unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (Debian-3.1)
Page:
Section:
Apropos / Subsearch:
optional field

AGETTY(8)                   System Manager's Manual                  AGETTY(8)



NAME
       getty - alternative Linux getty


SYNOPSIS
       getty  [-ihLmnw] [-f issue_file] [-l login_program] [-I init] [-t time-
       out] [-H login_host] port baud_rate,...  [term]
       getty [-ihLmnw] [-f issue_file] [-l login_program] [-I init] [-t  time-
       out] [-H login_host] baud_rate,...  port [term]


DESCRIPTION
       getty  opens  a  tty  port,  prompts  for  a login name and invokes the
       /bin/login command. It is normally invoked by init(8).

       getty has several non-standard features that are useful for  hard-wired
       and for dial-in lines:

       o      Adapts  the tty settings to parity bits and to erase, kill, end-
              of-line and uppercase characters when it  reads  a  login  name.
              The  program can handle 7-bit characters with even, odd, none or
              space parity, and 8-bit characters with no parity. The following
              special  characters  are  recognized: @ and Control-U (kill); #,
              DEL and back space (erase); carriage return and line  feed  (end
              of line).

       o      Optionally  deduces the baud rate from the CONNECT messages pro-
              duced by Hayes(tm)-compatible modems.

       o      Optionally does not hang up when it is given an  already  opened
              line (useful for call-back applications).

       o      Optionally does not display the contents of the /etc/issue file.

       o      Optionally   displays  an  alternative  issue  file  instead  of
              /etc/issue.

       o      Optionally does not ask for a login name.

       o      Optionally invokes  a  non-standard  login  program  instead  of
              /bin/login.

       o      Optionally turns on hard-ware flow control

       o      Optionally  forces the line to be local with no need for carrier
              detect.

       This program does not use the /etc/gettydefs (System  V)  or  /etc/get-
       tytab (SunOS 4) files.

ARGUMENTS
       port   A  path  name relative to the /dev directory. If a "-" is speci-
              fied, getty assumes that its standard input is already connected
              to a tty port and that a connection to a remote user has already
              been established.

              Under System V, a "-" port argument  should  be  preceded  by  a
              "--".

       baud_rate,...
              A  comma-separated  list  of  one  or more baud rates. Each time
              getty receives a BREAK character it advances through  the  list,
              which is treated as if it were circular.

              Baud  rates should be specified in descending order, so that the
              null character (Ctrl-@) can also be used for baud  rate  switch-
              ing.

       term   The  value  to  be  used for the TERM environment variable. This
              overrides whatever init(8) may have set,  and  is  inherited  by
              login and the shell.

OPTIONS
       -h     Enable  hardware  (RTS/CTS)  flow  control. It is left up to the
              application to disable software (XON/XOFF) flow  protocol  where
              appropriate.

       -i     Do  not  display  the  contents  of /etc/issue (or other) before
              writing the login prompt. Terminals or  communications  hardware
              may  become  confused  when  receiving lots of text at the wrong
              baud rate; dial-up scripts may fail if the login prompt is  pre-
              ceded by too much text.

       -f issue_file
              Display  the contents of issue_file instead of /etc/issue.  This
              allows custom messages to be displayed on  different  terminals.
              The -i option will override this option.

       -I initstring
              Set  an  initial  string  to  be sent to the tty or modem before
              sending anything else. This may be used to initialize  a  modem.
              Non printable characters may be sent by writing their octal code
              preceded by a backslash (\). For  example  to  send  a  linefeed
              character (ASCII 10, octal 012) write \012.

       -l login_program
              Invoke  the specified login_program instead of /bin/login.  This
              allows the use of a non-standard login program (for example, one
              that  asks for a dial-up password or that uses a different pass-
              word file).

       -H login_host
              Write the specified login_host into the utmp file. (Normally, no
              login  host  is  given,  since getty is used for local hardwired
              connections and consoles. However, this option can be useful for
              identifying terminal concentrators and the like.

       -m     Try to extract the baud rate the CONNECT status message produced
              by Hayes(tm)-compatible modems. These status messages are of the
              form: "<junk><speed><junk>".  getty assumes that the modem emits
              its status message at the same  speed  as  specified  with  (the
              first) baud_rate value on the command line.

              Since  the  -m  feature  may fail on heavily-loaded systems, you
              still should enable BREAK processing by enumerating all expected
              baud rates on the command line.

