getty(1M) INTERACTIVE UNIX System getty(1M)
NAME
getty - set terminal type, modes, speed, and line discipline
SYNOPSIS
/etc/getty [ -h ] [ -t timeout ] [ -m maparg ] line
[ speed [ type [ linedisc ] ] ]
/etc/getty -c file
DESCRIPTION
The getty command 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 UNIX System.
It can only be executed by the super-user; that is, a pro-
cess 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 the
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.
The -m option specifies that the ttymap(1) command is to be
run with the argument maparg. ttymap sets the terminal
character mappings. Multiple argument words can be passed
to ttymap by enclosing them in quotes. ttymap is run
immediately before the prompt for the user loginname.
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 set-
ting 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 any-
thing 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 defini-
tion tells getty at what speed to initially run, what the
login message should look like, what the initial tty set-
tings are, and what speed to try next should the user indi-
cate 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
describing to getty what type of terminal is connected to
the line in question. getty recognizes the following types:
none default
ds40-1 DATASPEED terminal 40/1
tektronix,tek TEKTRONIX
vt61 Digital Equipment vt61
Rev. 1.2 Page 1
getty(1M) INTERACTIVE UNIX System getty(1M)
vt100 Digital Equipment 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 type 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 condition.
Linedisc, the optional fourth argument, is a character
string describing which line discipline to use in communi-
cating with the terminal. Again, the hooks for line discip-
lines 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 mes-
sage 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 appropri-
ately [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 char-
acters into the corresponding lower case characters.
Finally, login is exec'd with the user's name as an argu-
ment. 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.
Rev. 1.2 Page 2
getty(1M) INTERACTIVE UNIX System getty(1M)
Example
A valid inittab entry is:
00:23:respawn:/etc/getty -m /usr/lib/keyboard/french.map tty00 9600
FILES
/etc/gettydefs
SEE ALSO
ct(1C), init(1M), login(1), uugetty(1M), tty(7).
ioctl(2), gettydefs(4), inittab(4) in the INTERACTIVE SDS
Guide and Programmer's Reference Manual.
BUGS
While getty understands simple single character quoting con-
ventions, it is not possible to quote certain special con-
trol 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.
WARNING
When connecting two computers using a direct connection,
never invoke getty(1M) on the ports of both machines.
Instead, use uugetty(1M).
ADDED VALUE
This entry, supplied by INTERACTIVE Systems Corporation,
contains enhancements to UNIX System V.
Rev. 1.2 Page 3