getty(8) System Manager's Manual getty(8)
Name
getty - set terminal mode
Syntax
/etc/getty [ type ] [ tty ]
Description
The routine is one of several ( ) by which users gain access to the ULTRIX system from a terminal. The routine initializes a terminal
line, reads a login name, and invokes While reading the name, the routine tries to adapt the system to the speed and type of terminal on
the line specified by the argument.
The command typically invokes as directed by the command field in the file.
The routine first tries to initialize the line. It examines and sets up the line for local or remote connections, as appropriate. Next,
the routine calls to revoke access to the terminal by any background processes that could have open. The routine then opens for reading
and writing. File descriptors 0, 1, and 2 become the standard input, output, and diagnostic devices. If the terminal line is connected to
a modem, the open is not completed until someone dials up and establishes carrier on the channel.
If a terminal exists, but an error occurs when trying to open the terminal, the routine writes a message to the system console. The mes-
sage is repeated every 10 minutes until the terminal is available, or the entry for the terminal is modified to indicate that the terminal
is off, and is notified by a hangup.
The routine checks every minute to see if the terminal is still off.
Next, the routine reads a login name, terminated by a newline or carriage-return character. For a carriage return, the system is set to
treat carriage returns appropriately. For further information, see
The routine scans the user's name to see if it contains any lowercase alphabetic characters. If it does not, and the name is nonempty, the
system is told to map any future uppercase characters into the corresponding lowercase characters.
Finally, calls with the user's name as an argument.
Most of the default actions of can be changed with a suitable table.
The routine can be set to timeout after some interval with the to variable in the table. Thus, if the user does not enter a login name
after a reasonable amount of time, hangs up the dialup line.
Arguments
tty The special device file in the directory to open for the terminal (for example, ttyh0). If there is no argument or the argument is
"+", the terminal line is assumed to be open as file descriptor 0.
type Used to make treat the line specially. This argument is used as an index into the database, to determine the characteristics of the
line. If there is no argument, or there is no such table, the default entry in is used. If there is no a set of system defaults is
used.
The entry is used to define specific terminal hardware attributes such as the baud rate and number of bits per character. Terminals
which are setup to transmit and receive 8-bit characters must specify a gettytab entry which appropriately sets up the line. For
example a terminal line setup to operate at 9600 baud with 8-bit characters may use the "8bit.9600" gettytab entry. If a terminal
is setup to use 8-bit characters, but uses a 7-bit gettytab entry (such as "std.9600") the output from the getty program may be cor-
rupted. This output corruption appears as multinational characters being generated by or programs. When these programs operate in
7-bit mode, the high order bit of the character is used as software provided parity. This parity generation causes conventional
ASCII characters to be transformed into multinational characters. By using an 8-bit gettytab entry, characters will be transmitted
without any software generated parity.
If indicated by the table located, will clear the terminal screen, print a banner heading, and prompt for a login name. Usually
either the banner or the login prompt will include the system hostname. Then the user's name is read, a character at a time. If a
null character is received, it is assumed to be the result of the user pushing the break (interrupt) key. The speed is usually then
changed and the ``login:'' prompt is displayed again. a second break changes the speed again and redisplays the ``login:'' prompt.
Successive break characters cycle through some standard set of speeds.
Diagnostics
The uses to produce diagnostic messages. Therefore, the syslog configuration file will determine where the messages are printed. For fur-
ther information, see
getty: tty: cannot open
A terminal which is turned on in the file cannot be opened. This is probably because the requisite lines are either not configured into the
system or the associated device was not attached during boot-time system configuration. The syslog error logging level is LOG_ERR.
getty: command, tty failing, open blocked
The routine tried a non-blocking open of the terminal line and the open still blocked. This can only happen on devices that have not
implemented O_NDELAY. For further information, see The routine tries to continue but the line may not be properly initialized. The syslog
error logging level is LOG_ERR.
getty: command, tty open failed, reason
The routine tried a non-blocking open of the terminal line and the open failed. The reason is the explanation produced by the routine for
why the open failed. The routine tries to continue but the line may not be properly initialized. The syslog error logging level is
LOG_ERR.
getty: in use line tty
The Itty is in use by some other process. The routine will not initialize a line that is already in use. The routine will block until the
line is no longer in use. See and for discussions on shared lines. The syslog error logging level is LOG_INFO.
getty could not set pgrp, reason
The routine tried and failed to initialize the process group of the terminal to process group 0. See for a discussion of process groups.
The reason is the explanation produced by for the failure. The syslog error logging level is LOG_INFO.
Files
Data base describing terminal lines
See Also
login(1), tty(4), gettytab(5), ttys(5), init(8), syslog(8)
getty(8)