Provided by: screen_4.9.1-1build1_amd64 
NAME
screen - screen manager with VT100/ANSI terminal emulation
SYNOPSIS
screen [ -options ] [ cmd [ args ] ]
screen -r [[pid.]tty[.host]]
screen -r sessionowner/[[pid.]tty[.host]]
DESCRIPTION
Screen is a full-screen window manager that multiplexes a physical terminal between several processes
(typically interactive shells). Each virtual terminal provides the functions of a DEC VT100 terminal
and, in addition, several control functions from the ISO 6429 (ECMA 48, ANSI X3.64) and ISO 2022
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 moving text regions
between windows.
When screen is called, it creates a single window with a shell in it (or the specified command) and then
gets out of your way so that you can use the 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 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. All windows run
their programs completely independent of each other. Programs continue to run when their window is
currently not visible and even when the whole screen session is detached from the user's terminal. When
a program terminates, screen (per default) kills the window that contained it. If this window was in the
foreground, the display switches to the previous window; if none are left, screen exits. Shells usually
distinguish between running as login-shell or sub-shell. Screen runs them as sub-shells, unless told
otherwise (See shell .screenrc command).
Everything you type is sent to the program running in the current window. The only exception to this is
the one keystroke that is used to initiate a command to the window manager. By default, each command
begins with a control-a (abbreviated C-a from now on), and is followed by one other keystroke. The
command character and all the key bindings can be fully customized to be anything you like, though they
are always two characters in length.
Screen does not understand the prefix C- to mean control, although this notation is used in this manual
for readability. Please use the caret notation (^A instead of C-a) as arguments to e.g. the escape
command or the -e option. Screen will also print out control characters in caret notation.
The standard way to create a new window is to type C-a c. This creates a new window running a shell and
switches to that window immediately, regardless of the state of the process running in the current
window. Similarly, you can create a new window with a custom command in it by first binding the command
to a keystroke (in your .screenrc file or at the C-a : command line) and then using it just like the C-a
c command. In addition, new windows can be created by running a command like:
screen emacs prog.c
from a shell prompt within a previously created window. This will not run another copy of screen, but
will instead supply the command name and its arguments to the window manager (specified in the $STY
environment variable) who will use it to create the new window. The above example would start the emacs
editor (editing prog.c) and switch to its window. - Note that you cannot transport environment variables
from the invoking shell to the application (emacs in this case), because it is forked from the parent
screen process, not from the invoking shell.
If /run/utmp is writable by screen, an appropriate record will be written to this file for each window,
and removed when the window is terminated. This is useful for working with talk, script, shutdown,
rsend, sccs and other similar programs that use the utmp file to determine who you are. As long as screen
is active on your terminal, the terminal's own record is removed from the utmp file. See also C-a L.
GETTING STARTED
Before you begin to use screen you'll need to make sure you have correctly selected your terminal type,
just as you would for any other termcap/terminfo program. (You can do this by using test for example.)
If you're impatient and want to get started without doing a lot more reading, you should remember this
one command: C-a ?. Typing these two characters will display a list of the available screen commands
and their bindings. Each keystroke is discussed in the section DEFAULT KEY BINDINGS. The manual section
CUSTOMIZATION deals with the contents of your .screenrc.
If your terminal is a true auto-margin terminal (it doesn't allow the last position on the screen to be
updated without scrolling the screen) consider using a version of your terminal's termcap that has
automatic margins turned off. This will ensure an accurate and optimal update of the screen in all
circumstances. Most terminals nowadays have magic margins (automatic margins plus usable last column).
This is the VT100 style type and perfectly suited for screen. If all you've got is a true auto-margin
terminal screen will be content to use it, but updating a character put into the last position on the
screen may not be possible until the screen scrolls or the character is moved into a safe position in
some other way. This delay can be shortened by using a terminal with insert-character capability.
COMMAND-LINE OPTIONS
Screen has the following command-line options:
-a include all capabilities (with some minor exceptions) in each window's termcap, even if screen must
redraw parts of the display in order to implement a function.
-A Adapt the sizes of all windows to the size of the current terminal. By default, screen tries to
restore its old window sizes when attaching to resizable terminals (those with WS in its
description, e.g. suncmd or some xterm).
-c file
override the default configuration file from $HOME/.screenrc to file.
-d|-D [pid.tty.host]
does not start screen, but detaches the elsewhere running screen session. It has the same effect as
typing C-a d from screen's controlling terminal. -D is the equivalent to the power detach key. If
no session can be detached, this option is ignored. In combination with the -r/-R option more
powerful effects can be achieved:
-d -r Reattach a session and if necessary detach it first.
-d -R Reattach a session and if necessary detach or even create it first.
-d -RR Reattach a session and if necessary detach or create it. Use the first session if more than one
session is available.
-D -r Reattach a session. If necessary detach and logout remotely first.
-D -R Attach here and now. In detail this means: If a session is running, then reattach. If necessary
detach and logout remotely first. If it was not running create it and notify the user. This is
the author's favorite.
-D -RR Attach here and now. Whatever that means, just do it.
Note: It is always a good idea to check the status of your sessions by means of screen -list.
-e xy
specifies the command character to be x and the character generating a literal command character to
y (when typed after the command character). The default is C-a and `a', which can be specified as
-e^Aa. When creating a screen session, this option sets the default command character. In a
multiuser session all users added will start off with this command character. But when attaching to
an already running session, this option changes only the command character of the attaching user.
This option is equivalent to either the commands defescape or escape respectively.
-f, -fn, and -fa
turns flow-control on, off, or automatic switching mode. This can also be defined through the
defflow .screenrc command.
-h num
Specifies the history scrollback buffer to be num lines high.
-i will cause the interrupt key (usually C-c) to interrupt the display immediately when flow-control is
on. See the defflow .screenrc command for details. The use of this option is discouraged.
-l and -ln
turns login mode on or off (for /run/utmp updating). This can also be defined through the deflogin
.screenrc command.
-ls [match]
-list [match]
does not start screen, but prints a list of pid.tty.host strings and creation timestamps identifying
your screen sessions. Sessions marked `detached' can be resumed with screen -r. Those marked
`attached' are running and have a controlling terminal. If the session runs in multiuser mode, it is
marked `multi'. Sessions marked as `unreachable' either live on a different host or are `dead'. An
unreachable session is considered dead, when its name matches either the name of the local host, or
the specified parameter, if any. See the -r flag for a description how to construct matches.
Sessions marked as `dead' should be thoroughly checked and removed. Ask your system administrator
if you are not sure. Remove sessions with the -wipe option.
-L tells screen to turn on automatic output logging for the windows.
-Logfile file
By default logfile name is screenlog.0. You can set new logfile name with the -Logfile option.
-m causes screen to ignore the $STY environment variable. With screen -m creation of a new session is
enforced, regardless whether screen is called from within another screen session or not. This flag
has a special meaning in connection with the `-d' option:
-d -m Start screen in detached mode. This creates a new session but doesn't attach to it. This is
useful for system startup scripts.
-D -m This also starts screen in detached mode, but doesn't fork a new process. The command exits if
the session terminates.
-O selects an optimal output mode for your terminal rather than true VT100 emulation (only affects
auto-margin terminals without `LP'). This can also be set in your .screenrc by specifying `OP' in a
termcap command.
-p number_or_name|-|=|+
Preselect a window. This is useful when you want to reattach to a specific window or you want to
send a command via the -X option to a specific window. As with screen's select command, - selects
the blank window. As a special case for reattach, = brings up the windowlist on the blank window,
while a + will create a new window. The command will not be executed if the specified window could
not be found.
-q Suppress printing of error messages. In combination with -ls the exit value is as follows: 9
indicates a directory without sessions. 10 indicates a directory with running but not attachable
sessions. 11 (or more) indicates 1 (or more) usable sessions. In combination with -r the exit value
is as follows: 10 indicates that there is no session to resume. 12 (or more) indicates that there
are 2 (or more) sessions to resume and you should specify which one to choose. In all other cases
-q has no effect.
-Q Some commands now can be queried from a remote session using this flag, e.g. screen -Q windows. The
commands will send the response to the stdout of the querying process. If there was an error in the
command, then the querying process will exit with a non-zero status.
The commands that can be queried now are:
echo
info
lastmsg
number
select
time
title
windows
-r [pid.tty.host]
-r sessionowner/[pid.tty.host]
resumes a detached screen session. No other options (except combinations with -d/-D) may be
specified, though an optional prefix of [pid.]tty.host may be needed to distinguish between multiple
detached screen sessions. The second form is used to connect to another user's screen session which
runs in multiuser mode. This indicates that screen should look for sessions in another user's
directory. This requires setuid-root.
-R resumes screen only when it's unambiguous which one to attach, usually when only one screen is
detached. Otherwise lists available sessions. -RR attempts to resume the youngest (in terms of
creation time) detached screen session it finds. If successful, all other command-line options are
ignored. If no detached session exists, starts a new session using the specified options, just as
if -R had not been specified. The option is set by default if screen is run as a login-shell
(actually screen uses -xRR in that case). For combinations with the -d/-D option see there. Note:
Time-based session selection is a Debian addition.
-s program
sets the default shell to the program specified, instead of the value in the environment variable
$SHELL (or /bin/sh if not defined). This can also be defined through the shell .screenrc command.
See also there.
-S sessionname
When creating a new session, this option can be used to specify a meaningful name for the session.
This name identifies the session for screen -list and screen -r actions. It substitutes the default
[tty.host] suffix. This name should not be longer then 80 symbols.
-t name
sets the title (a.k.a.) for the default shell or specified program. See also the shelltitle
.screenrc command.
-T term
Set the $TERM environment variable using the specified term as opposed to the default setting of
screen.
-U Run screen in UTF-8 mode. This option tells screen that your terminal sends and understands UTF-8
encoded characters. It also sets the default encoding for new windows to `utf8'.
-v Print version number.
-wipe [match]
does the same as screen -ls, but removes destroyed sessions instead of marking them as `dead'. An
unreachable session is considered dead, when its name matches either the name of the local host, or
the explicitly given parameter, if any. See the -r flag for a description how to construct matches.
-x Attach to a not detached screen session. (Multi display mode). Screen refuses to attach from within
itself. But when cascading multiple screens, loops are not detected; take care.
-X Send the specified command to a running screen session. You may use the -S option to specify the
screen session if you have several screen sessions running. You can use the -d or -r option to tell
screen to look only for attached or detached screen sessions. Note that this command doesn't work if
the session is password protected.
-4 Resolve hostnames only to IPv4 addresses.
-6 Resolve hostnames only to IPv6 addresses.
DEFAULT KEY BINDINGS
As mentioned, each screen command consists of a C-a followed by one other character. For your
convenience, all commands that are bound to lower-case letters are also bound to their control character
counterparts (with the exception of C-a a; see below), thus, C-a c as well as C-a C-c can be used to
create a window. See section CUSTOMIZATION for a description of the command.
The following table shows the default key bindings. The trailing commas in boxes with multiple keystroke
entries are separators, not part of the bindings.
──────────────────────────────────────────────────────────────────
C-a ' (select) Prompt for a window name or
number to switch to.
──────────────────────────────────────────────────────────────────
C-a " (windowlist -b) Present a list of all
windows for selection.
──────────────────────────────────────────────────────────────────
C-a digit (select 0-9) Switch to window number 0 -
9
──────────────────────────────────────────────────────────────────
C-a - (select -) Switch to window number 0 -
9, or to the blank window.
──────────────────────────────────────────────────────────────────
C-a tab (focus) Switch the input focus to
the next region. See also
split, remove, only.
──────────────────────────────────────────────────────────────────
C-a C-a (other) Toggle to the window
displayed previously. Note
that this binding defaults
to the command character
typed twice, unless
overridden. For instance,
if you use the option -e]x,
this command becomes ]].
──────────────────────────────────────────────────────────────────
C-a a (meta) Send the command character
(C-a) to window. See escape
command.
──────────────────────────────────────────────────────────────────
C-a A (title) Allow the user to enter a
name for the current window.
──────────────────────────────────────────────────────────────────
C-a b, (break) Send a break to window.
C-a C-b
──────────────────────────────────────────────────────────────────
C-a B (pow_break) Reopen the terminal line and
send a break.
──────────────────────────────────────────────────────────────────
C-a c, (screen) Create a new window with a
C-a C-c shell and switch to that
window.
──────────────────────────────────────────────────────────────────
C-a C (clear) Clear the screen.
──────────────────────────────────────────────────────────────────
C-a d, (detach) Detach screen from this
C-a C-d terminal.
──────────────────────────────────────────────────────────────────
C-a D D (pow_detach) Detach and logout.
──────────────────────────────────────────────────────────────────
C-a f, (flow) Toggle flow on, off or auto.
C-a C-f
──────────────────────────────────────────────────────────────────
C-a F (fit) Resize the window to the
current region size.
──────────────────────────────────────────────────────────────────
C-a C-g (vbell) Toggles screen's visual bell
mode.
──────────────────────────────────────────────────────────────────
C-a h (hardcopy) Write a hardcopy of the
current window to the file
hardcopy.n.
──────────────────────────────────────────────────────────────────
C-a H (log) Begins/ends logging of the
current window to the file
screenlog.n.
──────────────────────────────────────────────────────────────────
C-a i, (info) Show info about this window.
C-a C-i
──────────────────────────────────────────────────────────────────
C-a k, (kill) Destroy current window.
C-a C-k
──────────────────────────────────────────────────────────────────
C-a l, (redisplay) Fully refresh current
C-a C-l window.
──────────────────────────────────────────────────────────────────
C-a L (login) Toggle this windows login
slot. Available only if
screen is configured to
update the utmp database.
──────────────────────────────────────────────────────────────────
C-a m, (lastmsg) Repeat the last message
C-a C-m displayed in the message
line.
──────────────────────────────────────────────────────────────────
C-a M (monitor) Toggles monitoring of the
current window.
──────────────────────────────────────────────────────────────────
C-a space, (next) Switch to the next window.
C-a n,
C-a C-n
──────────────────────────────────────────────────────────────────
C-a N (number) Show the number (and title)
of the current window.
──────────────────────────────────────────────────────────────────
C-a backspace, (prev) Switch to the previous
C-a C-h, window (opposite of C-a n).
C-a p,
C-a C-p
──────────────────────────────────────────────────────────────────
C-a q, (xon) Send a control-q to the
C-a C-q current window.
──────────────────────────────────────────────────────────────────
C-a Q (only) Delete all regions but the
current one. See also
split, remove, focus.
──────────────────────────────────────────────────────────────────
C-a r, (wrap) Toggle the current window's
C-a C-r line-wrap setting (turn the
current window's automatic
margins on and off).
──────────────────────────────────────────────────────────────────
C-a s, (xoff) Send a control-s to the
C-a C-s; current window.
──────────────────────────────────────────────────────────────────
C-a S (split) Split the current region
horizontally into two new
ones. See also only,
remove, focus.
──────────────────────────────────────────────────────────────────
C-a t, (time) Show system information.
C-a C-t
──────────────────────────────────────────────────────────────────
C-a v (version) Display the version and
compilation date.
──────────────────────────────────────────────────────────────────
C-a C-v (digraph) Enter digraph.
C-a w, (windows) Show a list of window.
C-a C-w
──────────────────────────────────────────────────────────────────
C-a W (width) Toggle 80/132 columns.