       -n     Do  not  prompt  the  user for a login name. This can be used in
              connection with -l option to invoke a non-standard login process
              such  as  a BBS system. Note that with the -n option, getty gets
              no input from user who logs in and therefore won't  be  able  to
              figure out parity, character size, and newline processing of the
              connection. It defaults to space parity, 7 bit  characters,  and
              ASCII  CR  (13)  end-of-line character.  Beware that the program
              that getty starts (usually /bin/login) is run as root.

       -t timeout
              Terminate if no user name could be read within timeout  seconds.
              This option should probably not be used with hard-wired lines.

       -L     Force  the  line  to  be  a  local line with no need for carrier
              detect. This can be useful when you have a locally attached ter-
              minal where the serial line does not set the carrier detect sig-
              nal.

       -w     Wait for the user or the modem to send a  carriage-return  or  a
              linefeed character before sending the /etc/issue (or other) file
              and the login prompt. Very useful  in  connection  with  the  -I
              option.

EXAMPLES
       This  section  shows  examples for the process field of an entry in the
       /etc/inittab file.  You'll have to prepend appropriate values  for  the
       other fields.  See inittab(5) for more details.

       For a hard-wired line or a console tty:
            /sbin/getty 9600 ttyS1

       For  a  directly  connected  terminal  without  proper  carriage detect
       wiring: (try this if your terminal just sleeps instead of giving you  a
       password: prompt.)
            /sbin/getty -L 9600 ttyS1 vt100

       For a old style dial-in line with a 9600/2400/1200 baud modem:
            /sbin/getty -mt60 ttyS1 9600,2400,1200

       For  a  Hayes  modem  with a fixed 115200 bps interface to the machine:
       (the example init string turns off modem echo and result  codes,  makes
       modem/computer DCD track modem/modem DCD, makes a DTR drop cause a dis-
       connection and turn on auto-answer after 1 ring.)
            /sbin/getty -w -I 'ATE0Q1&D2&C1S0=1\015' 115200 ttyS1


ISSUE ESCAPES
       The issue-file (/etc/issue or the file set with the -f option) may con-
       tain  certain  escape  codes  to display the system name, date and time
       etc. All escape codes consist of a backslash (\)  immediately  followed
       by one of the letters explained below.


       b      Insert the baudrate of the current line.

       d      Insert the current date.

       s      Insert the system name, the name of the operating system.

       l      Insert the name of the current tty line.

       m      Insert the architecture identifier of the machine, eg. i486

       n      Insert the nodename of the machine, also known as the hostname.

       o      Insert the domainname of the machine.

       r      Insert the release number of the OS, eg. 1.1.9.

       t      Insert the current time.

       u      Insert the number of current users logged in.

       U      Insert  the string "1 user" or "<n> users" where <n> is the num-
              ber of current users logged in.

       v      Insert the version of the OS, eg. the build-date etc.

       Example: On my system, the following /etc/issue file:

              This is \n.\o (\s \m \r) \t

       displays as

              This is thingol.orcan.dk (Linux i386 1.1.9) 18:29:30



FILES
       /var/run/utmp, the system status file.
       /etc/issue, printed before the login prompt.
       /dev/console, problem reports (if syslog(3) is not used).
       /etc/inittab, init(8) configuration file.

BUGS
       The baud-rate detection feature (the -m option) requires that getty  be
       scheduled  soon enough after completion of a dial-in call (within 30 ms
       with modems that talk at 2400 baud). For robustness, always use the  -m
       option  in combination with a multiple baud rate command-line argument,
       so that BREAK processing is enabled.

       The text in the /etc/issue file (or other) and  the  login  prompt  are
       always output with 7-bit characters and space parity.

       The baud-rate detection feature (the -m option) requires that the modem
       emits its status message after raising the DCD line.

DIAGNOSTICS
       Depending on how the program was configured, all diagnostics are  writ-
       ten  to  the  console  device  or  reported via the syslog(3) facility.
       Error messages are produced if the port argument  does  not  specify  a
       terminal  device;  if  there  is  no utmp entry for the current process
       (System V only); and so on.

AUTHOR(S)
       W.Z. Venema <wietseATwzv.nl>
       Eindhoven University of Technology
       Department of Mathematics and Computer Science
       Den Dolech 2, P.O. Box 513, 5600 MB Eindhoven, The Netherlands

       Peter Orbaek <poeATdaimi.dk>
       Linux port and more options. Still maintains the code.

       Eric Rasmussen <earATusfirst.org>
       Added -f option to display custom login messages on different terminals.


CREATION DATE
       Sat Nov 25 22:51:05 MET 1989

LAST MODIFICATION
       96/07/20



                                                                     AGETTY(8)