getty(8) CLIX getty(8)
NAME
getty - Sets terminal type, modes, speed, and line discipline
SYNOPSIS
/etc/getty [-h] [-t timeout] line [speed [type [linedisc]]]
/etc/getty -c file
DESCRIPTION
The getty command sets terminal characteristics. The command is invoked
by init. It is the second process in the series ``init-getty-login-
shell'' that ultimately connects a user with the UNIX system. It can only
be executed by a process with the user ID of root. Initially, getty
displays the login message field for the entry it is using from the
/etc/gettydefs file. The getty command reads the user's login name and
invokes the login 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 flags and arguments
specified.
The line argument is the name of a tty line in /dev to which getty is to
attach itself. The getty command uses this string as the name of a file
in the /dev directory to open for reading and writing. Unless it 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, along with the timeout argument (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.
The speed argument is optional. It is a label to a speed and tty
definition in the /etc/gettydefs file. 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.
The type argument is also optional. It is a character string describing
to getty what type of terminal is connected to the line in question. The
getty command recognizes the following types:
none default
ds40-1 Dataspeed40/1
tektronix
tek Tektronix
vt61 DEC vt61
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getty(8) CLIX getty(8)
vt100 DEC vt100
hp45 Hewlett-Packard 45
c100 Concept 100
The default terminal type is none, meaning 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.
The linedisc argument is a character string describing which line
discipline to use in communicating with the terminal. The hooks for line
disciplines are available in the operating system, but only the default
(LDISC0) is presently available.
When given no optional arguments, getty sets the speed of the interface to
300 baud, and specifies the following characteristics:
⊕ Raw mode is to be used (awaken on every character).
⊕ Echo is to be suppressed.
⊕ Either parity is allowed.
⊕ Newline characters will be converted to carriage return-linefeed.
⊕ Tab expansion will be performed on stdout.
The getty command 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 the /etc/gettydefs file.
After the user's name has been typed in, it is terminated by a newline or
carriage-return character. The latter results in the system being set to
treat carriage returns appropriately (see ioctl(2)).
The user's name is scanned to see if it contains any lowercase alphabetic
characters; if not, and if the name is nonempty, the system is told to map
any future uppercase characters into the corresponding lowercase
characters.
Finally, login is executed 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 flag and
file, it scans the file as if it were scanning /etc/gettydefs and displays
the results to stdout. If there are any unrecognized modes or improperly
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getty(8) CLIX getty(8)
constructed entries, it reports these. If the entries are correct, it
displays 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
/etc/issue
NOTES
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 with getty and type a #, @, /, !, _, backspace, ^U,
^D, or & as part of your login name or arguments. The getty command 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.
RELATED INFORMATION
Commands: ct(1), init(8), login(1)
Files: tty(7), gettydefs(4), inittab(4)
Functions: ioctl(2)
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