──────────────────────────────────────────────────────────────────
C-a x or C-a C-x (lockscreen) Lock this terminal.
──────────────────────────────────────────────────────────────────
C-a X (remove) Kill the current region.
See also split, only, focus.
──────────────────────────────────────────────────────────────────
C-a z, (suspend) Suspend screen. Your system
C-a C-z must support BSD-style job-
control.
──────────────────────────────────────────────────────────────────
C-a Z (reset) Reset the virtual terminal
to its power-on values.
──────────────────────────────────────────────────────────────────
C-a . (dumptermcap) Write out a .termcap file.
──────────────────────────────────────────────────────────────────
C-a ? (help) Show key bindings.
──────────────────────────────────────────────────────────────────
C-a \ (quit) Kill all windows and
terminate screen.
──────────────────────────────────────────────────────────────────
C-a : (colon) Enter command line mode.
──────────────────────────────────────────────────────────────────
C-a [, (copy) Enter copy/scrollback mode.
C-a C-[,
C-a esc
──────────────────────────────────────────────────────────────────
C-a C-], (paste .) Write the contents of the
C-a ] paste buffer to the stdin
queue of the current window.
──────────────────────────────────────────────────────────────────
C-a {, (history) Copy and paste a previous
C-a } (command) line.
──────────────────────────────────────────────────────────────────
C-a > (writebuf) Write paste buffer to a
file.
──────────────────────────────────────────────────────────────────
C-a < (readbuf) Reads the screen-exchange
file into the paste buffer.
──────────────────────────────────────────────────────────────────
C-a = (removebuf) Removes the file used by C-a
< and C-a >.
──────────────────────────────────────────────────────────────────
C-a , (license) Shows where screen comes
from, where it went to and
why you can use it.
──────────────────────────────────────────────────────────────────
C-a _ (silence) Start/stop monitoring the
current window for
inactivity.
──────────────────────────────────────────────────────────────────
C-a | (split -v) Split the current region
vertically into two new
ones.
──────────────────────────────────────────────────────────────────
C-a * (displays) Show a listing of all
currently attached displays.
──────────────────────────────────────────────────────────────────
CUSTOMIZATION
The socket directory defaults either to $HOME/.screen or simply to /tmp/screens or preferably to
/run/screen chosen at compile-time. If screen is installed setuid-root, then the administrator should
compile screen with an adequate (not NFS mounted) socket directory. If screen is not running setuid-root,
the user can specify any mode 700 directory in the environment variable $SCREENDIR.
When screen is invoked, it executes initialization commands from the files /etc/screenrc and defaults
that 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 in $SCREENRC, then $HOME/.screenrc. The command line option -c takes
precedence over the above user screenrc files.
Commands in these files are used to set options, bind functions to keys, and to automatically establish
one or more windows at the beginning of your screen session. Commands are listed one per line, with
empty lines being ignored. A command's arguments are separated by tabs or spaces, and may be surrounded
by single or double quotes. A `#' turns the rest of the line into a comment, except in quotes.
Unintelligible lines are warned about and ignored. Commands may contain references to environment
variables. The syntax is the shell-like "$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 shall be performed. 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 'on-line'. To enter the command mode type `C-a :'. Note that commands
starting with def change default values, while others change current settings.
The following commands are available:
acladd usernames [crypted-pw]
addacl usernames
Enable users to fully access this screen session. Usernames can be one user or a comma separated list of
users. This command enables to attach to the screen session and performs the equivalent of `aclchg
usernames +rwx "#?"'. executed. To add a user with restricted access, use the `aclchg' command below.
If an optional second parameter is supplied, it should be a crypted password for the named user(s).
`Addacl' is a synonym to `acladd'. Multi user mode only.
aclchg usernames permbits list
chacl usernames permbits list
Change permissions for a comma separated list of users. Permission bits are represented as `r', `w' and
`x'. Prefixing `+' grants the permission, `-' removes it. The third parameter is a comma separated list
of commands and/or windows (specified either by number or title). The special list `#' refers to all
windows, `?' to all commands. if usernames consists of a single `*', all known users are affected.
A command can be executed when the user has the `x' bit for it. The user can type input to a window when
he has its `w' bit set and no other user obtains a writelock for this window. Other bits are currently
ignored. To withdraw the writelock from another user in window 2: `aclchg username -w+w 2'. To allow
read-only access to the session: `aclchg username -w "#"'. As soon as a user's name is known to screen he
can attach to the session and (per default) has full permissions for all command and windows. Execution
permission for the acl commands, `at' and others should also be removed or the user may be able to regain
write permission. Rights of the special username nobody cannot be changed (see the su command). `Chacl'
is a synonym to `aclchg'. Multi user mode only.
acldel username
Remove a user from screen's access control list. If currently attached, all the user's displays are
detached from the session. He cannot attach again. Multi user mode only.
aclgrp username [groupname]
Creates groups of users that share common access rights. The name of the group is the username of the
group leader. Each member of the group inherits the permissions that are granted to the group leader.
That means, if a user fails an access check, another check is made for the group leader. A user is
removed from all groups the special value none is used for groupname. If the second parameter is omitted
all groups the user is in are listed.
aclumask [[ users ] +bits | [ users ] -bits... ]
umask [[ users ] +bits | [ users ] -bits... ]
This specifies the access other users have to windows that will be created by the caller of the command.
Users may be no, one or a comma separated list of known usernames. If no users are specified, a list of
all currently known users is assumed. Bits is any combination of access control bits allowed defined
with the aclchg command. The special username ? predefines the access that not yet known users will be
granted to any window initially. The special username ?? predefines the access that not yet known users
are granted to any command. Rights of the special username nobody cannot be changed (see the su
command). `Umask' is a synonym to `aclumask'.
activity message
When any activity occurs in a background window that is being monitored, screen displays a notification
in the message line. The notification message can be re-defined by means of the activity command. Each
occurrence of `%' in message is replaced by the number of the window in which activity has occurred, and
each occurrence of `^G' is replaced by the definition for bell in your termcap (usually an audible bell).
The default message is
'Activity in window %n'
Note that monitoring is off for all windows by default, but can be altered by use of the monitor command
(C-a M).
allpartial [ on | off ]
If set to on, only the current cursor line is refreshed on window change. This affects all windows and
is useful for slow terminal lines. The previous setting of full/partial refresh for each window is
restored with allpartial off. This is a global flag that immediately takes effect on all windows
overriding the partial settings. It does not change the default redraw behavior of newly created windows.
altscreen [ on | off ]
If set to on, "alternate screen" support is enabled in virtual terminals, just like in xterm. Initial
setting is `off'.
at [identifier][#|*|%] command [args ... ]
Execute a command at other displays or windows as if it had been entered there. At changes the context
(the `current window' or `current display' 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. Permission is checked for initiator of the at command, not for
the owners of the affected display(s). Note that the '#' character works as a comment introducer when it
is preceded by whitespace. This can be escaped by prefixing a '\'. Permission is checked for the
initiator of the at command, not for the owners of the affected display(s).
Caveat: When matching against windows, the command is executed at least once per window. Commands that
change the internal arrangement of windows (like other) may be called again. In shared windows the
command will be repeated for each attached display. Beware, when issuing toggle commands like login!
Some commands (e.g. process) require that a display is associated with the target windows. These
commands may not work correctly under at looping over windows.
attrcolor attrib [attribute/color-modifier]
This command can be used to highlight attributes by changing the color of the text. If the attribute
attrib is in use, the specified attribute/color modifier is also applied. If no modifier is given, the
current one is deleted. See the STRING ESCAPES chapter for the syntax of the modifier. Screen understands
two pseudo-attributes, i stands for high-intensity foreground color and I for high-intensity background
color.
Examples:
attrcolor b "R"
Change the color to bright red if bold text is to be printed.
attrcolor u "-u b"
Use blue text instead of underline.
attrcolor b ".I"
Use bright colors for bold text. Most terminal emulators do this already.
attrcolor i "+b"
Make bright colored text also bold.
autodetach [ on | off ]
Sets whether screen will automatically detach upon hangup, which saves all your running programs until
they are resumed with a screen -r command. When turned off, a hangup signal will terminate screen and
all the processes it contains. Autodetach is on by default.
autonuke [ on | off ]
Sets whether a clear screen sequence should nuke all the output that has not been written to the
terminal. See also obuflimit.
backtick id lifespan autorefresh cmd args...
backtick id
Program the backtick command with the numerical id id. The output of such a command is used for
substitution of the %` string escape. The specified lifespan is the number of seconds the output is
considered valid. After this time, the command is run again if a corresponding string escape is
encountered. The autorefresh parameter triggers an automatic refresh for caption and hardstatus strings
after the specified number of seconds. Only the last line of output is used for substitution.
If both the lifespan and the autorefresh parameters are zero, the backtick program is expected to stay in
the background and generate output once in a while. In this case, the command is executed right away and
screen stores the last line of output. If a new line gets printed screen will automatically refresh the
hardstatus or the captions.
The second form of the command deletes the backtick command with the numerical id id.
bce [ on | off ]
Change background-color-erase setting. If bce is set to on, all characters cleared by an
erase/insert/scroll/clear operation will be displayed in the current background color. Otherwise the
default background color is used.
bell_msg [message]
When a bell character is sent to a background window, screen displays a notification in the message line.
The notification message can be re-defined by this command. Each occurrence of `%' in message is
replaced by the number of the window to which a bell has been sent, and each occurrence of `^G' is
replaced by the definition for bell in your termcap (usually an audible bell). The default message is
'Bell in window %n'
An empty message can be supplied to the bell_msg command to suppress output of a message line (bell_msg
""). Without parameter, the current message is shown.
bind [class] key [command [args]]
Bind a command to a key. By default, most of the commands provided by screen are bound to one or more
keys as indicated in the DEFAULT KEY BINDINGS section, e.g. the command to create a new window is bound
to C-c and c. The bind command can be used to redefine the key bindings and to define new bindings. The
key argument is either a single character, a two-character sequence of the form ^x (meaning C-x), a
backslash followed by an octal number (specifying the ASCII code of the character), or a backslash
followed by a second character, such as \^ or \\. The argument can also be quoted, if you like. If no
further argument is given, any previously established binding for this key is removed. The command
argument can be any command listed in this section.
If a command class is specified via the -c option, the key is bound for the specified class. Use the
command command to activate a class. Command classes can be used to create multiple command keys or
multi-character bindings.
Some examples:
bind ' ' windows
bind ^k
bind k
bind K kill
bind ^f screen telnet foobar
bind \033 screen -ln -t root -h 1000 9 su
would bind the space key to the command that displays a list of windows (so that the command usually
invoked by C-a C-w would also be available as C-a space). The next three lines remove the default kill
binding from C-a C-k and C-a k. C-a K is then bound to the kill command. Then it binds C-f to the
command create a window with a TELNET connection to foobar, and bind escape to the command that creates
an non-login window with a.k.a. root in slot #9, with a superuser shell and a scrollback buffer of 1000
lines.
bind -c demo1 0 select 10
bind -c demo1 1 select 11
bind -c demo1 2 select 12
bindkey "^B" command -c demo1
makes C-b 0 select window 10, C-b 1 window 11, etc.
bind -c demo2 0 select 10
bind -c demo2 1 select 11
bind -c demo2 2 select 12
bind - command -c demo2
makes C-a - 0 select window 10, C-a - 1 window 11, etc.
bindkey [-d] [-m] [-a] [[-k|-t] string [cmd-args]]
This command manages screen's input translation tables. Every entry in one of the tables tells screen how
to react if a certain sequence of characters is encountered. There are three tables: one that should
contain actions programmed by the user, one for the default actions used for terminal emulation and one
for screen's copy mode to do cursor movement. See section INPUT TRANSLATION for a list of default key
bindings.
If the -d option is given, bindkey modifies the default table, -m changes the copy mode table and with
neither option the user table is selected. The argument string is the sequence of characters to which an
action is bound. This can either be a fixed string or a termcap keyboard capability name (selectable with
the -k option).
Some keys on a VT100 terminal can send a different string if application mode is turned on (e.g the
cursor keys). Such keys have two entries in the translation table. You can select the application mode
entry by specifying the -a option.
The -t option tells screen not to do inter-character timing. One cannot turn off the timing if a termcap
capability is used.
Cmd can be any of screen's commands with an arbitrary number of args. If cmd is omitted the key-binding
is removed from the table.
Here are some examples of keyboard bindings:
bindkey -d
Show all of the default key bindings. The application mode entries are marked with [A].
bindkey -k k1 select 1
Make the "F1" key switch to window one.
bindkey -t foo stuff barfoo
Make "foo" an abbreviation of the word "barfoo". Timeout is disabled so that users can type slowly.
bindkey "\024" mapdefault
This key-binding makes ^T an escape character for key-bindings. If you did the above stuff barfoo
binding, you can enter the word foo by typing ^Tfoo. If you want to insert a ^T you have to press the key
twice (i.e., escape the escape binding).
bindkey -k F1 command
Make the F11 (not F1!) key an alternative screen escape (besides ^A).
break [duration]
Send a break signal for duration*0.25 seconds to this window. For non-Posix systems the time interval
may be rounded up to full seconds. Most useful if a character device is attached to the window rather
than a shell process (See also chapter WINDOW TYPES). The maximum duration of a break signal is limited
to 15 seconds.
blanker
Activate the screen blanker. First the screen is cleared. If no blanker program is defined, the cursor is
turned off, otherwise, the program is started and it's output is written to the screen. The screen
blanker is killed with the first keypress, the read key is discarded.
This command is normally used together with the idle command.
blankerprg [program-args]
Defines a blanker program. Disables the blanker program if an empty argument is given. Shows the
currently set blanker program if no arguments are given.
breaktype [tcsendbreak|TIOCSBRK|TCSBRK]
Choose one of the available methods of generating a break signal for terminal devices. This command
should affect the current window only. But it still behaves identical to defbreaktype. This will be
changed in the future. Calling breaktype with no parameter displays the break method for the current
window.
bufferfile [exchange-file]
Change the filename used for reading and writing with the paste buffer. If the optional argument to the
bufferfile command is omitted, the default setting (/tmp/screen-exchange) is reactivated. The following
example will paste the system's password file into the screen window (using the paste buffer, where a
copy remains):
C-a : bufferfile /etc/passwd
C-a < C-a ]
C-a : bufferfile
bumpleft
Swaps window with previous one on window list.
bumpright
Swaps window with next one on window list.
c1 [ on | off ]
Change c1 code processing. C1 on tells screen to treat the input characters between 128 and 159 as
control functions. Such an 8-bit code is normally the same as ESC followed by the corresponding 7-bit
code. The default setting is to process c1 codes and can be changed with the defc1 command. Users with
fonts that have usable characters in the c1 positions may want to turn this off.
caption [ top | bottom ] always|splitonly[string]
caption string [string]
This command controls the display of the window captions. Normally a caption is only used if more than
one window is shown on the display (split screen mode). But if the type is set to always screen shows a
caption even if only one window is displayed. The default is splitonly.
The second form changes the text used for the caption. You can use all escapes from the STRING ESCAPES
chapter. Screen uses a default of `%3n %t'.
You can mix both forms by providing a string as an additional argument.
