screen: Window Types
6.6 Window Types
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Screen provides three different window types. New windows are created
with 'screen''s 'screen' command (⇒Screen Command). The first
parameter to the 'screen' command defines which type of window is
created. The different window types are all special cases of the normal
type. They have been added in order to allow 'screen' to be used
efficiently as a console with 100 or more windows.
* The normal window contains a shell (default, if no parameter is
given) or any other system command that could be executed from a
shell. (e.g. 'slogin', etc...).
* If a tty (character special device) name (e.g. '/dev/ttya') is
specified as the first parameter, then the window is directly
connected to this device. This window type is similar to 'screen
cu -l /dev/ttya'. Read and write access is required on the device
node, an exclusive open is attempted on the node to mark the
connection line as busy. An optional parameter is allowed
consisting of a comma separated list of flags in the notation used
by 'stty(1)':
'<baud_rate>'
Usually 300, 1200, 9600 or 19200. This affects transmission
as well as receive speed.
'cs8 or cs7'
Specify the transmission of eight (or seven) bits per byte.
'ixon or -ixon'
Enables (or disables) software flow-control (CTRL-S/CTRL-Q)
for sending data.
'ixoff or -ixoff'
Enables (or disables) software flow-control for receiving
data.
'istrip or -istrip'
Clear (or keep) the eight bit in each received byte.
You may want to specify as many of these options as applicable.
Unspecified options cause the terminal driver to make up the
parameter values of the connection. These values are
system-dependent and may be in defaults or values saved from a
previous connection.
For tty windows, the 'info' command shows some of the modem control
lines in the status line. These may include 'RTS', 'CTS', 'DTR',
'CD' and more. This depends rather on on the available 'ioctl()''s
and system header files than on the physical capabilities of the
serial board. The name of a logical low (inactive) signal is
preceded by an exclamation mark ('!'), otherwise the signal is
logical high (active). Unsupported but shown signals are usually
shown low. When the 'CLOCAL' status bit is true, the whole set of
modem signals is placed inside curly braces ('{' and '}'). When
the 'CRTSCTS' or 'TIOCSOFTCAR' bit is true, the signals 'CTS' or
'CD' are shown in parenthesis, respectively.
For tty windows, the command 'break' causes the Data transmission
line (TxD) to go low for a specified period of time. This is
expected to be interpreted as break signal on the other side. No
data is sent and no modem control line is changed when a 'break' is
issued.
* If the first parameter is '//telnet', the second parameter is
expected to be a host name, and an optional third parameter may
specify a TCP port number (default decimal 23). Screen will
connect to a server listening on the remote host and use the telnet
protocol to communicate with that server.
For telnet windows, the command 'info' shows details about the
connection in square brackets ('[' and ']') at the end of the
status line.
'b'
BINARY. The connection is in binary mode.
'e'
ECHO. Local echo is disabled.
'c'
SGA. The connection is in 'character mode' (default: 'line
mode').
't'
TTYPE. The terminal type has been requested by the remote
host. Screen sends the name 'screen' unless instructed
otherwise (see also the command 'term').
'w'
NAWS. The remote site is notified about window size changes.
'f'
LFLOW. The remote host will send flow control information.
(Ignored at the moment.)
Additional flags for debugging are 'x', 't' and 'n' (XDISPLOC,
TSPEED and NEWENV).
For telnet windows, the command 'break' sends the telnet code 'IAC
BREAK' (decimal 243) to the remote host.
Info Catalog
screen: Term
screen: New Window
screen: Window Groups