a printer
connected to the terminal, while all other windows are still active (the
printer port is enabled and disabled again for each chunk of output).
As a side-effect, programs running in different windows can send output
to the printer simultaneously. Data sent to the printer is not
displayed in the window. The info command displays a line starting
with `PRIN' while the printer is active.
Some capabilities are only put into the $TERMCAP variable of the virtual
terminal if they can be efficiently implemented by the physical
terminal. For instance, `dl' (delete line) is only put into the
$TERMCAP variable if the terminal supports either delete line itself or
scrolling regions. Note that this may provoke confusion, when the
session is reattached on a different terminal, as the value of $TERMCAP
cannot be modified by parent processes. You can force screen to
include all capabilities in $TERMCAP with the `-a'
command-line option (see section Invoking Screen).
screen stores its
sockets. see section Files Referenced). 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.
termcap command
If your system uses the terminfo database rather than termcap,
screen will understand the terminfo command, which has the
same effects as the termcap command. Two separate commands are
provided, as there are subtle syntactic differences, e.g. when parameter
interpolation (using `%') is required. Note that the termcap names of
the capabilities should also be used with the terminfo command.
In many cases, where the arguments are valid in both terminfo and termcap
syntax, you can use the command termcapinfo, which is just a
shorthand for a pair of termcap and terminfo commands with
identical arguments.
The first argument specifies which terminal(s) should be affected by this definition. You can specify multiple terminal names by separating them with `|'s. Use `*' to match all terminals and `vt*' to match all terminals that begin with `vt'.
Each tweak argument contains one or more termcap defines (separated by `:'s) to be inserted at the start of the appropriate termcap entry, enhancing it or overriding existing values. The first tweak modifies your terminal's termcap, and contains definitions that your terminal uses to perform certain functions. Specify a null string to leave this unchanged (e.g. ""). The second (optional) tweak modifies all the window termcaps, and should contain definitions that screen understands (see section Virtual Terminal).
Some examples:
termcap xterm* xn:hs@
Informs screen that all terminals that begin with `xterm'
have firm auto-margins that allow the last position on the screen to be
updated (xn), but they don't really have a status line (no 'hs' --
append `@' to turn entries off). Note that we assume `xn' for
all terminal names that start with `vt', but only if you don't
specify a termcap command for that terminal.
termcap vt* xn termcap vt102|vt220 Z0=\E[?3h:Z1=\E[?3l
Specifies the firm-margined `xn' capability for all terminals that begin with `vt', and the second line will also add the escape-sequences to switch into (Z0) and back out of (Z1) 132-character-per-line mode if this is a VT102 or VT220. (You must specify Z0 and Z1 in your termcap to use the width-changing commands.)
termcap vt100 "" l0=PF1:l1=PF2:l2=PF3:l3=PF4
This leaves your vt100 termcap alone and adds the function key labels to each window's termcap entry.
termcap h19|z19 am@:im=\E@:ei=\EO dc=\E[P
Takes a h19 or z19 termcap and turns off auto-margins (am@) and enables the insert mode (im) and end-insert (ei) capabilities (the `@' in the `im' string is after the `=', so it is part of the string). Having the `im' and `ei' definitions put into your terminal's termcap will cause screen to automatically advertise the character-insert capability in each window's termcap. Each window will also get the delete-character capability (dc) added to its termcap, which screen will translate into a line-update for the terminal (we're pretending it doesn't support character deletion).
If you would like to fully specify each window's termcap entry, you
should instead set the $SCREENCAP variable prior to running
screen. See section Virtual Terminal, for the details of the
screen terminal emulation. See section `Termcap' in The Termcap Manual, for more information on termcap definitions.
The following table describes all terminal capabilities that are
recognized by screen and are not in the termcap manual
(see section `Termcap' in The Termcap Manual).
You can place these capabilities in your termcap entries (in
`/etc/termcap') or use them with the commands termcap,
terminfo and termcapinfo in your screenrc files. It is
often not possible to place these capabilities in the terminfo database.
screen now uses the standard
`xn' instead.
flow off. The opposite of this
capability is `nx'.
autonuke command except that the default setting for
new displays is also changed. Initial setting is off.