You can have the caption displayed either at the top or bottom of the window. The default is bottom.
charset set
Change the current character set slot designation and charset mapping. The first four character of set
are treated as charset designators while the fifth and sixth character must be in range '0' to '3' and
set the GL/GR charset mapping. On every position a '.' may be used to indicate that the corresponding
charset/mapping should not be changed (set is padded to six characters internally by appending '.'
chars). New windows have "BBBB02" as default charset, unless a encoding command is active.
The current setting can be viewed with the info command.
chdir [directory]
Change the current directory of screen to the specified directory or, if called without an argument, to
your home directory (the value of the environment variable $HOME). All windows that are created by means
of the screen command from within .screenrc or by means of C-a : screen ... or C-a c use this as their
default directory. Without a chdir command, this would be the directory from which screen was invoked.
Hardcopy and log files are always written to the window's default directory, not the current directory of
the process running in the window. You can use this command multiple times in your .screenrc to start
various windows in different default directories, but the last chdir value will affect all the windows
you create interactively.
cjkwidth [ on | off ]
Treat ambiguous width characters as full/half width.
clear
Clears the current window and saves its image to the scrollback buffer.
collapse
Reorders window on window list, removing number gaps between them.
colon [prefix]
Allows you to enter .screenrc command lines. Useful for on-the-fly modification of key bindings, specific
window creation and changing settings. Note that the set keyword no longer exists! Usually commands
affect the current window rather than default settings for future windows. Change defaults with commands
starting with 'def...'.
If you consider this as the `Ex command mode' of screen, you may regard C-a esc (copy mode) as its `Vi
command mode'.
command [ -c class"]"
This command has the same effect as typing the screen escape character (^A). It is probably only useful
for key bindings. If the -c option is given, select the specified command class. See also bind and
bindkey.
compacthist [ on | off ]
This tells screen whether to suppress trailing blank lines when scrolling up text into the history
buffer.
console [ on | off ]
Grabs or un-grabs the machines console output to a window. Note: Only the owner of /dev/console can grab
the console output. This command is only available if the machine supports the ioctl TIOCCONS.
copy
Enter copy/scrollback mode. This allows you to copy text from the current window and its history into the
paste buffer. In this mode a vi-like `full screen editor' is active:
The editor's movement keys are:
────────────────────────────────────────────────────────────────
h, C-h, move the cursor left.
left arrow
────────────────────────────────────────────────────────────────
j, C-n, move the cursor down.
down arrow
────────────────────────────────────────────────────────────────
k, C-p, move the cursor up.
up arrow
────────────────────────────────────────────────────────────────
l ('el'), move the cursor right.
right arrow
────────────────────────────────────────────────────────────────
0 (zero) C-a move to the leftmost column.
────────────────────────────────────────────────────────────────
+ and - positions one line up and down.
────────────────────────────────────────────────────────────────
H, M and L move the cursor to the leftmost column of the
top, center or bottom line of the window.
────────────────────────────────────────────────────────────────
| moves to the specified absolute column.
────────────────────────────────────────────────────────────────
g or home moves to the beginning of the buffer.
────────────────────────────────────────────────────────────────
G or end moves to the specified absolute line (default:
end of buffer).
────────────────────────────────────────────────────────────────
% jumps to the specified percentage of the buffer.
────────────────────────────────────────────────────────────────
^ or $ move to the leftmost column, to the first or
last non-whitespace character on the line.
────────────────────────────────────────────────────────────────
w, b, and e move the cursor word by word.
────────────────────────────────────────────────────────────────
B, E move the cursor WORD by WORD (as in vi).
────────────────────────────────────────────────────────────────
f/F, t/T move the cursor forward/backward to the next
occurrence of the target. (eg, '3fy' will move
the cursor to the 3rd 'y' to the right.)
────────────────────────────────────────────────────────────────
; and , Repeat the last f/F/t/T command in the
same/opposite direction.
────────────────────────────────────────────────────────────────
C-e and C-y scroll the display up/down by one line while
preserving the cursor position.
────────────────────────────────────────────────────────────────
C-u and C-d scroll the display up/down by the specified
amount of lines while preserving the cursor
position. (Default: half screen-full).
────────────────────────────────────────────────────────────────
C-b and C-f scroll the display up/down a full screen.
────────────────────────────────────────────────────────────────
Note: Emacs style movement keys can be customized by a .screenrc command. (E.g. markkeys
"h=^B:l=^F:$=^E") There is no simple method for a full emacs-style keymap, as this involves multi-
character codes.
Some keys are defined to do mark and replace operations.
The copy range is specified by setting two marks. The text between these marks will be highlighted.
Press:
space or enter to set the first or second mark respectively. If mousetrack is set to `on', marks
can also be set using left mouse click.
Y and y used to mark one whole line or to mark from start of line.
W marks exactly one word.
Any of these commands can be prefixed with a repeat count number by pressing digits
0..9 which is taken as a repeat count.
Example: C-a C-[ H 10 j 5 Y will copy lines 11 to 15 into the paste buffer.
The following search keys are defined:
/ Vi-like search forward.
? Vi-like search backward.
C-a s Emacs style incremental search forward.
C-r Emacs style reverse i-search.
n Find next search pattern.
N Find previous search pattern.
There are however some keys that act differently than in vi. Vi does not allow one to yank rectangular
blocks of text, but screen does. Press: c or C to set the left or right margin respectively. If no repeat
count is given, both default to the current cursor position.
Example: Try this on a rather full text screen:
C-a [ M 20 l SPACE c 10 l 5 j C SPACE.
This moves one to the middle line of the screen, moves in 20 columns left, marks the beginning of the
paste buffer, sets the left column, moves 5 columns down, sets the right column, and then marks the end
of the paste buffer. Now try:
C-a [ M 20 l SPACE 10 l 5 j SPACE
and notice the difference in the amount of text copied.
J joins lines. It toggles between 4 modes: lines separated by a newline character (012), lines glued
seamless, lines separated by a single whitespace and comma separated lines. Note that you can prepend the
newline character with a carriage return character, by issuing a crlf on.
v or V is for all the vi users with :set numbers - it toggles the left margin between column 9 and 1.
Press
a before the final space key to toggle in append mode. Thus the contents of the paste buffer will not be
overwritten, but is appended to.
A toggles in append mode and sets a (second) mark.
> sets the (second) mark and writes the contents of the paste buffer to the screen-exchange file
(/tmp/screen-exchange per default) once copy-mode is finished.
This example demonstrates how to dump the whole scrollback buffer to that file: C-A [ g SPACE G $ >.
C-g gives information about the current line and column.
x or o exchanges the first mark and the current cursor position. You can use this to adjust an already
placed mark.
C-l ('el') will redraw the screen.
@ does nothing. Does not even exit copy mode.
All keys not described here exit copy mode.
copy_reg [key]
No longer exists, use readreg instead.
crlf [ on | off ]
This affects the copying of text regions with the `C-a [' command. If it is set to `on', lines will be
separated by the two character sequence `CR' - `LF'. Otherwise (default) only `LF' is used. When no
parameter is given, the state is toggled.
debug [ on | off ]
Turns runtime debugging on or off. If screen has been compiled with option -DDEBUG debugging available
and is turned on per default. Note that this command only affects debugging output from the main SCREEN
process correctly. Debug output from attacher processes can only be turned off once and forever.
defc1 [ on | off ]
Same as the c1 command except that the default setting for new windows is changed. Initial setting is
`on'.
defautonuke [ on | off ]
Same as the autonuke command except that the default setting for new displays is changed. Initial setting
is `off'. Note that you can use the special `AN' terminal capability if you want to have a dependency on
the terminal type.
defbce [ on | off ]
Same as the bce command except that the default setting for new windows is changed. Initial setting is
`off'.
defbreaktype [tcsendbreak|TIOCSBRK|TCSBRK]
Choose one of the available methods of generating a break signal for terminal devices. The preferred
methods are tcsendbreak and TIOCSBRK. The third, TCSBRK, blocks the complete screen session for the
duration of the break, but it may be the only way to generate long breaks. Tcsendbreak and TIOCSBRK may
or may not produce long breaks with spikes (e.g. 4 per second). This is not only system-dependent, this
also differs between serial board drivers. Calling defbreaktype with no parameter displays the current
setting.
defcharset [set]
Like the charset command except that the default setting for new windows is changed. Shows current
default if called without argument.
defdynamictitle [ on | off ]
Set default behaviour for new windows regarding if screen should change window title when seeing proper
escape sequence. See also "TITLES (naming windows)" section.
defescape xy
Set the default command characters. This is equivalent to the escape except that it is useful multiuser
sessions only. In a multiuser session escape changes the command character of the calling user, where
defescape changes the default command characters for users that will be added later.
defflow [ on | off | auto [ interrupt ]]
Same as the flow command except that the default setting for new windows is changed. Initial setting is
`auto'. Specifying defflow auto interrupt is the same as the command-line options -fa and -i.
defgr [ on | off ]
Same as the gr command except that the default setting for new windows is changed. Initial setting is
`off'.
defhstatus [status]
The hardstatus line that all new windows will get is set to status. This command is useful to make the
hardstatus of every window display the window number or title or the like. Status may contain the same
directives as in the window messages, but the directive escape character is '^E' (octal 005) instead of
'%'. This was done to make a misinterpretation of program generated hardstatus lines impossible. If the
parameter status is omitted, the current default string is displayed. Per default the hardstatus line of
new windows is empty.
defencoding enc
Same as the encoding command except that the default setting for new windows is changed. Initial setting
is the encoding taken from the terminal.
deflog [ on | off ]
Same as the log command except that the default setting for new windows is changed. Initial setting is
`off'.
deflogin [ on | off ]
Same as the login command except that the default setting for new windows is changed. This is initialized
with `on' as distributed (see config.h.in).
defmode mode
The mode of each newly allocated pseudo-tty is set to mode. Mode is an octal number. When no defmode
command is given, mode 0622 is used.
defmonitor [ on | off]
Same as the monitor command except that the default setting for new windows is changed. Initial setting
is `off'.
defmousetrack [ on | off ]
Same as the mousetrack command except that the default setting for new windows is changed. Initial
setting is `off'.
defnonblock [ on | off | numsecs]
Same as the nonblock command except that the default setting for displays is changed. Initial setting is
`off'.
defobuflimit limit
Same as the obuflimit command except that the default setting for new displays is changed. Initial
setting is 256 bytes. Note that you can use the special 'OL' terminal capability if you want to have a
dependency on the terminal type.
defscrollback num
Same as the scrollback command except that the default setting for new windows is changed. Initial
setting is 100.
defshell command
Synonym to the shell .screenrc command. See there.
defsilence [ on | off ]
Same as the silence command except that the default setting for new windows is changed. Initial setting
is `off'.
defslowpaste msec
Same as the slowpaste command except that the default setting for new windows is changed. Initial setting
is 0 milliseconds, meaning `off'.
defutf8 [ on | off ]
Same as the utf8 command except that the default setting for new windows is changed. Initial setting is
`on' if screen was started with -U, otherwise `off'.
defwrap [ on | off ]
Same as the wrap command except that the default setting for new windows is changed. Initially line-wrap
is on and can be toggled with the wrap command (C-a r) or by means of "C-a : wrap on|off".
defwritelock [ on | off | auto ]
Same as the writelock command except that the default setting for new windows is changed. Initially
writelocks will off.
detach [-h]
Detach the screen session (disconnect it from the terminal and put it into the background). This returns
you to the shell where you invoked screen. A detached screen can be resumed by invoking screen with the
-r option (see also section COMMAND-LINE OPTIONS). The -h option tells screen to immediately close the
connection to the terminal (hangup).
dinfo
Show what screen thinks about your terminal. Useful if you want to know why features like color or the
alternate charset don't work.
displays
Shows a tabular listing of all currently connected user front-ends (displays). This is most useful for
multiuser sessions. The following keys can be used in displays list:
──────────────────────────────────────────────────────────────
k, C-p, or up Move up one line.
──────────────────────────────────────────────────────────────
j, C-n, or down Move down one line.
──────────────────────────────────────────────────────────────
C-a or home Move to the first line.
──────────────────────────────────────────────────────────────
C-e or end Move to the last line.
──────────────────────────────────────────────────────────────
C-u or C-d Move one half page up or down.
──────────────────────────────────────────────────────────────
C-b or C-f Move one full page up or down.
──────────────────────────────────────────────────────────────
mouseclick Move to the selected line. Available
when mousetrack is set to on.
──────────────────────────────────────────────────────────────
space Refresh the list
──────────────────────────────────────────────────────────────
d Detach that display
──────────────────────────────────────────────────────────────
D Power detach that display
──────────────────────────────────────────────────────────────
C-g, enter, or escape Exit the list
──────────────────────────────────────────────────────────────
The following is an example of what displays could look like:
xterm 80x42 jnweiger@/dev/ttyp4 0(m11) &rWx
facit 80x24 mlschroe@/dev/ttyhf nb 11(tcsh) rwx
xterm 80x42 jnhollma@/dev/ttyp5 0(m11) &R.x
(A) (B) (C) (D) (E) (F)(G) (H)(I)
The legend is as follows:
(A) The terminal type known by screen for this display.
(B) Displays geometry as width x height.
(C) Username who is logged in at the display.
(D) Device name of the display or the attached device
(E) Display is in blocking or nonblocking mode. The available modes are "nb", "NB", "Z<", "Z>",
and "BL".
(F) Number of the window
(G) Name/title of window
(H) Whether the window is shared
(I) Window permissions. Made up of three characters.
┌─────────────────────────────────────────────────────────┐
│ Window permissions indicators │
├──────────────────┬──────────────────┬───────────────────┤
│ 1st character │ 2nd character │ 3rd character │
├─────┬────────────┼─────┬────────────┼─────┬─────────────┤
│ - │no read │ - │no write │ - │no execute │
├─────┼────────────┼─────┼────────────┼─────┼─────────────┤
│ r │read │ w │write │ x │execute │
├─────┼────────────┼─────┼────────────┼─────┼─────────────┤
│ │ │ W │own wlock │ │ │
├─────┴────────────┴─────┴────────────┴─────┴─────────────┤
│ Indicators of permissions suppressed by a foreign wlock │
├─────┬────────────┬─────┬────────────┬─────┬─────────────┤
│ R │read only │ . │no write │ │ │
└─────┴────────────┴─────┴────────────┴─────┴─────────────┘
displays needs a region size of at least 10 characters wide and 5 characters high in order to
display.
digraph [preset[unicode-value]]
This command prompts the user for a digraph sequence. The next two characters typed are looked up in a
builtin table and the resulting character is inserted in the input stream. For example, if the user
enters 'a"', an a-umlaut will be inserted. If the first character entered is a 0 (zero), screen will
treat the following characters (up to three) as an octal number instead. The optional argument preset is
treated as user input, thus one can create an umlaut key. For example the command "bindkey ^K digraph
'"'" enables the user to generate an a-umlaut by typing CTRL-K a. When a non-zero unicode-value is
specified, a new digraph is created with the specified preset. The digraph is unset if a zero value is
provided for the unicode-value.
dumptermcap
Write the termcap entry for the virtual terminal optimized for the currently active window to the file
.termcap in the user's $HOME/.screen directory (or wherever screen stores its sockets. See the FILES
section below). This termcap entry is identical to the value of the environment variable $TERMCAP that
is set up by screen for each window. For terminfo based systems you will need to run a converter like
captoinfo and then compile the entry with tic.
dynamictitle [ on | off ]
Change behaviour for windows regarding if screen should change window title when seeing proper escape
sequence. See also "TITLES (naming windows)" section.
echo [-n] message
The echo command may be used to annoy screen users with a 'message of the day'. Typically installed in a
global /etc/screenrc. The option -n may be used to suppress the line feed. See also sleep. Echo is
also useful for online checking of environment variables.
encoding enc [enc]
Tell screen how to interpret the input/output. The first argument sets the encoding of the current
window. Each window can emulate a different encoding. The optional second parameter overwrites the
encoding of the connected terminal. It should never be needed as screen uses the locale setting to detect
the encoding. There is also a way to select a terminal encoding depending on the terminal type by using
the KJ termcap entry.
