getty(8) getty(8)
NAME
getty - set terminal type, modes, speed, and line discipline
SYNOPSIS
/sbin/getty [-h] [-t timeout] line [speed [type [linedisc]]]
/sbin/getty -c file
DESCRIPTION
getty is a program that is invoked by init(1M). It is the second pro-
cess in the series, (init-getty-login-shell) that ultimately connects
a user with the UNIX system. It can only be executed by the superuser,
that is, by 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 an 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 in the
command line.
The two files /usr/lib/terminfo and /etc/termtab are then read, to get
the initialization strings and country code for keyload(1M) [97801].
OPTIONS
line 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.
-h If the -h flag is not set, a hangup will be forced by set-
ting the speed to zero before setting the speed to the
default or specified speed.
-t timeout
Specifies that getty should exit if the open on the line
succeeds and no one types anything in timeout seconds.
speed The speed argument is a label to a speed and TTY definition
in the /etc/gettydefs file. This definition tells getty at
what speed to run initially, what the login message should
look like, what the initial TTY settings are, and what speed
to try next, should the user indicate, by pressing the BREAK
key, that the speed is inappropriate. The default speed is
300 baud.
type The type argument is a character string 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
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getty(8) getty(8)
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 termi-
nal unknown to the system. Also, for terminal types to have
any meaning, the virtual terminal handlers must be compiled
into the operating system. They are available, but not com-
piled in the default state.
linedisc The linedisc argument is a character string describing which
line discipline to use when communicating with the terminal.
Again, the hooks for line disciplines are available in the
operating system but only one is presently available, i.e.
the default line discipline LDISC0.
-c file When getty is invoked with the -c option and file, it scans
the file as if it were scanning /etc/gettydefs and sends the
results to 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.
When given no optional arguments, getty specifies the following: The
speed of the interface is set to 300 baud, either parity is allowed,
newline characters are converted to carriage return line feed, and tab
expansion is performed on the standard output. getty types the login
prompt before reading the user's name, one character at a time. If a
null character (or framing error) is received, it is assumed to be the
result of the user hitting 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 newline
or carriage return character. The latter results in the system being
set to handle carriage returns appropriately [see ioctl(2)].
The user's name is scanned to see if it contains any lowercase alpha-
betic characters; if not, and if the name is non-empty, the system is
told to map any future uppercase characters to the corresponding
lowercase characters.
Finally, login is exec'd with the user's name as an argument. Addi-
tional arguments may be typed after the login name. These are passed
to login, which will place them in the environment [see login(1)].
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getty logs all errors via syslogd(1M) using auth.crit.
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 log in 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.
FILES
/etc/gettydefs
/etc/default/login
/etc/termtab
/etc/terminfo
SEE ALSO
ct(1), login(1), init(1M), ioctl(2), gettydefs(4), inittab(4),
login(4), termtab(4), terminfo(4), tty(7).
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