Screen provides three different window types. New windows are
created with screen's screen command (see also the entry in
chapter "CUSTOMIZATION"). The first parameter to the screen
command defines which type of window is created. The different
window types are all special cases of the normal type. They have
been added in order to allow screen to be used efficiently as a
console multiplexer with 100 or more windows.
• The normal window contains a shell (default, if no parameter
is given) or any other system command that could be executed
from a shell (e.g. slogin, etc...)
• If a tty (character special device) name (e.g. "/dev/ttya") is
specified as the first parameter, then the window is directly
connected to this device. This window type is similar to
"screen cu -l /dev/ttya". Read and write access is required
on the device node, an exclusive open is attempted on the node
to mark the connection line as busy. An optional parameter is
allowed consisting of a comma separated list of flags in the
notation used by stty(1):
<baud_rate>
Usually 300, 1200, 9600 or 19200. This affects
transmission as well as receive speed.
cs8 or cs7
Specify the transmission of eight (or seven) bits per
byte.
ixon or -ixon
Enables (or disables) software flow-control (CTRL-
S/CTRL-Q) for sending data.
ixoff or -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.