Supported encodings are eucJP, SJIS, eucKR, eucCN, Big5, GBK, KOI8-R, KOI8-U, CP1251, UTF-8, ISO8859-2,
ISO8859-3, ISO8859-4, ISO8859-5, ISO8859-6, ISO8859-7, ISO8859-8, ISO8859-9, ISO8859-10, ISO8859-15, jis.
See also defencoding, which changes the default setting of a new window.
escape xy
Set the command character to x and the character generating a literal command character (by triggering
the meta command) to y (similar to the -e option). Each argument is either a single character, a two-
character sequence of the form ^x (meaning C-x), a backslash followed by an octal number (specifying the
ASCII code of the character), or a backslash followed by a second character, such as \^ or \\. The
default is ^Aa.
eval command1[command2 ...]
Parses and executes each argument as separate command.
exec [[fdpat]newcommand [args ...]]
Run a unix subprocess (specified by an executable path newcommand and its optional arguments) in the
current window. The flow of data between newcommands stdin/stdout/stderr, the process originally started
in the window (let us call it "application-process") and screen itself (window) is controlled by the file
descriptor pattern fdpat. This pattern is basically a three character sequence representing stdin,
stdout and stderr of newcommand. A dot (.) connects the file descriptor to screen. An exclamation mark
(!) causes the file descriptor to be connected to the application-process. A colon (:) combines both.
User input will go to newcommand unless newcommand receives the application-process' output (fdpats first
character is `!' or `:') or a pipe symbol (|) is added (as a fourth character) to the end of fdpat.
Invoking `exec' without arguments shows name and arguments of the currently running subprocess in this
window. Only one subprocess a time can be running in each window.
When a subprocess is running the `kill' command will affect it instead of the windows process.
Refer to the postscript file `doc/fdpat.ps' for a confusing illustration of all 21 possible combinations.
Each drawing shows the digits 2,1,0 representing the three file descriptors of newcommand. The box marked
`W' is the usual pty that has the application-process on its slave side. The box marked `P' is the
secondary pty that now has screen at its master side.
Abbreviations: Whitespace between the word `exec' and fdpat and the command can be omitted. Trailing dots
and a fdpat consisting only of dots can be omitted. A simple `|' is synonymous for the pattern `!..|';
the word exec can be omitted here and can always be replaced by `!'.
Examples:
exec ... /bin/sh
exec /bin/sh
!/bin/sh
Creates another shell in the same window, while the original shell is still running. Output
of both shells is displayed and user input is sent to the new /bin/sh.
exec !.. stty 19200
exec ! stty 19200
!!stty 19200
Set the speed of the window's tty. If your stty command operates on stdout, then add
another `!'.
exec !..| less
|less
This adds a pager to the window output. The special character `|' is needed to give the
user control over the pager although it gets its input from the window's process. This
works, because less listens on stderr (a behavior that screen would not expect without the
`|') when its stdin is not a tty. Less versions newer than 177 fail miserably here; good
old pg still works.
!:sed -n s/.*Error.*/\007/p
Sends window output to both, the user and the sed command. The sed inserts an additional
bell character (oct. 007) to the window output seen by screen. This will cause "Bell in
window x" messages, whenever the string "Error" appears in the window.
fit
Change the window size to the size of the current region. This command is needed because screen doesn't
adapt the window size automatically if the window is displayed more than once.
flow [ on | off | auto]
Sets the flow-control mode for this window. Without parameters it cycles the current window's flow-
control setting from "automatic" to "on" to "off". See the discussion on FLOW-CONTROL later on in this
document for full details and note, that this is subject to change in future releases. Default is set by
`defflow'.
focus [ next | prev | up | down | left | right | top | bottom ]
Move the input focus to the next region. This is done in a cyclic way so that the top left region is
selected after the bottom right one. If no option is given it defaults to `next'. The next region to be
selected is determined by how the regions are layered. Normally, the next region in the same layer would
be selected. However, if that next region contains one or more layers, the first region in the highest
layer is selected first. If you are at the last region of the current layer, `next' will move the focus
to the next region in the lower layer (if there is a lower layer). `Prev' cycles in the opposite order.
See split for more information about layers.
The rest of the options (`up', `down', `left', `right', `top', and `bottom') are more indifferent to
layers. The option `up' will move the focus upward to the region that is touching the upper left corner
of the current region. `Down' will move downward to the region that is touching the lower left corner of
the current region. The option `left' will move the focus leftward to the region that is touching the
upper left corner of the current region, while `right' will move rightward to the region that is touching
the upper right corner of the current region. Moving left from a left most region or moving right from a
right most region will result in no action.
The option `top' will move the focus to the very first region in the upper list corner of the screen, and
`bottom' will move to the region in the bottom right corner of the screen. Moving up from a top most
region or moving down from a bottom most region will result in no action.
Useful bindings are (h, j, k, and l as in vi)
bind h focus left
bind j focus down
bind k focus up
bind l focus right
bind t focus top
bind b focus bottom
Note that k is traditionally bound to the kill command.
focusminsize [ ( width|max|_ ) ( height|max|_ ) ]
This forces any currently selected region to be automatically resized at least a certain width and
height. All other surrounding regions will be resized in order to accommodate. This constraint follows
every time the focus command is used. The resize command can be used to increase either dimension of a
region, but never below what is set with focusminsize. The underscore `_' is a synonym for max. Setting a
width and height of `0 0' (zero zero) will undo any constraints and allow for manual resizing. Without
any parameters, the minimum width and height is shown.
gr [ on | off ]
Turn GR charset switching on/off. Whenever screen sees an input character with the 8th bit set, it will
use the charset stored in the GR slot and print the character with the 8th bit stripped. The default (see
also defgr) is not to process GR switching because otherwise the ISO88591 charset would not work.
group [grouptitle]
Change or show the group the current window belongs to. Windows can be moved around between different
groups by specifying the name of the destination group. Without specifying a group, the title of the
current group is displayed.
hardcopy [-h] [file]
Writes out the currently displayed image to the file file, or, if no filename is specified, to hardcopy.n
in the default directory, where n is the number of the current window. This either appends or overwrites
the file if it exists. See below. If the option -h is specified, dump also the contents of the
scrollback buffer.
hardcopy_append [ on | off ]
If set to "on", screen will append to the "hardcopy.n" files created by the command C-a h, otherwise
these files are overwritten each time. Default is `off'.
hardcopydir directory
Defines a directory where hardcopy files will be placed. If unset, hardcopys are dumped in screen's
current working directory.
hardstatus [ on | off ]
hardstatus [ always ] firstline | lastline | message | ignore [ string ]
hardstatus string [ string ]
This command configures the use and emulation of the terminal's hardstatus line. The first form toggles
whether screen will use the hardware status line to display messages. If the flag is set to `off', these
messages are overlaid in reverse video mode at the display line. The default setting is `on'.
The second form tells screen what to do if the terminal doesn't have a hardstatus line (i.e. the
termcap/terminfo capabilities "hs", "ts", "fs" and "ds" are not set). When firstline/lastline is used,
screen will reserve the first/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 (e.g., alwayslastline), screen will use the type even if the terminal supports a hardstatus.
The third form specifies the contents of the hardstatus line. '%h' is used as default string, i.e., the
stored hardstatus of the current window (settable via ESC]0;<string>^G or ESC_<string>ESC\) is displayed.
You can customize this to any string you like including the escapes from the STRING ESCAPES chapter. If
you leave out the argument string, the current string is displayed.
You can mix the second and third form by providing the string as additional argument.
height [-w|-d] [lines [cols]]
Set the display height to a specified number of lines. When no argument is given it toggles between 24
and 42 lines display. You can also specify a width if you want to change both values. The -w option
tells screen to leave the display size unchanged and just set the window size, -d vice versa.
help[class]
Not really a online help, but displays a help screen showing you all the key bindings. The first pages
list all the internal commands followed by their current bindings. Subsequent pages will display the
custom commands, one command per key. Press space when you're done reading each page, or return to exit
early. All other characters are ignored. If the -c option is given, display all bound commands for the
specified command class. See also DEFAULT KEY BINDINGS section.
history
Usually users work with a shell that allows easy access to previous commands. For example csh has the
command !! to repeat the last command executed. Screen allows you to have a primitive way of re-calling
the command that started ...: You just type the first letter of that command, then hit `C-a {' and screen
tries to find a previous line that matches with the `prompt character' to the left of the cursor. This
line is pasted into this window's input queue. Thus you have a crude command history (made up by the
visible window and its scrollback buffer).
hstatus status
Change the window's hardstatus line to the string status.
idle [timeout[cmd-args]]
Sets a command that is run after the specified number of seconds inactivity is reached. This command will
normally be the blanker command to create a screen blanker, but it can be any screen command. If no
command is specified, only the timeout is set. A timeout of zero (or the special timeout off) disables
the timer. If no arguments are given, the current settings are displayed.
ignorecase [ on | off ]
Tell screen to ignore the case of characters in searches. Default is `off'. Without any options, the
state of ignorecase is toggled.
info
Uses the message line to display some information about the current window: the cursor position in the
form (column,row) starting with (1,1), the terminal width and height plus the size of the scrollback
buffer in lines, like in (80,24)+50, the current state of window XON/XOFF flow control is shown like this
(See also section FLOW CONTROL):
┌──────────┬──────────────────────────────────────────────────────────┐
│ +flow │ automatic flow control, currently on. │
├──────────┼──────────────────────────────────────────────────────────┤
│ -flow │ automatic flow control, currently off. │
├──────────┼──────────────────────────────────────────────────────────┤
│ +(+)flow │ flow control enabled. Agrees with automatic control. │
├──────────┼──────────────────────────────────────────────────────────┤
│ -(+)flow │ flow control disabled. Disagrees with automatic control. │
├──────────┼──────────────────────────────────────────────────────────┤
│ +(-)flow │ flow control enabled. Disagrees with automatic control. │
├──────────┼──────────────────────────────────────────────────────────┤
│ -(-)flow │ flow control disabled. Agrees with automatic control. │
└──────────┴──────────────────────────────────────────────────────────┘
The current line wrap setting (`+wrap' indicates enabled, `-wrap' not) is also shown. The flags `ins',
`org', `app', `log', `mon' or `nored' are displayed when the window is in insert mode, origin mode,
application-keypad mode, has output logging, activity monitoring or partial redraw enabled.
The currently active character set (G0, G1, G2, or G3) and in square brackets the terminal character sets
that are currently designated as G0 through G3 is shown. If the window is in UTF-8 mode, the string UTF-8
is shown instead.
Additional modes depending on the type of the window are displayed at the end of the status line (See
also chapter WINDOW TYPES).
If the state machine of the terminal emulator is in a non-default state, the info line is started with a
string identifying the current state.
For system information use the time command.
ins_reg [key]
No longer exists, use paste instead.
kill
Kill current window.
If there is an `exec' command running then it is killed. Otherwise the process (shell) running in the
window receives a HANGUP condition, the window structure is removed and screen (your display) switches to
another window. When the last window is destroyed, screen exits. After a kill screen switches to the
previously displayed window.
Note: Emacs users should keep this command in mind, when killing a line. It is recommended not to use C-
a as the screen escape key or to rebind kill to C-a K.
lastmsg
Redisplay the last contents of the message/status line. Useful if you're typing when a message appears,
because the message goes away when you press a key (unless your terminal has a hardware status line).
Refer to the commands msgwait and msgminwait for fine tuning.
layout new [title]
Create a new layout. The screen will change to one whole region and be switched to the blank window. From
here, you build the regions and the windows they show as you desire. The new layout will be numbered with
the smallest available integer, starting with zero. You can optionally give a title to your new layout.
Otherwise, it will have a default title of layout. You can always change the title later by using the
command layout title.
layout remove [n|title]
Remove, or in other words, delete the specified layout. Either the number or the title can be specified.
Without either specification, screen will remove the current layout.
Removing a layout does not affect your set windows or regions.
layout next
Switch to the next layout available
layout prev
Switch to the previous layout available
layout select [n|title]
Select the desired layout. Either the number or the title can be specified. Without either specification,
screen will prompt and ask which screen is desired. To see which layouts are available, use the layout
show command.
layout show
List on the message line the number(s) and title(s) of the available layout(s). The current layout is
flagged.
layout title [title]
Change or display the title of the current layout. A string given will be used to name the layout.
Without any options, the current title and number is displayed on the message line.
layout number [n]
Change or display the number of the current layout. An integer given will be used to number the layout.
Without any options, the current number and title is displayed on the message line.
layout attach [title|:last]
Change or display which layout to reattach back to. The default is :last, which tells screen to reattach
back to the last used layout just before detachment. By supplying a title, You can instruct screen to
reattach to a particular layout regardless which one was used at the time of detachment. Without any
options, the layout to reattach to will be shown in the message line.
layout save [n|title]
Remember the current arrangement of regions. When used, screen will remember the arrangement of
vertically and horizontally split regions. This arrangement is restored when a screen session is
reattached or switched back from a different layout. If the session ends or the screen process dies, the
layout arrangements are lost. The layout dump command should help in this situation. If a number or title
is supplied, screen will remember the arrangement of that particular layout. Without any options, screen
will remember the current layout.
Saving your regions can be done automatically by using the layout autosave command.
layout autosave [ on | off]
Change or display the status of automatically saving layouts. The default is on, meaning when screen is
detached or changed to a different layout, the arrangement of regions and windows will be remembered at
the time of change and restored upon return. If autosave is set to off, that arrangement will only be
restored to either to the last manual save, using layout save, or to when the layout was first created,
to a single region with a single window. Without either an on or off, the current status is displayed on
the message line.
layout dump [filename]
Write to a file the order of splits made in the current layout. This is useful to recreate the order of
your regions used in your current layout. Only the current layout is recorded. While the order of the
regions are recorded, the sizes of those regions and which windows correspond to which regions are not.
If no filename is specified, the default is layout-dump, saved in the directory that the screen process
was started in. If the file already exists, layout dump will append to that file. As an example:
C-a : layout dump /home/user/.screenrc
will save or append the layout to the user's .screenrc file.
license
Display the disclaimer page. This is done whenever screen is started without options, which should be
often enough. See also the startup_message command.
lockscreen
Lock this display. Call a screenlock program. Screen does not accept any command keys until this
program terminates. Meanwhile processes in the windows may continue, as the windows are in the `detached'
state. The screenlock program may be changed through the environment variable $LOCKPRG (which must be set
in the shell from which screen is started) and is executed with the user's uid and gid.