Note that you can use the special AN terminal capability if you
want to have a terminal type dependent setting.
xterm), you can set it to some
higher value. If no argument is specified, the current setting is displayed.
This property is set per display, not per window.
obuflimit command except that the default setting for new
displays is also changed. Initial setting is 256 bytes. Note that you can use
the special OL terminal capability if you want to have a terminal
type dependent limit.
Screen has a powerful mechanism to translate characters to
arbitrary strings depending on the current font and terminal type.
Use this feature if you want to work with a common standard character
set (say ISO8851-latin1) even on terminals that scatter the more
unusual characters over several national language font pages.
Syntax:
XC=<charset-mapping>{,,<charset-mapping>}
<charset-mapping> := <designator><template>{,<mapping>}
<mapping> := <char-to-be-mapped><template-arg>
The things in braces may be repeated any number of times.
A <charset-mapping> tells screen how to map characters in font <designator> (`B': Ascii, `A': UK, `K': german, etc.) to strings. Every <mapping> describes to what string a single character will be translated. A template mechanism is used, as most of the time the codes have a lot in common (for example strings to switch to and from another charset). Each occurrence of `%' in <template> gets substituted with the template-arg specified together with the character. If your strings are not similar at all, then use `%' as a template and place the full string in <template-arg>. A quoting mechanism was added to make it possible to use a real `%'. The `\' character quotes the special characters `\', `%', and `,'.
Here is an example:
termcap hp700 'XC=B\E(K%\E(B,\304[,\326\\\\,\334]'
This tells screen, how to translate ISOlatin1 (charset `B')
upper case umlaut characters on a hp700 terminal that has a
german charset. `\304' gets translated to
`\E(K[\E(B' and so on.
Note that this line gets parsed *three* times before the internal
lookup table is built, therefore a lot of quoting is needed to
create a single `\'.
Another extension was added to allow more emulation: If a mapping translates the unquoted `%' char, it will be sent to the terminal whenever screen switches to the corresponding <designator>. In this special case the template is assumed to be just `%' because the charset switch sequence and the character mappings normally haven't much in common.
This example shows one use of the extension:
termcap xterm 'XC=K%,%\E(B,[\304,\\\\\326,]\334'
Here, a part of the german (`K') charset is emulated on an xterm. If screen has to change to the `K' charset, `\E(B' will be sent to the terminal, i.e. the ASCII charset is used instead. The template is just `%', so the mapping is straightforward: `[' to `\304', `\' to `\326', and `]' to `\334'.
screen displays informational messages and other diagnostics in a
message line at the bottom of the screen. If your terminal has a
status line defined in its termcap, screen will use this for displaying
its messages, otherwise the last line of the screen will be temporarily
overwritten and output will be momentarily interrupted. The message
line is automatically removed after a few seconds delay, but it can also
be removed early (on terminals without a status line) by beginning to
type.
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 ASCII ESC and `^' is a literal caret or up-arrow.
always]lastline|message|ignore [string]
string [string]
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 mechanism and
ignore tells screen never to display the hardstatus.
If you prepend the word always to the type, screen will use
the type even if the terminal supports a hardstatus line.
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 `\E]0;^G' or `\E_\\') is
displayed.
You can customize this to any string you like including
string escapes (see section String Escapes).
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.
screen delays a new message when another is
currently displayed. Defaults to 1 second.
screen is not
disturbed by other activity. Defaults to 5 seconds.
This section describes the commands for keeping a record of your session.
hardcopy_append command.
screen will append to the
`hardcopy.n' files created by the command hardcopy;
otherwise, these files are overwritten each time.
screen
will wait before flushing the logfile buffer to the file-system. The
default value is 10 seconds.
after secs
string string
This section describes commands which are only useful in the `.screenrc' file, for use at startup.
screen users with a
'message of the day'. Typically installed in a global 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.
echo.
