Where to run getty(8) processes is normally defined by ttys(5).
There is a default terminal class, default, that is used to set global defaults for all other classes. (That is, the default entry is read, then the entry for the class required is used to override particular settings.) The default entry is also normally read by other programs that present login prompts to the user, such as telnetd(8), in order to retrieve the values of the he, hn, im, and if capabilities.
Name Type Default Description | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
ab bool false Auto-baud speed select mechanism for the Micom 600 portselector. Selection is done by looking at how the character `\r' is garbled at 300, 1200, 4800, and 9600 baud. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
al str NULL user to auto-login instead of prompting | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
ap bool false terminal uses any parity | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
bk str 0377 alternative end of line character (input break) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
b2 str 0377 alternative end of line character (input break) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
c0 num unused tty control flags to write messages | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
c1 num unused tty control flags to read login name | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
c2 num unused tty control flags to leave terminal as | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
ce bool false use crt erase algorithm | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
ck bool false use crt kill algorithm | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
cl str |
NULL |
The following capabilities are no longer supported by getty(8):
bd num 0 backspace delay |
cb bool false use crt backspace mode |
cd num 0 carriage-return delay |
fd num 0 form-feed (vertical motion) delay |
nd num 0 newline (line-feed) delay |
uc bool false terminal is known upper case only |
If no line speed is specified, speed will not be altered from that which prevails when getty is entered. Specifying an input or output speed will override line speed for stated direction only.
Terminal modes to be used for the output of the message, for input of the login name, and to leave the terminal set as upon completion, are derived from the boolean flags specified. If the derivation should prove inadequate, any (or all) of these three may be overridden with one of the c0, c1, c2, i0, i1, i2, l0, l1, l2, o0, o1, or o2 numeric specifications, which can be used to specify (usually in octal, with a leading '0') the exact values of the flags. These flags correspond to the termios c_cflag, c_iflag, c_lflag, and c_oflag fields, respectively. Each these sets must be completely specified to be effective. The f0, f1, and f2 are excepted for backwards compatibility with a previous incarnation of the TTY sub-system. In these flags the bottom 16 bits of the (32 bits) value contain the sgttyb sg_flags field, while the top 16 bits represent the local mode word.
Should getty(8) receive a null character (presumed to indicate a line break) it will restart using the table indicated by the nx entry. If there is none, it will re-use its original table.
Delays are specified in milliseconds, the nearest possible delay available in the tty driver will be used. Should greater certainty be desired, delays with values 0, 1, 2, and 3 are interpreted as choosing that particular delay algorithm from the driver.
The cl screen clear string may be preceded by a (decimal) number of milliseconds of delay required (a la termcap). This delay is simulated by repeated use of the pad character pc.
The initial message, and login message, im and lm may include any of the following character sequences, which expand to information about the environment in which getty(8) is running.
When getty execs the login process, given
in the
lo
string (usually
``/usr/bin/login
''),
it will have set
the environment to include the terminal type, as indicated
by the
tt
string (if it exists).
The
ev
string, can be used to enter additional data into
the environment.
It is a list of comma separated strings, each of which
will presumably be of the form
name=value.
If a non-zero timeout is specified, with to, then getty will exit within the indicated number of seconds, either having received a login name and passed control to login(1), or having received an alarm signal, and exited. This may be useful to hangup dial in lines.
Output from
getty(8)
is even parity unless
op
or
np
is specified.
The
op
string
may be specified with
ap
to allow any parity on input, but generate odd parity output.
Note: this only applies while getty is being run,
terminal driver limitations prevent a more complete
implementation.
getty(8)
does not check parity of input characters in
RAW
mode.
If pp string is specified and a Point to Point Protocol (PPP) link bringup sequence is recognized, getty(8) will invoke the program referenced by the pp string, e.g. pppd(8). This can be used to handle incoming PPP calls.
The delay stuff is a real crock. Apart from its general lack of flexibility, some of the delay algorithms are not implemented. The terminal driver should support sane delay settings.
The he capability is stupid.
The termcap(5) format is horrid, something more rational should have been chosen.