Warning: When you leave other shells unlocked and you have no password set on screen, the lock is void:
One could easily re-attach from an unlocked shell. This feature should rather be called `lockterminal'.
log [ on | off ]
Start/stop writing output of the current window to a file screenlog.n in the window's default directory,
where n is the number of the current window. This filename can be changed with the `logfile' command. If
no parameter is given, the state of logging is toggled. The session log is appended to the previous
contents of the file if it already exists. The current contents and the contents of the scrollback
history are not included in the session log. Default is `off'.
logfile filename
logfile flush secs
Defines the name the log files will get. The default is screenlog.%n. The second form changes the number
of seconds screen will wait before flushing the logfile buffer to the file-system. The default value is
10 seconds.
login [ on | off ]
Adds or removes the entry in the utmp database file for the current window. This controls if the window
is `logged in'. When no parameter is given, the login state of the window is toggled. Additionally to
that toggle, it is convenient having a `log in' and a `log out' key. E.g. `bind I login on' and `bind O
login off' will map these keys to be C-a I and C-a O. The default setting (in config.h.in) should be on
for a screen that runs under suid-root. Use the deflogin command to change the default login state for
new windows. Both commands are only present when screen has been compiled with utmp support.
logtstamp [on|off]
logtstamp after [secs]
logtstamp string
[string]
This command controls logfile time-stamp mechanism of screen. If time-stamps are turned on, screen adds
a string containing the current time to the logfile after two minutes of inactivity. When output
continues and more than another two minutes have passed, a second time-stamp is added to document the
restart of the output. You can change this timeout with the second form of the command. The third form is
used for customizing the time-stamp string (`-- %n:%t -- time-stamp -- %M/%d/%y %c:%s --\n' by default).
mapdefault
Tell screen that the next input character should only be looked up in the default bindkey table. See also
bindkey.
mapnotnext
Like mapdefault, but don't even look in the default bindkey table.
maptimeout [timeout]
Set the inter-character timer for input sequence detection to a timeout of timeout ms. The default
timeout is 300ms. Maptimeout with no arguments shows the current setting. See also bindkey.
markkeys string
This is a method of changing the keymap used for copy/history mode. The string is made up of
oldchar=newchar pairs which are separated by `:'. Example: The string B=^B:F=^F will change the keys `C-
b' and `C-f' to the vi style binding (scroll up/down fill page). This happens to be the default binding
for `B' and `F'. The command markkeys h=^B:l=^F:$=^E would set the mode for an emacs-style binding. If
your terminal sends characters, that cause you to abort copy mode, then this command may help by binding
these characters to do nothing. The no-op character is `@' and is used like this: markkeys @=L=H if you
do not want to use the `H' or `L' commands any longer. As shown in this example, multiple keys can be
assigned to one function in a single statement.
maxwin num
Set the maximum window number screen will create. Doesn't affect already existing windows. The number can
be increased only when there are no existing windows.
meta
Insert the command character (C-a) in the current window's input stream.
monitor [ on | off ]
Toggles activity monitoring of windows. When monitoring is turned on and an affected window is switched
into the background, you will receive the 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.
mousetrack [ on | off ]
This command determines whether screen will watch for mouse clicks. When this command is enabled, regions
that have been split in various ways can be selected by pointing to them with a mouse and left-clicking
them. Without specifying on or off, the current state is displayed. The default state is determined by
the defmousetrack command.
msgminwait sec
Defines the time screen delays a new message when one message is currently displayed. The default is 1
second.
msgwait sec
Defines the time a message is displayed if screen is not disturbed by other activity. The default is 5
seconds.
multiuser [ on | off ]
Switch between singleuser and multiuser mode. Standard screen operation is singleuser. In multiuser mode
the commands `acladd', `aclchg', `aclgrp' and `acldel' can be used to enable (and disable) other users
accessing this screen session.
nethack [ on | off ]
Changes the kind of error messages used by screen. When you are familiar with the game nethack, you may
enjoy the nethack-style messages which will often blur the facts a little, but are much funnier to read.
Anyway, standard messages often tend to be unclear as well.
This option is only available if screen was compiled with the NETHACK flag defined. The default setting
is then determined by the presence of the environment variable $NETHACKOPTIONS and the file ~/.nethackrc
- if either one is present, the default is on.
next
Switch to the next window. This command can be used repeatedly to cycle through the list of windows.
nonblock [ on | off | numsecs ]
Tell screen how to deal with user interfaces (displays) that cease to accept output. This can happen if a
user presses ^S or a TCP/modem connection gets cut but no hangup is received. If nonblock is off (this is
the default) screen waits until the display restarts to accept the output. If nonblock is on, screen
waits until the timeout is reached (on is treated as 1s). If the display still doesn't receive
characters, screen will consider it blocked and stop sending characters to it. If at some time it
restarts to accept characters, screen will unblock the display and redisplay the updated window contents.
number [[+|-]n]
Change the current window's number. If the given number n is already used by another window, both windows
exchange their numbers. If no argument is specified, the current window number (and title) is shown.
Using `+' or `-' will change the window's number by the relative amount specified.
obuflimit [limit]
If the output buffer contains more bytes than the specified limit, no more data will be read from the
windows. The default value is 256. If you have a fast display (like xterm), you can set it to some higher
value. If no argument is specified, the current setting is displayed.
only
Kill all regions but the current one.
other
Switch to the window displayed previously. If this window does no longer exist, other has the same effect
as next.
partial [ on | off ]
Defines whether the display should be refreshed (as with redisplay) after switching to the current
window. This command only affects the current window. To immediately affect all windows use the
allpartial command. Default is `off', of course. This default is fixed, as there is currently no
defpartial command.
password [crypted_pw]
Present a crypted password in your .screenrc file and screen will ask for it, whenever someone attempts
to resume a detached. This is useful if you have privileged programs running under screen and you want
to protect your session from reattach attempts by another user masquerading as your uid (i.e. any
superuser.) If no crypted password is specified, screen prompts twice for typing a password and places
its encryption in the paste buffer. Default is `none', this disables password checking.
paste [registers [dest_reg]]
Write the (concatenated) contents of the specified registers to the stdin queue of the current window.
The register '.' is treated as the paste buffer. If no parameter is given the user is prompted for a
single register to paste. The paste buffer can be filled with the copy, history and readbuf commands.
Other registers can be filled with the register, readreg and paste commands. If paste is called with a
second argument, the contents of the specified registers is pasted into the named destination register
rather than the window. If '.' is used as the second argument, the displays paste buffer is the
destination. Note, that paste uses a wide variety of resources: Whenever a second argument is specified
no current window is needed. When the source specification only contains registers (not the paste buffer)
then there need not be a current display (terminal attached), as the registers are a global resource. The
paste buffer exists once for every user.
pastefont [ on | off ]
Tell screen to include font information in the paste buffer. The default is not to do so. This command is
especially useful for multi character fonts like kanji.
pow_break
Reopen the window's terminal line and send a break condition. See `break'.
pow_detach
Power detach. Mainly the same as detach, but also sends a HANGUP signal to the parent process of screen.
CAUTION: This will result in a logout, when screen was started from your login-shell.
pow_detach_msg [message]
The message specified here is output whenever a `Power detach' was performed. It may be used as a
replacement for a logout message or to reset baud rate, etc. Without parameter, the current message is
shown.
prev
Switch to the window with the next lower number. This command can be used repeatedly to cycle through
the list of windows.
printcmd [cmd]
If cmd is not an empty string, screen will not use the terminal capabilities po/pf if it detects an ansi
print sequence ESC [ 5 i, but pipe the output into cmd. This should normally be a command like lpr or
printcmd without a command displays the current setting. The ansi sequence ESC [ 4 i ends printing and
closes the pipe.
Warning: Be careful with this command! If other user have write access to your terminal, they will be
able to fire off print commands.
process [key]
Stuff the contents of the specified register into screen's input queue. If no argument is given you are
prompted for a register name. The text is parsed as if it had been typed in from the user's keyboard.
This command can be used to bind multiple actions to a single key.
quit
Kill all windows and terminate screen. Note that on VT100-style terminals the keys C-4 and C-\ are
identical. This makes the default bindings dangerous: Be careful not to type C-a C-4 when selecting
window no. 4. Use the empty bind command (as in bind '^\') to remove a key binding.
readbuf [encoding] [filename]
Reads the contents of the specified file into the paste buffer. You can tell screen the encoding of the
file via the -e option. If no file is specified, the screen-exchange filename is used. See also
bufferfile command.
readreg [encoding] [register [filename]]
Does one of two things, dependent on number of arguments: with zero or one arguments it duplicates the
paste buffer contents into the register specified or entered at the prompt. With two arguments it reads
the contents of the named file into the register, just as readbuf reads the screen-exchange file into the
paste buffer. You can tell screen the encoding of the file via the -e option. The following example
will paste the system's password file into the screen window (using register p, where a copy remains):
C-a : readreg p /etc/passwd
C-a : paste p
redisplay
Redisplay the current window. Needed to get a full redisplay when in partial redraw mode.
register [-eencoding]key-string
Save the specified string to the register key. The encoding of the string can be specified via the -e
option. See also the paste command.
remove
Kill the current region. This is a no-op if there is only one region.
removebuf
Unlinks the screen-exchange file used by the commands writebuf and readbuf.
rendition [ bell | monitor | silence | so ] attr [ color ]
Change the way screen renders the titles of windows that have monitor or bell flags set in caption or
hardstatus or windowlist. See the STRING ESCAPES chapter for the syntax of the modifiers. The default
for monitor is currently =b (bold, active colors), for bell =ub (underline, bold and active colors),
and =u for silence.
reset
Reset the virtual terminal to its power-on values. Useful when strange settings (like scroll regions or
graphics character set) are left over from an application.
resize [-h|-v|-b|-l|-p] [[+|-] n[%] |=|max|min|_|0]
Resize the current region. The space will be removed from or added to the surrounding regions depending
on the order of the splits. The available options for resizing are `-h'(horizontal), `-v'(vertical),
`-b'(both), `-l'(local to layer), and `-p'(perpendicular). Horizontal resizes will add or remove width to
a region, vertical will add or remove height, and both will add or remove size from both dimensions.
Local and perpendicular are similar to horizontal and vertical, but they take in account of how a region
was split. If a region's last split was horizontal, a local resize will work like a vertical resize. If
a region's last split was vertical, a local resize will work like a horizontal resize. Perpendicular
resizes work in opposite of local resizes. If no option is specified, local is the default.
The amount of lines to add or remove can be expressed a couple of different ways. By specifying a number
n by itself will resize the region by that absolute amount. You can specify a relative amount by
prefixing a plus `+' or minus `-' to the amount, such as adding +n lines or removing -n lines. Resizing
can also be expressed as an absolute or relative percentage by postfixing a percent sign `%'. Using zero
`0' is a synonym for `min' and using an underscore `_' is a synonym for `max'.
Some examples are:
resize +N
increase current region by N
resize -N
decrease current region by N
resize N
set current region to N
resize 20%
set current region to 20% of original size
resize +20%
increase current region by 20%
resize -b =
make all windows equally
resize max
maximize current region
resize min
minimize current region
Without any arguments, screen will prompt for how you would like to resize the current region.
See focusminsize if you want to restrict the minimum size a region can have.
screen [-opts] [n] [cmd [args]|//group]
Establish a new window. The flow-control options (-f, -fn and -fa), title (a.k.a.) option (-t), login
options (-l and -ln) , terminal type option (-T <term>), the all-capability-flag (-a) and scrollback
option (-h <num>) may be specified with each command. The option (-M) turns monitoring on for this
window. The option (-L) turns output logging on for this window. If an optional number n in the range
0..MAXWIN-1 is given, the window number n is assigned to the newly created window (or, if this number is
already in-use, the next available number). If a command is specified after screen, this command (with
the given arguments) is started in the window; otherwise, a shell is created. If //group is supplied, a
container-type window is created in which other windows may be created inside it.
Thus, if your .screenrc contains the lines
# example for .screenrc:
screen 1
screen -fn -t foobar -L 2 telnet foobar
screen creates a shell window (in window #1) and a window with a TELNET connection to the machine foobar
(with no flow-control using the title foobar in window #2) and will write a logfile (screenlog.2) of the
telnet session. Note, that unlike previous versions of screen no additional default window is created
when screen commands are included in your .screenrc file. When the initialization is completed, screen
switches to the last window specified in your .screenrc file or, if none, opens a default window #0.
Screen has built in some functionality of cu and telnet. See also chapter WINDOW TYPES.
scrollback num
Set the size of the scrollback buffer for the current windows to num lines. The default scrollback is 100
lines. See also the defscrollback command and use info to view the current setting. To access and use
the contents in the scrollback buffer, use the copy command.
select [WindowID]
Switch to the window identified by WindowID. This can be a prefix of a window title (alphanumeric window
name) or a window number. The parameter is optional and if omitted, you get prompted for an identifier.
When a new window is established, the first available number is assigned to this window. Thus, the first
window can be activated by select 0. The number of windows is set by the MAXWIN configuration parameter
(which defaults to 100), but it can be changed by using `maxwin' command. There are two special
WindowIDs, - selects the internal blank window and . selects the current window. The latter is useful if
used with screen's -X option.
sessionname [name]
Rename the current session. Note, that for screen -list the name shows up with the process-id prepended.
If the argument name is omitted, the name of this session is displayed. Caution: The $STY environment
variables will still reflect the old name in pre-existing shells. This may result in confusion. Use of
this command is generally discouraged. Use the -S command-line option if you want to name a new session.
The default is constructed from the tty and host names.
setenv [var [string]]
Set the environment variable var to value string. If only var is specified, the user will be prompted to
enter a value. If no parameters are specified, the user will be prompted for both variable and value.
The environment is inherited by all subsequently forked shells.
setsid [ on | off ]
Normally screen uses different sessions and process groups for the windows. If setsid is turned off, this
is not done anymore and all windows will be in the same process group as the screen backend process. This
also breaks job-control, so be careful. The default is on, of course. This command is probably useful
only in rare circumstances.
shell command
Set the command to be used to create a new shell. This overrides the value of the environment variable
$SHELL. This is useful if you'd like to run a tty-enhancer which is expecting to execute the program
specified in $SHELL. If the command begins with a '-' character, the shell will be started as a login-
shell. Typical shells do only minimal initialization when not started as a login-shell. E.g. Bash will
not read your ~/.bash_profile unless it is a login-shell.
shelltitle title
Set the title for all shells created during startup or by the C-A C-c command. For details about what a
title is, see the discussion entitled TITLES (naming windows).
silence [ on | off | sec ]
Toggles silence monitoring of windows. When silence is turned on and an affected window is switched into
the background, you will receive the silence notification message in the status line after a specified
period of inactivity (silence). The default timeout can be changed with the `silencewait' command or by
specifying a number of seconds instead of `on' or `off'. Silence is initially off for all windows.
silencewait sec
Define the time that all windows monitored for silence should wait before displaying a message. Default
30 seconds.
sleep num
This command will pause the execution of a .screenrc file for num seconds. Keyboard activity will end
the sleep. It may be used to give users a chance to read the messages output by echo.
slowpaste msec
Define the speed at which text is inserted into the current window by the paste ("C-a ]") command. If
the slowpaste value is nonzero text is written character by character. screen will make a pause of msec
milliseconds after each single character write to allow the application to process its input. Only use
slowpaste if your underlying system exposes flow control problems while pasting large amounts of text.
sort
Sort the windows in alphabetical order of the window tiles.
source file
Read and execute commands from file file. Source commands may be nested to a maximum recursion level of
ten. If file is not an absolute path and screen is already processing a source command, the parent
directory of the running source command file is used to search for the new command file before screen's
current directory.
