GETTY(1M) (Essential Utilities) GETTY(1M)
NAME
getty - set terminal type, modes, speed, and line discipline
SYNOPSIS
/etc/getty [ -h ] [ -t timeout ] line [ speed [ type [
linedisc ] ] ]
/etc/getty -c file
DESCRIPTION
getty is a program that is invoked by init(1M). It is the
second process in the series, (init-getty-login-shell) that
ultimately connects a user with the system. It can only be
executed by the super-user; that is, a process with the
user-ID of root. Initially getty prints the login message
field for the entry it is using from /etc/gettydefs. getty
reads the user's login name and invokes the login(1) command
with the user's name as argument. While reading the name,
getty attempts to adapt the system to the speed and type of
terminal being used. It does this by using the options and
arguments specified.
Line is the name of a tty line in /dev to which getty is to
attach itself. getty uses this string as the name of a file
in the /dev directory to open for reading and writing.
Unless getty is invoked with the -h flag, getty will force a
hangup on the line by setting the speed to zero before
setting the speed to the default or specified speed. The -t
flag plus timeout (in seconds), specifies that getty should
exit if the open on the line succeeds and no one types
anything in the specified number of seconds.
Speed, the optional second argument, is a label to a speed
and tty definition in the file /etc/gettydefs. This
definition tells getty at what speed to initially run, what
the login message should look like, what the initial tty
settings are, and what speed to try next should the user
indicate that the speed is inappropriate (by typing a
<break> character). The default speed is 300 baud.
Type, the optional third argument, is a character string
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GETTY(1M) (Essential Utilities) GETTY(1M)
describing to getty what type of terminal is connected to
the line in question. getty recognizes the following types:
none default
ds40-1 Dataspeed40/1
tektronix,tek Tektronix
vt61 DEC vt61
vt100 DEC vt100
hp45 Hewlett-Packard 45
c100 Concept 100
The default terminal is none; i.e., any crt or normal
terminal unknown to the system. Also, for terminal type to
have any meaning, the virtual terminal handlers must be
compiled into the operating system. They are available, but
not compiled in the default condition.
Linedisc, the optional fourth argument, is a character
string describing which line discipline to use in
communicating with the terminal. Again the hooks for line
disciplines are available in the operating system but there
is only one presently available, the default line
discipline, LDISC0.
When given no optional arguments, getty sets the speed of
the interface to 300 baud, specifies that raw mode is to be
used (awaken on every character), that echo is to be
suppressed, either parity allowed, new-line characters will
be converted to carriage return-line feed, and tab expansion
performed on the standard output. It types the login
message before reading the user's name a character at a
time. If a null character (or framing error) is received,
it is assumed to be the result of the user pushing the
``break'' key. This will cause getty to attempt the next
speed in the series. The series that getty tries is
determined by what it finds in /etc/gettydefs.
After the user's name has been typed in, it is terminated by
a new-line or carriage-return character. The latter results
in the system being set to treat carriage returns
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GETTY(1M) (Essential Utilities) GETTY(1M)
appropriately (see ioctl(2)).
The user's name is scanned to see if it contains any lower-
case alphabetic characters; if not, and if the name is non-
empty, the system is told to map any future upper-case
characters into the corresponding lower-case characters.
Finally, login is exec'd with the user's name as an
argument. Additional arguments may be typed after the login
name. These are passed to login, which will place them in
the environment (see login(1)).
A check option is provided. When getty is invoked with the
-c option and file, it scans the file as if it were scanning
/etc/gettydefs and prints out the results to the standard
output. If there are any unrecognized modes or improperly
constructed entries, it reports these. If the entries are
correct, it prints out the values of the various flags. See
ioctl(2) to interpret the values. Note that some values are
added to the flags automatically.
FILES
/etc/gettydefs
SEE ALSO
ct(1C), init(1M), tty(7).
login(1) in the User's Reference Manual.
ioctl(2), gettydefs(4), inittab(4) in the Programmer's
Reference Manual.
BUGS
While getty understands simple single character quoting
conventions, it is not possible to quote certain special
control characters used by getty. Thus, you cannot login
via getty and type a #, @, /, !, , backspace, ^U, ^D, or &
as part of your login name or arguments. getty uses them to
determine when the end of the line has been reached, which
protocol is being used, and what the erase character is.
They will always be interpreted as having their special
meaning.
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