The commands described here do not fit well under any of the other categories.
At changes the context (the `current window' or `current display'
setting) 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.
Note that the # character works as a comment introducer when it is
preceded by whitespace. This can be escaped by prefixing # with 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. stuff, \*Qprocess or paste) require
that a display is associated with the target windows. These commands may not
work correctly under at looping over windows.
defbreaktype. This will be changed in
the future.
Calling breaktype with no parameter displays the break setting for the
current window.
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.
screen has been compiled with
option -DDEBUG debugging is available and is turned on per default.
Note that this command only affects debugging output from the main
`SCREEN' process correctly. Debug output from attacher processes can only
be turned off once and forever.
screen is
started without options, which should be often enough.
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 (see section Installation). The default setting is then
determined by the presence of the environment variable
$NETHACKOPTIONS.
Nonblock is initially off for all displays.
silencewait command or by specifying a number of seconds instead of
on or off. Silence is initially off for all windows.
silence command except that the default setting for
new windows is changed. Initial setting is `off'.
info (see section Info).
kill command may be used to remove the window. Pressing the first key
in the dead window has the same effect. Pressing the second key, however,
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
the process terminates.
As the zombie setting is affected 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.
po/pf for printing 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 an argument 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.
Screen provides an escape mechanism to insert information like the
current time into messages or file names. The escape character
is % with one exception: inside of a window's hardstatus
^% (^E) is used instead.
Here is the full list of supported escapes:
%
a
am or pm
A
AM or PM
c
HH:MM in 24h format
C
HH:MM in 12h format
d
D
h
l
m
M
n
s
t
u
w
W
y
Y
?
%? is displayed only if an escape expands
to an nonempty string
:
%?
The c and C escape may be qualified with a 0 to
make screen use
zero instead of space as fill character. The n escape understands
a length qualifier (e.g. %3n).
COLUMNS
HOME
LINES
LOCKPRG
NETHACKOPTIONS
nethack option.
PATH
SCREENCAP
TERMCAP value.
SCREENDIR
SCREENRC
SHELL
STY
screen is invoked, and the environment variable
STY is set, then it creates only a window in the running screen
session rather than starting a new session.
SYSSCREENRC
TERM
TERMCAP
screen distribution package for private and
global initialization files.
$SYSSCREENRC'
screen initialization commands
$SCREENRC'
$HOME/.iscreenrc'
$HOME/.screenrc'
$SCREENDIR/S-login'
dumptermcap command
screen interprocess communication buffer
$LOCKPRG'
Authors
=======
Originally created by Oliver Laumann, this latest version was produced by Wayne Davison, Juergen Weigert and Michael Schroeder.
Contributors
============
Ken Beal (kbeal@amber.ssd.csd.harris.com),
Rudolf Koenig (rfkoenig@informatik.uni-erlangen.de),
Toerless Eckert (eckert@informatik.uni-erlangen.de),
Wayne Davison (davison@borland.com),
Patrick Wolfe (pat@kai.com, kailand!pat),
Bart Schaefer (schaefer@cse.ogi.edu),
Nathan Glasser (nathan@brokaw.lcs.mit.edu),
Larry W. Virden (lvirden@cas.org),
Howard Chu (hyc@hanauma.jpl.nasa.gov),
Tim MacKenzie (tym@dibbler.cs.monash.edu.au),
Markku Jarvinen (mta@{cc,cs,ee}.tut.fi),
Marc Boucher (marc@CAM.ORG),
Doug Siebert (dsiebert@isca.uiowa.edu),
Ken Stillson (stillson@tsfsrv.mitre.org),
Ian Frechett (frechett@spot.Colorado.EDU),
Brian Koehmstedt (bpk@gnu.ai.mit.edu),
Don Smith (djs6015@ultb.isc.rit.edu),
Frank van der Linden (vdlinden@fwi.uva.nl),
Martin Schweikert (schweik@cpp.ob.open.de),
David Vrona (dave@sashimi.lcu.com),
E. Tye McQueen (tye%spillman.UUCP@uunet.uu.net),
Matthew Green (mrg@mame.mu.oz.au),
Christopher Williams (cgw@unt.edu),
Matt Mosley (mattm@access.digex.net),
Gregory Neil Shapiro (gshapiro@wpi.WPI.EDU),
Jason Merrill (jason@jarthur.Claremont.EDU).