Note that termcap/terminfo/termcapinfo commands only work at startup and reattach time, so they must be
reached via the default screenrc files to have an effect.
sorendition [attr[color]]
This command is deprecated. See "rendition so" instead.
split[-v]
Split the current region into two new ones. All regions on the display are resized to make room for the
new region. The blank window is displayed in the new region. The default is to create a horizontal split,
putting the new regions on the top and bottom of each other. Using `-v' will create a vertical split,
causing the new regions to appear side by side of each other. Use the remove or the only command to
delete regions. Use focus to toggle between regions.
When a region is split opposite of how it was previously split (that is, vertical then horizontal or
horizontal then vertical), a new layer is created. The layer is used to group together the regions that
are split the same. Normally, as a user, you should not see nor have to worry about layers, but they will
affect how some commands (focus and resize) behave.
With this current implementation of screen, scrolling data will appear much slower in a vertically split
region than one that is not. This should be taken into consideration if you need to use system commands
such as cat or tail -f.
startup_message [ on | off ]
Select whether you want to see the copyright notice during startup. Default is `on', as you probably
noticed.
status [ top | up | down | bottom ] [ left | right ]
The status window by default is in bottom-left corner. This command can move status messages to any
corner of the screen. top is the same as up, down is the same as bottom.
stuff [string]
Stuff the string string in the input buffer of the current window. This is like the paste command but
with much less overhead. Without a parameter, screen will prompt for a string to stuff. You cannot
paste large buffers with the stuff command. It is most useful for key bindings. See also bindkey.
su [username [password [password2]]]
Substitute the user of a display. The command prompts for all parameters that are omitted. If passwords
are specified as parameters, they have to be specified un-crypted. The first password is matched against
the systems passwd database, the second password is matched against the screen password as set with the
commands acladd or password. Su may be useful for the screen administrator to test multiuser setups.
When the identification fails, the user has access to the commands available for user nobody. These are
detach, license, version, help and displays.
suspend
Suspend screen. The windows are in the `detached' state, while screen is suspended. This feature relies
on the shell being able to do job control.
term term
In each window's environment screen opens, the $TERM variable is set to screen by default. But when no
description for screen is installed in the local termcap or terminfo data base, you set $TERM to - say -
vt100. This won't do much harm, as screen is VT100/ANSI compatible. The use of the term command is
discouraged for non-default purpose. That is, one may want to specify special $TERM settings (e.g.
vt100) for the next screen rlogin othermachine command. Use the command screen -T vt100 rlogin
othermachine rather than setting and resetting the default.
termcap term terminal-tweaks[window-tweaks]
terminfo term terminal-tweaks[window-tweaks]
termcapinfo term terminal-tweaks[window-tweaks]
Use this command to modify your terminal's termcap entry without going through all the hassles involved
in creating a custom termcap entry. Plus, you can optionally customize the termcap generated for the
windows. You have to place these commands in one of the screenrc startup files, as they are meaningless
once the terminal emulator is booted.
If your system uses the terminfo database rather than termcap, screen will understand the `terminfo'
command, which has the same effects as the `termcap' command. Two separate commands are provided, as
there are subtle syntactic differences, e.g. when parameter interpolation (using `%') is required. Note
that termcap names of the capabilities have to be used with the `terminfo' command.
In many cases, where the arguments are valid in both terminfo and termcap syntax, you can use the command
`termcapinfo', which is just a shorthand for a pair of `termcap' and `terminfo' commands with identical
arguments.
The first argument specifies which terminal(s) should be affected by this definition. You can specify
multiple terminal names by separating them with `|'s. Use `*' to match all terminals and `vt*' to match
all terminals that begin with vt.
Each tweak argument contains one or more termcap defines (separated by `:'s) to be inserted at the start
of the appropriate termcap entry, enhancing it or overriding existing values. The first tweak modifies
your terminal's termcap, and contains definitions that your terminal uses to perform certain 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:
termcap xterm* LP:hs@
Informs screen that all terminals that begin with `xterm' have firm auto-margins that allow the last
position on the screen to be updated (LP), but they don't really have a status line (no 'hs' - append `@'
to turn entries off). Note that we assume `LP' for all terminal names that start with vt, but only if
you don't specify a termcap command for that terminal.
termcap vt* LP
termcap vt102|vt220 Z0=\E[?3h:Z1=\E[?3l
Specifies the firm-margined `LP' capability for all terminals that begin with `vt', and the second line
will also add the escape-sequences to switch into (Z0) and back out of (Z1) 132-character-per-line mode
if this is a VT102 or VT220. (You must specify Z0 and Z1 in your termcap to use the width-changing
commands.)
termcap vt100 "" l0=PF1:l1=PF2:l2=PF3:l3=PF4
This leaves your vt100 termcap alone and adds the function key labels to each window's termcap entry.
termcap h19|z19 am@:im=\E@:ei=\EO dc=\E[P
Takes a h19 or z19 termcap and turns off auto-margins (am@) and enables the insert mode (im) and end-
insert (ei) capabilities (the `@' in the `im' string is after the `=', so it is part of the string).
Having the `im' and `ei' definitions put into your terminal's termcap will cause screen to automatically
advertise the character-insert capability in each window's termcap. Each window will also get the
delete-character capability (dc) added to its termcap, which screen will translate into a line-update for
the terminal (we're pretending it doesn't support character deletion).
If you would like to fully specify each window's termcap entry, you should instead set the $SCREENCAP
variable prior to running screen. See the discussion on the VIRTUAL TERMINAL in this manual, and the
termcap(5) man page for more information on termcap definitions.
time [string]
Uses the message line to display the time of day, the host name, and the load averages over 1, 5, and 15
minutes (if this is available on your system). For window specific information, use info.
If a string is specified, it changes the format of the time report like it is described in the STRING
ESCAPES chapter. Screen uses a default of "%c:%s %M %d %H%? %l%?".
title [windowtitle]
Set the name of the current window to windowtitle. If no name is specified, screen prompts for one. This
command was known as `aka' in previous releases.
unbindall
Unbind all the bindings. This can be useful when screen is used solely for its detaching abilities, such
as when letting a console application run as a daemon. If, for some reason, it is necessary to bind
commands after this, use 'screen -X'.
unsetenv var
Unset an environment variable.
utf8 [ on | off [ on | off ]]
Change the encoding used in the current window. If utf8 is enabled, the strings sent to the window will
be UTF-8 encoded and vice versa. Omitting the parameter toggles the setting. If a second parameter is
given, the display's encoding is also changed (this should rather be done with screen's -U option). See
also defutf8, which changes the default setting of a new window.
vbell [ on | off ]
Sets the visual bell setting for this window. Omitting the parameter toggles the setting. If vbell is
switched on, but your terminal does not support a visual bell, a `vbell-message' is displayed in the
status line when the bell character (^G) is received. Visual bell support of a terminal is defined by
the termcap variable `vb' (terminfo: 'flash').
Per default, vbell is off, thus the audible bell is used. See also `bell_msg'.
vbell_msg [message]
Sets the visual bell message. message is printed to the status line if the window receives a bell
character (^G), vbell is set to on, but the terminal does not support a visual bell. The default message
is Wuff, Wuff!!. Without a parameter, the current message is shown.
vbellwait sec
Define a delay in seconds after each display of screen's visual bell message. The default is 1 second.
verbose [ on | off ]
If verbose is switched on, the command name is echoed, whenever a window is created (or resurrected from
zombie state). Default is off. Without a parameter, the current setting is shown.
version
Print the current version and the compile date in the status line.
wall message
Write a message to all displays. The message will appear in the terminal's status line.
width [-w|-d] [cols [lines]]
Toggle the window width between 80 and 132 columns or set it to cols columns if an argument is specified.
This requires a capable terminal and the termcap entries Z0 and Z1. See the termcap command for more
information. You can also specify a new height if you want to change both values. The -w option tells
screen to leave the display size unchanged and just set the window size, -d vice versa.
windowlist [ -b ] [ -m ] [ -g ]
windowlist string [string]
windowlist title [title]
Display all windows in a table for visual window selection. If screen was in a window group, screen will
back out of the group and then display the windows in that group. If the -b option is given, screen will
switch to the blank window before presenting the list, so that the current window is also selectable.
The -m option changes the order of the windows, instead of sorting by window numbers screen uses its
internal most-recently-used list. The -g option will show the windows inside any groups in that level
and downwards.
The following keys are used to navigate in windowlist:
─────────────────────────────────────────────────────────────────────
k, C-p, or up Move up one line.
─────────────────────────────────────────────────────────────────────
j, C-n, or down Move down one line.
─────────────────────────────────────────────────────────────────────
C-g or escape Exit windowlist.
─────────────────────────────────────────────────────────────────────
C-a or home Move to the first line.
─────────────────────────────────────────────────────────────────────
C-e or end Move to the last line.
─────────────────────────────────────────────────────────────────────
C-u or C-d Move one half page up or down.
─────────────────────────────────────────────────────────────────────
C-b or C-f Move one full page up or down.
─────────────────────────────────────────────────────────────────────
0..9 Using the number keys, move to the selected line.
─────────────────────────────────────────────────────────────────────
mouseclick Move to the selected line. Available when
mousetrack is set to on
─────────────────────────────────────────────────────────────────────
/ Search.
─────────────────────────────────────────────────────────────────────
n Repeat search in the forward direction.
─────────────────────────────────────────────────────────────────────
N Repeat search in the backward direction.
─────────────────────────────────────────────────────────────────────
m Toggle MRU.
─────────────────────────────────────────────────────────────────────
g Toggle group nesting.
─────────────────────────────────────────────────────────────────────
a All window view.
─────────────────────────────────────────────────────────────────────
C-h or backspace Back out the group.
─────────────────────────────────────────────────────────────────────
, Switch numbers with the previous window.
─────────────────────────────────────────────────────────────────────
. Switch numbers with the next window.
─────────────────────────────────────────────────────────────────────
K Kill that window.
─────────────────────────────────────────────────────────────────────
space or enter Select that window.
─────────────────────────────────────────────────────────────────────
The table format can be changed with the string and title option, the title is displayed as table
heading, while the lines are made by using the string setting. The default setting is Num Name%=Flags for
the title and %3n %t%=%f for the lines. See the STRING ESCAPES chapter for more codes (e.g. color
settings).
Windowlist needs a region size of at least 10 characters wide and 6 characters high in order to display.
windows [ string ]
Uses the message line to display a list of all the windows. Each window is listed by number with the
name of process that has been started in the window (or its title); the current window is marked with a
`*'; the previous window is marked with a `-'; all the windows that are logged in are marked with a `$';
a background window that has received a bell is marked with a `!'; a background window that is being
monitored and has had activity occur is marked with an `@'; a window which has output logging turned on
is marked with `(L)'; windows occupied by other users are marked with `&'; windows in the zombie state
are marked with `Z'. If this list is too long to fit on the terminal's status line only the portion
around the current window is displayed. The optional string parameter follows the STRING ESCAPES format.
If string parameter is passed, the output size is unlimited. The default command without any parameter
is limited to a size of 1024 bytes.
wrap [ on | off ]
Sets the line-wrap setting for the current window. When line-wrap is on, the second consecutive
printable character output at the last column of a line will wrap to the start of the following line. As
an added feature, backspace (^H) will also wrap through the left margin to the previous line. Default is
`on'. Without any options, the state of wrap is toggled.
writebuf [-e encoding] [filename]
Writes the contents of the paste buffer to the specified file, or the public accessible screen-exchange
file if no filename is given. This is thought of as a primitive means of communication between screen
users on the same host. If an encoding is specified the paste buffer is recoded on the fly to match the
encoding. The filename can be set with the bufferfile command and defaults to /tmp/screen-exchange.
writelock [ on | off | auto]
In addition to access control lists, not all users may be able to write to the same window at once. Per
default, writelock is in `auto' mode and grants exclusive input permission to the user who is the first
to switch to the particular window. When he leaves the window, other users may obtain the writelock
(automatically). The writelock of the current window is disabled by the command writelock off. If the
user issues the command writelock on he keeps the exclusive write permission while switching to other
windows.
xoff
xon
Insert a CTRL-s / CTRL-q character to the stdin queue of the current window.
zmodem [ off | auto | catch | pass ]
zmodem sendcmd [string]
zmodem recvcmd [string]
Define zmodem support for screen. Screen understands two different modes when it detects a zmodem
request: pass and catch. If the mode is set to pass, screen will relay all data to the attacher until
the end of the transmission is reached. In catch mode screen acts as a zmodem endpoint and starts the
corresponding rz/sz commands. If the mode is set to auto, screen will use catch if the window is a tty
(e.g. a serial line), otherwise it will use pass.
You can define the templates screen uses in catch mode via the second and the third form.
Note also that this is an experimental feature.
zombie [keys[onerror]]
Per default screen windows are removed from the window list as soon as the windows process (e.g. shell)
exits. When a string of two keys is specified to the zombie command, `dead' windows will remain in the
list. The kill command may be used to remove such a window. Pressing the first key in the dead window
has the same effect. When pressing the second key, screen will attempt to resurrect the window. The
process that was initially running in the window will be launched again. Calling zombie without
parameters will clear the zombie setting, thus making windows disappear when their process exits.
As the zombie-setting is manipulated globally for all windows, this command should probably be called
defzombie, but it isn't.
Optionally you can put the word onerror after the keys. This will cause screen to monitor exit status of
the process running in the window. If it exits normally ('0'), the window disappears. Any other exit
value causes the window to become a zombie.
zombie_timeout[seconds]
Per default screen windows are removed from the window list as soon as the windows process (e.g. shell)
exits. If zombie keys are defined (compare with above zombie command), it is possible to also set a
timeout when screen tries to automatically reconnect a dead screen window.
THE MESSAGE LINE
Screen displays informational messages and other diagnostics in a message line. While this line is
distributed to appear at the bottom of the screen, it can be defined to appear at the top of the screen
during compilation. If your terminal has a status line defined in its termcap, screen will use this for
displaying its messages, otherwise a line of the current screen will be temporarily overwritten and
output will be momentarily interrupted. The message line is automatically removed after a few seconds
delay, but it can also be removed early (on terminals without a status line) by beginning to type.
The message line facility can be used by an application running in the current window by means of the
ANSI Privacy message control sequence. For instance, from within the shell, try something like:
echo '<esc>^Hello world from window '$WINDOW'<esc>\\'
where '<esc>' is an escape, '^' is a literal up-arrow, and '\\' turns into a single backslash.
WINDOW TYPES
Screen provides three different window types. New windows are created with screen's screen command (see
also the entry in chapter CUSTOMIZATION). The first parameter to the screen command defines which type of
window is created. The different window types are all special cases of the normal type. They have been
added in order to allow screen to be used efficiently as a console multiplexer with 100 or more windows.
• The normal window contains a shell (default, if no parameter is given) or any other system command
that could be executed from a shell (e.g. slogin, etc...)
• If a tty (character special device) name (e.g. /dev/ttya) is specified as the first parameter, then
the window is directly connected to this device. This window type is similar to screen cu -l
/dev/ttya. Read and write access is required on the device node, an exclusive open is attempted on
the node to mark the connection line as busy. An optional parameter is allowed consisting of a comma
separated list of flags in the notation used by stty(1):
<baud_rate>
Usually 300, 1200, 9600 or 19200. This affects transmission as well as receive speed.
cs8 or cs7
Specify the transmission of eight (or seven) bits per byte.
cstopb or -cstopb
Specify two stop bits per character (one with '-')
parenb or -parenb
Generate parity bit in output and expect parity bit in input
parodd or -parodd
Set odd parity (or even parity with '-')
ixon or -ixon
Enables (or disables) software flow-control (CTRL-S/CTRL-Q) for sending data.
ixoff or -ixoff
Enables (or disables) software flow-control for receiving data.
istrip or -istrip
Clear (or keep) the eight bit in each received byte.
You may want to specify as many of these options as applicable. Unspecified options cause the terminal
driver to make up the parameter values of the connection. These values are system dependent and may
be in defaults or values saved from a previous connection.
For tty windows, the info command shows some of the modem control lines in the status line. These may
include `RTS', `CTS', 'DTR', `DSR', `CD' and more. This depends on the available ioctl()'s and system
header files as well as the on the physical capabilities of the serial board. Signals that are
logical low (inactive) have their name preceded by an exclamation mark (!), otherwise the signal is
logical high (active). Signals not supported by the hardware but available to the ioctl() interface
are usually shown low.
When the CLOCAL status bit is true, the whole set of modem signals is placed inside curly braces ({
and }). When the CRTSCTS or TIOCSOFTCAR bit is set, the signals `CTS' or `CD' are shown in
parenthesis, respectively.
For tty windows, the command break causes the Data transmission line (TxD) to go low for a specified
period of time. This is expected to be interpreted as break signal on the other side. No data is sent
and no modem control line is changed when a break is issued.
• If the first parameter is //telnet, the second parameter is expected to be a host name, and an
optional third parameter may specify a TCP port number (default decimal 23). Screen will connect to a
server listening on the remote host and use the telnet protocol to communicate with that server.
For telnet windows, the command info shows details about the connection in square brackets ([ and ]) at
the end of the status line.
b BINARY. The connection is in binary mode.
e ECHO. Local echo is disabled.
c SGA. The connection is in `character mode' (default: `line mode').
t TTYPE. The terminal type has been requested by the remote host. Screen sends the name
screen unless instructed otherwise (see also the command `term').
w NAWS. The remote site is notified about window size changes.
f LFLOW. The remote host will send flow control information. (Ignored at the moment.)
Additional flags for debugging are x, t and n (XDISPLOC, TSPEED and NEWENV).
For telnet windows, the command break sends the telnet code IAC BREAK (decimal 243) to the remote
host.
This window type is only available if screen was compiled with the ENABLE_TELNET option defined.
STRING ESCAPES
Screen provides an escape mechanism to insert information like the current time into messages or file
names. The escape character is '%' with one exception: inside of a window's hardstatus '^%' ('^E') is
used instead.
Here is the full list of supported escapes:
% the escape character itself
E sets %? to true if the escape character has been pressed.
e encoding
f flags of the window, see windows for meanings of the various flags
F sets %? to true if the window has the focus
h hardstatus of the window
H hostname of the system
n window number
P sets %? to true if the current region is in copy/paste mode
S session name
s window size
t window title
u all other users on this window
w all window numbers and names. With '-' qualifier: up to the current window; with '+' qualifier:
starting with the window after the current one.
W all window numbers and names except the current one
x the executed command including arguments running in this windows
X the executed command without arguments running in this windows
? the part to the next '%?' is displayed only if a '%' escape inside the part expands to a non-empty
string
: else part of '%?'
= pad the string to the display's width (like TeX's hfill). If a number is specified, pad to the
percentage of the window's width. A '0' qualifier tells screen to treat the number as absolute
position. You can specify to pad relative to the last absolute pad position by adding a '+'
qualifier or to pad relative to the right margin by using '-'. The padding truncates the string if
the specified position lies before the current position. Add the 'L' qualifier to change this.
< same as '%=' but just do truncation, do not fill with spaces
> mark the current text position for the next truncation. When screen needs to do truncation, it
tries to do it in a way that the marked position gets moved to the specified percentage of the
output area. (The area starts from the last absolute pad position and ends with the position
specified by the truncation operator.) The 'L' qualifier tells screen to mark the truncated parts
with '...'.
{ attribute/color modifier string terminated by the next }
` Substitute with the output of a 'backtick' command. The length qualifier is misused to identify
one of the commands.
The 'c' and 'C' escape may be qualified with a '0' to make screen use zero instead of space as fill
character. The '0' qualifier also makes the '=' escape use absolute positions. The 'n' and '=' escapes
understand a length qualifier (e.g. '%3n'), 'D' and 'M' can be prefixed with 'L' to generate long names,
'w' and 'W' also show the window flags if 'L' is given.
An attribute/color modifier is used to change the attributes or the color settings. Its format is
[attribute modifier] [color description]. The attribute modifier must be prefixed by a change type
indicator if it can be confused with a color description. The following change types are known:
+ add the specified set to the current attributes
- remove the set from the current attributes
! invert the set in the current attributes
= change the current attributes to the specified set
The attribute set can either be specified as a hexadecimal number or a combination of the following
letters:
d dim
u underline
b bold
r reverse
s /standout
B blinking
Colors are coded either as a hexadecimal number or two letters specifying the desired background and
foreground color (in that order). The following colors are known:
k black
r red
g green
y yellow
b blue
m magenta
c cyan
w white
d default color
. leave color unchanged
The capitalized versions of the letter specify bright colors. You can also use the pseudo-color 'i' to
set just the brightness and leave the color unchanged.
A one digit/letter color description is treated as foreground or background color dependent on the
current attributes: if reverse mode is set, the background color is changed instead of the foreground
color. If you don't like this, prefix the color with a .. If you want the same behavior for two-letter
color descriptions, also prefix them with a ..
As a special case, %{-} restores the attributes and colors that were set before the last change was made
(i.e., pops one level of the color-change stack).
Examples:
G set color to bright green
+b r use bold red
= yd clear all attributes, write in default color on yellow background.
%-Lw%{= BW}%50>%n%f* %t%{-}%+Lw%<
The available windows centered at the current window and truncated to the available width. The
current window is displayed white on blue. This can be used with hardstatus alwayslastline.
%?%F%{.R.}%?%3n %t%? [%h]%?
The window number and title and the window's hardstatus, if one is set. Also use a red background
if this is the active focus. Useful for caption string.
FLOW-CONTROL
Each window has a flow-control setting that determines how screen deals with the XON and XOFF characters
(and perhaps the interrupt character). When flow-control is turned off, screen ignores the XON and XOFF
characters, which allows the user to send them to the current program by simply typing them (useful for
the emacs editor, for instance). The trade-off is that it will take longer for output from a normal
program to pause in response to an XOFF. With flow-control turned on, XON and XOFF characters are used
to immediately pause the output of the current window. You can still send these characters to the
current program, but you must use the appropriate two-character screen commands (typically C-a q (xon)
and C-a s (xoff)). The xon/xoff commands are also useful for typing C-s and C-q past a terminal that
intercepts these characters.
Each window has an initial flow-control value set with either the -f option or the defflow .screenrc
command. Per default the windows are set to 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 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.
TITLES (naming windows)
You can customize each window's name in the window display (viewed with the windows command (C-a w)) by
setting it with one of the title commands. 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 in the .screenrc file,
while all other windows are created with a screen command and thus can have their name set with the -t
option. Interactively, there is the title-string escape-sequence (<esc>kname<esc>\) and the title
command (C-a A). The former can be output from an application to control the window's name under
software control, and the latter will prompt for a name when typed. You can also bind pre-defined names
to keys with the title command to set things quickly without prompting. Changing title by this escape
sequence can be controlled by defdynamictitle and dynamictitle commands.
Finally, screen has a shell-specific heuristic that is enabled by setting the window's name to
search|name and arranging to have a null title escape-sequence output as a part of your prompt. The
search portion specifies an end-of-prompt search string, while the name portion specifies the default
shell name for the window. If the name ends in a `:' screen will add what it believes to be the current
command running in the window to the end of the 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 title-escape-sequence
(<esc>k<esc>\) as a part of your prompt. The last part of your prompt must be the same as the string you
specified for the search portion of the title. Once this is set up, screen will use the title-escape-
sequence to clear the previous command name and get ready for the next command. Then, when a newline is
received from the shell, a search is made for the end of the prompt. If found, it will grab the first
word after the matched string and use it as the command name. If the command name begins with either
'!', '%', or '^' screen will use the first word on the following line (if found) in preference to the
just-found name. This helps csh users get better command names when using job control or history recall
commands.
Here's some .screenrc examples:
screen -t top 2 nice top
Adding this line to your .screenrc would start a nice-d version of the top command in window 2 named top
rather than nice.
shelltitle '> |csh'
screen 1
These commands would start a shell with the given shelltitle. The title specified is an auto-title that
would expect the prompt and the typed command to look something like the following:
/usr/joe/src/dir> trn
(it looks after the '> ' for the command name). The window status would show the name trn while the
command was running, and revert to csh upon 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-title's current setting (C-a E). The third binding would set the
current window's title to (unknown) (C-a u).
One thing to keep in mind when adding a null title-escape-sequence to your prompt is that some shells
(like the csh) count all the non-control characters as part of the prompt's length. If these invisible
characters aren't a multiple of 8 then backspacing over a tab will result in an incorrect display. One
way to get around this is to use a prompt like this:
set prompt='^[[0000m^[k^[\% '
The escape-sequence <esc>[0000m not only normalizes the character attributes, but all the zeros round the
length of the invisible characters up to 8. Bash users will probably want to echo the escape sequence in
the PROMPT_COMMAND:
PROMPT_COMMAND='printf "\033k\033\134"'
(I used \134 to output a `\' because of a bug in bash v1.04).
THE VIRTUAL TERMINAL
Each window in a screen session emulates a VT100 terminal, with some extra functions added. The VT100
emulator is hard-coded, no other terminal types can be emulated.
Usually screen tries to emulate as much of the VT100/ANSI standard as possible. But if your terminal
lacks certain capabilities, the emulation may not be complete. In these cases screen has to tell the
applications that some of the features are missing. This is no problem on machines using termcap, because
screen can use the $TERMCAP variable to customize the standard screen termcap.
But if you do a rlogin on another machine or your machine supports only terminfo this method fails.
Because of this, screen offers a way to deal with these cases. Here is how it works:
When screen tries to figure out a terminal name for itself, it first looks for an entry named
screen.<term>, where <term> is the contents of your $TERM variable. If no such entry exists, screen
tries screen (or screen-w if the terminal is wide (132 cols or more)). If even this entry cannot be
found, vt100 is used as a substitute.
The idea is that if you have a terminal which doesn't support an important feature (e.g. delete char or
clear to EOS) you can build a new termcap/terminfo entry for screen (named screen.<dumbterm>) in which
this capability has been disabled. If this entry is installed on your machines you are able to do a
rlogin and still keep the correct termcap/terminfo entry. The terminal name is put in the $TERM variable
of all new windows. Screen also sets the $TERMCAP variable reflecting the capabilities of the virtual
terminal emulated. Notice that, however, on machines using the terminfo database this variable has no
effect. Furthermore, the variable $WINDOW is set to the window number of each window.
The actual set of capabilities supported by the virtual terminal depends on the capabilities supported by
the physical terminal. If, for instance, the physical terminal does not support underscore mode, screen
does not put the `us' and `ue' capabilities into the window's $TERMCAP variable, accordingly. However, a
minimum number of capabilities must be supported by a terminal in order to run screen; namely scrolling,
clear screen, and direct cursor addressing (in addition, screen does not run on hardcopy terminals or on
terminals that over-strike).
Also, you can customize the $TERMCAP value used by screen by using the termcap .screenrc command, or by
defining the variable $SCREENCAP prior to startup. When the latter is 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. The info command displays a line starting `PRIN' while
the printer is active.
Screen maintains a hardstatus line for every window. If a window gets selected, the display's hardstatus
will be updated to match the window's hardstatus line. If the display has no hardstatus the line will be
displayed as a standard screen message. The hardstatus line can be changed with the ANSI Application
Program Command (APC): ESC_<string>ESC\. As a convenience for xterm users the sequence
ESC]0..2;<string>^G is also accepted.
Some capabilities are only put into the $TERMCAP variable of the virtual terminal if they can be
efficiently implemented by the physical terminal. For instance, `dl' (delete line) is only put into the
$TERMCAP variable if the terminal supports either delete line itself or scrolling regions. Note that this
may provoke confusion, when the session is reattached on a different terminal, as the value of $TERMCAP
cannot be modified by parent processes.
The "alternate screen" capability is not enabled by default. Set the altscreen .screenrc command to
enable it.
The following is a list of control sequences recognized by screen. (V) and (A) indicate VT100-specific
and ANSI- or ISO-specific functions, 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
Pn = 7 Visible
ESC = (V) Application Keypad Mode
ESC > (V) Numeric Keypad Mode
ESC # 8 (V) Fill Screen with E's
ESC \ (A) String Terminator
ESC ^ (A) Privacy Message String (Message Line)
ESC ! Global Message String (Message Line)
ESC k A.k.a. Definition String
ESC P (A) Device Control String. Outputs a string directly to the host terminal without
interpretation.
ESC _ (A) Application Program Command (Hardstatus)
ESC ] 0 ; string ^G (A) Operating System Command (Hardstatus, xterm title hack)
ESC ] 83 ; cmd ^G (A) Execute screen command. This only works if multi-user support is compiled into
screen. The pseudo-user :window: is used to check the access control list. Use
addacl :window: -rwx #? to create a user with no rights and allow only the
needed commands.
Control-N (A) Lock Shift G1 (SO)
Control-O (A) Lock Shift G0 (SI)
ESC n (A) Lock Shift G2
ESC o (A) Lock Shift G3
ESC N (A) Single Shift G2
ESC O (A) Single Shift G3
ESC ( Pcs (A) Designate character set as G0
ESC ) Pcs (A) Designate character set as G1
ESC * Pcs (A) Designate character set as G2
ESC + Pcs (A) Designate character set as G3
ESC [ Pn ; Pn H Direct Cursor Addressing
ESC [ Pn ; Pn f same as above
ESC [ Pn J Erase in Display
Pn = None or 0 From Cursor to End of Screen
Pn = 1 From Beginning of Screen to Cursor
Pn = 2 Entire Screen
ESC [ Pn K Erase in Line
Pn = None or 0 From Cursor to End of Line
Pn = 1 From Beginning of Line to Cursor
Pn = 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
Ps = 1 Bold
Ps = 2 (A) Faint
Ps = 3 (A) Standout Mode (ANSI: Italicized)
Ps = 4 Underlined
Ps = 5 Blinking
Ps = 7 Negative Image
Ps = 22 (A) Normal Intensity
Ps = 23 (A) Standout Mode off (ANSI: Italicized off)
Ps = 24 (A) Not Underlined
Ps = 25 (A) Not Blinking
Ps = 27 (A) Positive Image
Ps = 30 (A) Foreground Black
Ps = 31 (A) Foreground Red
Ps = 32 (A) Foreground Green
Ps = 33 (A) Foreground Yellow
Ps = 34 (A) Foreground Blue
Ps = 35 (A) Foreground Magenta
Ps = 36 (A) Foreground Cyan
Ps = 37 (A) Foreground White
Ps = 39 (A) Foreground Default
Ps = 40 (A) Background Black
Ps = ...