Version
=======
This manual describes version 3.9.8 of the screen
program. Its roots are a merge of a custom version 2.3PR7 by Wayne
Davison and several enhancements to Oliver Laumann's version 2.0.
Note that all versions numbered 2.x are copyright by Oliver Laumann.
See also See section Availability.
Just like any other significant piece of software, screen has a
few bugs and missing features. Please send in a bug report if you have
found a bug not mentioned here.
screen has no clue about double-high or double-wide characters.
But this is the only area where vttest is allowed to fail.
$TERMCAP
when reattaching under a different terminal type.
$TERMCAP may not have any effects.
screen does not make use of hardware tabs.
screen must be installed setuid root on most systems
in order to be able to
correctly change the owner of the tty device file for each window.
Special permission may also be required to write the file
`/etc/utmp'.
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.
screen may not automatically detach
(or quit) unless the device driver sends a HANGUP signal. To detach such a
screen session use the -D or -d command line option.
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.
If you find a bug in Screen, please send electronic mail to
`screen@uni-erlangen.de', and also to
`bug-gnu-utils@prep.ai.mit.edu'. Include the version number
of Screen which you are using. Also include in your message the
hardware and operating system, the compiler used to compile, a
description of the bug behavior, and the conditions that triggered the
bug. Please recompile screen with the `-DDEBUG' options
enabled, reproduce the bug, and have a look at the debug output written to
the directory `/tmp/debug'. If necessary quote suspect passages from the
debug output and show the contents of your `config.h' if it matters.
Screen is available under the GNU copyleft.
The latest official release of screen available via anonymous
ftp from `prep.ai.mit.edu', `nic.funet.fi' or any other
GNU distribution site. The home site of
screen is `ftp.uni-erlangen.de
(131.188.3.71)', in the directory `pub/utilities/screen'.
The subdirectory `private' contains the latest beta testing release.
If you want to help, send a note to screen@uni-erlangen.de.
Since screen uses pseudo-ttys, the select system call, and
UNIX-domain sockets/named pipes, it will not run under a system that
does not include these features of 4.2 and 4.3 BSD UNIX.
The socket directory defaults either to `$HOME/.screen' or simply to
`/tmp/screens' or preferably to `/usr/local/screens' chosen at
compile-time. If screen is installed
setuid root, then the administrator should compile screen with an
adequate (not NFS mounted) SOCKDIR. If screen is not
running setuid-root, the user can specify any mode 700 directory in the
environment variable $SCREENDIR.
To compile and install screen:
The screen package comes with a GNU Autoconf configuration
script. Before you compile the package run
sh ./configure
This will create a `config.h' and `Makefile' for your machine.
If configure fails for some reason, then look at the examples and
comments found in the `Makefile.in' and `config.h.in' templates.
Rename `config.status' to `config.status.machine' when
you want to keep configuration data for multiple architectures. Running
sh ./config.status.machine recreates your configuration
significantly faster than rerunning configure.
Read through the "User Configuration" section of `config.h', and verify
that it suits your needs.
A comment near the top of this section explains why it's best to
install screen setuid to root.
Check for the place for the global `screenrc'-file and for the socket
directory.
Check the compiler used in `Makefile', the prefix path where to install
screen. Then run
make
If make fails to produce one of the files `term.h', `comm.h'
or `tty.c', then use filename.x.dist instead.
For additional information about installation of screen refer to the
file `INSTALLATION', coming with this package.
This is a list of all the commands supported by screen.
This is a list of the default key bindings.
The leading escape character (see section Command Character) has been omitted from the key sequences, since it is the same for all bindings.
This document was generated on 29 November 2000 using the texi2html translator version 1.51.