Ps = 49 (A) Background Default
ESC [ Pn g Tab Clear
Pn = None or 0 Clear Tab at Current Position
Pn = 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
Ps = 20 (A) Automatic Linefeed Mode
Ps = 34 Normal Cursor Visibility
Ps = ?1 (V) Application Cursor Keys
Ps = ?3 (V) Change Terminal Width to 132 columns
Ps = ?5 (V) Reverse Video
Ps = ?6 (V) Origin Mode
Ps = ?7 (V) Wrap Mode
Ps = ?9 X10 mouse tracking
Ps = ?25 (V) Visible Cursor
Ps = ?47 Alternate Screen (old xterm code)
Ps = ?1000 (V) VT200 mouse tracking
Ps = ?1047 Alternate Screen (new xterm code)
Ps = ?1049 Alternate Screen (new xterm code)
ESC [ 5 i (A) Start relay to printer (ANSI Media Copy)
ESC [ 4 i (A) Stop relay to printer (ANSI Media Copy)
ESC [ 8 ; Ph ; Pw t Resize the window to `Ph' lines and `Pw' columns (SunView special)
ESC [ c Send VT100 Identification String
ESC [ x Send Terminal Parameter Report
ESC [ > c Send VT220 Secondary Device Attributes String
ESC [ 6 n Send Cursor Position Report
INPUT TRANSLATION
In order to do a full VT100 emulation screen has to detect that a sequence of characters in the input
stream was generated by a keypress on the user's keyboard and insert the VT100 style escape sequence.
Screen has a very flexible way of doing this by making it possible to map arbitrary commands on 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 in the command table). Because the sequences
generated by a keypress can change after a reattach from a different terminal type, it is possible to
bind commands to the termcap name of the keys. Screen will insert the correct binding after each
reattach. See the bindkey command for further details on the syntax and examples.
Here is the table of the default key bindings. The fourth is what command is executed if the keyboard is
switched into application mode.
┌─────────────────┬──────────────┬──────────┬──────────┐
│ Key name │ Termcap name │ Command │ App mode │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Cursor up │ ku │ \033[A │ \033OA │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Cursor down │ kd │ \033[B │ \033OB │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Cursor right │ kr │ \033[C │ \033OC │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Cursor left │ kl │ \033[D │ \033OD │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Function key 0 │ k0 │ \033[10~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Function key 1 │ k1 │ \033OP │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Function key 2 │ k2 │ \033OQ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Function key 3 │ k3 │ \033OR │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Function key 4 │ k4 │ \033OS │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Function key 5 │ k5 │ \033[15~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Function key 6 │ k6 │ \033[17~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Function key 7 │ k7 │ \033[18~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Function key 8 │ k8 │ \033[19~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Function key 9 │ k9 │ \033[20~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Function key 10 │ k; │ \033[21~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Function key 11 │ F1 │ \033[23~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Function key 12 │ F2 │ \033[24~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Home │ kh │ \033[1~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ End │ kH │ \033[4~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Insert │ kI │ \033[2~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Delete │ kD │ \033[3~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Page up │ kP │ \033[5~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Page down │ kN │ \033[6~ │ │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad 0 │ f0 │ 0 │ \033Op │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad 1 │ f1 │ 1 │ \033Oq │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad 2 │ f2 │ 2 │ \033Or │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad 3 │ f3 │ 3 │ \033Os │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad 4 │ f4 │ 4 │ \033Ot │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad 5 │ f5 │ 5 │ \033Ou │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad 6 │ f6 │ 6 │ \033Ov │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad 7 │ f7 │ 7 │ \033Ow │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad 8 │ f8 │ 8 │ \033Ox │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad 9 │ f9 │ 9 │ \033Oy │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad + │ f+ │ + │ \033Ok │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad - │ f- │ - │ \033Om │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad * │ f* │ * │ \033Oj │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad / │ f/ │ / │ \033Oo │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad = │ fq │ = │ \033OX │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad . │ f. │ . │ \033On │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad , │ f, │ , │ \033Ol │
├─────────────────┼──────────────┼──────────┼──────────┤
│ Keypad enter │ fe │ \015 │ \033OM │
└─────────────────┴──────────────┴──────────┴──────────┘
SPECIAL TERMINAL CAPABILITIES
The following table describes all terminal capabilities that are recognized by screen and are not in the
termcap(5) manual. You can place these capabilities in your termcap entries (in `/etc/termcap') or use
them with the commands `termcap', `terminfo' and `termcapinfo' in your screenrc files. It is often not
possible to place these capabilities in the terminfo database.
LP (bool) Terminal has VT100 style margins (`magic margins'). Note that this capability is obsolete
because screen uses the standard 'xn' instead.
Z0 (str) Change width to 132 columns.
Z1 (str) Change width to 80 columns.
WS (str) Resize display. This capability has the desired width and height as arguments. SunView(tm)
example: '\E[8;%d;%dt'.
NF (bool) Terminal doesn't need flow control. Send ^S and ^Q direct to the application. Same as 'flow
off'. The opposite of this capability is 'nx'.
G0 (bool) Terminal can deal with ISO 2022 font selection sequences.
S0 (str) Switch charset 'G0' to the specified charset. Default is '\E(%.'.
E0 (str) Switch charset 'G0' back to standard charset. Default is '\E(B'.
C0 (str) Use the string as a conversion table for font '0'. See the 'ac' capability for more details.
CS (str) Switch cursor-keys to application mode.
CE (str) Switch cursor-keys back to normal mode.
AN (bool) Turn on autonuke. See the 'autonuke' command for more details.
OL (num) Set the output buffer limit. See the 'obuflimit' command for more details.
KJ (str) Set the encoding of the terminal. See the 'encoding' command for valid encodings.
AF (str) Change character foreground color in an ANSI conform way. This capability will almost always
be set to '\E[3%dm' ('\E[3%p1%dm' on terminfo machines).
AB (str) Same as 'AF', but change background color.
AX (bool) Does understand ANSI set default fg/bg color (\E[39m / \E[49m).
XC (str) Describe a translation of characters to strings depending on the current font. More details
follow in the next section.
XT (bool) Terminal understands special xterm sequences (OSC, mouse tracking).
C8 (bool) Terminal needs bold to display high-intensity colors (e.g. Eterm).
TF (bool) Add missing capabilities to the termcap/info entry. (Set by default).
CHARACTER TRANSLATION
Screen has a powerful mechanism to translate characters to arbitrary strings depending on the current
font and terminal type. Use this feature if you want to work with a common standard character set (say
ISO8851-latin1) even on terminals that scatter the more unusual characters over several national language
font pages.
Syntax:
XC=<charset-mapping>{,,<charset-mapping>}
<charset-mapping> := <designator><template>{,<mapping>}
<mapping> := <char-to-be-mapped><template-arg>
The things in braces may be repeated any number of times.
A <charset-mapping> tells screen how to map characters in font <designator> ('B': Ascii, 'A': UK, 'K':
German, etc.) to strings. Every <mapping> describes to what string a single character will be
translated. A template mechanism is used, as most of the time the codes have a lot in common (for example
strings to switch to and from another charset). Each occurrence of '%' in <template> gets substituted
with the <template-arg> specified together with the character. If your strings are not similar at all,
then use '%' as a template and place the full string in <template-arg>. A quoting mechanism was added to
make it possible to use a real '%'. The '\' character quotes the special characters '\', '%', and ','.
Here is an example:
termcap hp700 'XC=B\E(K%\E(B,\304[,\326\\\\,\334]'
This tells screen how to translate ISOlatin1 (charset 'B') upper case umlaut characters on a hp700
terminal that has a German charset. '\304' gets 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'.
ENVIRONMENT
COLUMNS Number of columns on the terminal (overrides termcap entry).
HOME Directory in which to look for .screenrc.
LINES Number of lines on the terminal (overrides termcap entry).
LOCKPRG Screen lock program.
NETHACKOPTIONS Turns on nethack option.
PATH Used for locating programs to run.
SCREENCAP For customizing a terminal's TERMCAP value.
SCREENDIR Alternate socket directory.
SCREENRC Alternate user screenrc file.
SHELL Default shell program for opening windows (default /bin/sh). See also shell .screenrc
command.
STY Alternate socket name.
SYSSCREENRC Alternate system screenrc file.
TERM Terminal name.
TERMCAP Terminal description.
WINDOW Window number of a window (at creation time).
FILES
.../screen-4.?.??/etc/screenrc
.../screen-4.?.??/etc/etcscreenrc Examples in the screen distribution package for private and global
initialization files.
$SYSSCREENRC
/etc/screenrc screen initialization commands
$SCREENRC
$HOME/.screenrc Read in after /etc/screenrc
$SCREENDIR/S-<login>
/run/screen/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
/run/utmp Login records
$LOCKPRG Program that locks a terminal.
AUTHORS
Originally created by Oliver Laumann. For a long time maintained and developed by Juergen Weigert,
Michael Schroeder, Micah Cowan and Sadrul Habib Chowdhury. Since 2015 maintained and developed by
Amadeusz Slawinski <amade@asmblr.net> and Alexander Naumov <alexander_naumov@opensuse.org>.
COPYLEFT
Copyright (c) 2018-2023
Alexander Naumov <alexander_naumov@opensuse.org>
Amadeusz Slawinski <amade@asmblr.net>
Copyright (c) 2015-2017
Juergen Weigert <jnweiger@immd4.informatik.uni-erlangen.de>
Alexander Naumov <alexander_naumov@opensuse.org>
Amadeusz Slawinski <amade@asmblr.net>
Copyright (c) 2010-2015
Juergen Weigert <jnweiger@immd4.informatik.uni-erlangen.de>
Sadrul Habib Chowdhury <sadrul@users.sourceforge.net>
Copyright (c) 2008, 2009
Juergen Weigert <jnweiger@immd4.informatik.uni-erlangen.de>
Michael Schroeder <mlschroe@immd4.informatik.uni-erlangen.de>
Micah Cowan <micah@cowan.name>
Sadrul Habib Chowdhury <sadrul@users.sourceforge.net>
Copyright (C) 1993-2003
Juergen Weigert <jnweiger@immd4.informatik.uni-erlangen.de>
Michael Schroeder <mlschroe@immd4.informatik.uni-erlangen.de>
Copyright (C) 1987 Oliver Laumann
This program is free software; you can redistribute it and/or modify it under the terms of the GNU
General Public License as published by the Free Software Foundation; either version 3, or (at your
option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
License for more details.
You should have received a copy of the GNU General Public License along with this program (see the file
COPYING); if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA
CONTRIBUTORS
Vincent Lefevre <vincent@vinc17.net>,
Carl Drougge <bearded@longhaired.org>,
Maarten ter Huurne <maarten@treewalker.org>,
Jussi Kukkonen <jussi.kukkonen@intel.com>,
Eric S. Raymond <esr@thyrsus.com>,
Thomas Renninger <treen@suse.com>,
Axel Beckert <abe@deuxchevaux.org>,
Ken Beal <kbeal@amber.ssd.csd.harris.com>,
Rudolf Koenig <rfkoenig@immd4.informatik.uni-erlangen.de>,
Toerless Eckert <eckert@immd4.informatik.uni-erlangen.de>,
Wayne Davison <davison@borland.com>,
Patrick Wolfe <pat@kai.com, kailand!pat>,
Bart Schaefer <schaefer@cse.ogi.edu>,
Nathan Glasser <nathan@brokaw.lcs.mit.edu>,
Larry W. Virden <lvirden@cas.org>,
Howard Chu <hyc@hanauma.jpl.nasa.gov>,
Tim MacKenzie <tym@dibbler.cs.monash.edu.au>,
Markku Jarvinen <mta@{cc,cs,ee}.tut.fi>,
Marc Boucher <marc@CAM.ORG>,
Doug Siebert <dsiebert@isca.uiowa.edu>,
Ken Stillson <stillson@tsfsrv.mitre.org>,
Ian Frechett <frechett@spot.Colorado.EDU>,
Brian Koehmstedt <bpk@gnu.ai.mit.edu>,
Don Smith <djs6015@ultb.isc.rit.edu>,
Frank van der Linden <vdlinden@fwi.uva.nl>,
Martin Schweikert <schweik@cpp.ob.open.de>,
David Vrona <dave@sashimi.lcu.com>,
E. Tye McQueen <tye%spillman.UUCP@uunet.uu.net>,
Matthew Green <mrg@eterna.com.au>,
Christopher Williams <cgw@pobox.com>,
Matt Mosley <mattm@access.digex.net>,
Gregory Neil Shapiro <gshapiro@wpi.WPI.EDU>,
Johannes Zellner <johannes@zellner.org>,
Pablo Averbuj <pablo@averbuj.com>.
AVAILABILITY
The latest official release of screen available via anonymous ftp from ftp.gnu.org/gnu/screen/ or any
other GNU distribution site. The home page of screen is https://savannah.gnu.org/projects/screen/ and the
git repo is https://git.savannah.gnu.org/cgit/screen.git. If you want to help, send a note to screen-
devel@gnu.org.
BUGS
• `dm' (delete mode) and `xs' are not handled correctly (they are ignored). `xn' is treated as a magic-
margin indicator.
• Screen has no clue about double-high or double-wide characters. But this is the only area where
vttest is allowed to fail.
• It is not possible to change the environment variable $TERMCAP when reattaching under a different
terminal type.
• The support of terminfo based systems is very limited. Adding extra capabilities to $TERMCAP may not
have any effects.
• Screen does not make use of hardware tabs.
• Screen must be installed as set-uid with owner root on most systems in order to be able to correctly
change the owner of the tty device file for each window. Special permission may also be required to
write the file /run/utmp.
• Entries in /run/utmp are not removed when screen is killed with SIGKILL. This will cause some
programs (like "w" or "rwho") to advertise that a user is logged on who really isn't.
• Screen may give a strange warning when your tty has no utmp entry.
• When the modem line was hung up, screen may not automatically detach (or quit) unless the device
driver is configured to send a HANGUP signal. To detach a screen session use the -D or -d command
line option.
• If a password is set, the command line options -d and -D still detach a session without asking.
• Both breaktype and defbreaktype change the break generating method used by all terminal devices. The
first should change a window specific setting, where the latter should change only the default for new
windows.
• When attaching to a multiuser session, the user's .screenrc file is not sourced. Each user's personal
settings have to be included in the .screenrc file from which the session is booted, or have to be
changed manually.
• A weird imagination is most useful to gain full advantage of all the features.
Send bug-reports, fixes, enhancements, t-shirts, money, beer & pizza to screen-devel@gnu.org.
SEE ALSO
termcap(5), utmp(5), vi(1), captoinfo(1), tic(1), tty(4), pty(7)
GNU Screen 4.9.1 2023 Aug 20 SCREEN(1)