agetty

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NAME

       agetty - alternative Linux getty


SYNOPSIS

       agetty [-ihLmw] [-l login_program] [-I init] [-t timeout] port baud_rate,... [term]
       agetty [-ihLmw] [-l login_program] [-I init] [-t timeout] baud_rate,... port [term]


DESCRIPTION

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

       agetty  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 par-
              ity, and 8-bit characters with no parity. The  fol-
              lowing  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 produced by Hayes(tm)-compatible modems.

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

       o      Optionally does not display  the  contents  of  the
              /etc/issue file (System V only).

       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/gettytab (SunOS 4) files.


ARGUMENTS

       port   A path name relative to the /dev  directory.  If  a
              "-"  is specified, agetty assumes that its standard
              input is already connected to a tty port and that a
              connection to a remote user has already been estab-
              lished.

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

       baud_rate,...
              A  comma-separated  list of one or more baud rates.
              Each time agetty  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 switching.

       term   The value to be used for the TERM environment vari-
              able. 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  before
              writing  the  login prompt. Terminals or communica-
              tions hardware may become confused  when  receiving
              lots  of  text  at  the  wrong  baud  rate; dial-up
              scripts may fail if the login prompt is preceded by
              too much text.

       -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 charac-
              ters may be sent by writing their octal  code  pre-
              ceded  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  password
              file).

       -m     Try  to  extract  the  baud rate the connect status
              message  produced  by   some   Hayes(tm)-compatible
              modems.  These  status  messages  are  of the form:
              "<junk><speed><junk>".   agetty  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.

       -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 local line with  no  need  for
              carrier  detect.  This  can be useful when you have
              locally attached terminal  where  the  serial  line
              does not set the carrier detect signal.

       -w     Wait  for the user or the modem to send a carriage-
              return or a linefeed character before  sending  the
              /etc/issue file and the login prompt.



EXAMPLES

       This section shows sample entries for the /etc/inittab file.

       For a hard-wired line:
            tty1:con80x60:/sbin/agetty 9600 tty1

       For a dial-in line with a 9600/2400/1200 baud modem:
            ttyS1:dumb:/sbin/agetty -mt60 ttyS1 9600,2400,1200

       These examples assume you use the simpleinit(8) init program for Linux.
       If you use a SysV like init (does /etc/inittab mention "respawn"?), refer
       to the appropriate manual page.



ISSUE ESCAPES

       The /etc/issue file may contain 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 number 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 (System V only).
       /dev/console, problem reports (if syslog(3) is not used).
       /etc/inittab (Linux simpleinit(8) configuration file).


BUGS

       The  baud-rate  detection feature (the -m option) requires
       that agetty 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  combi-
       nation with a multiple baud rate command-line argument, so
       that BREAK processing is enabled.

       The text in the /etc/issue file 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 diagnos-
       tics are written 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 <wietse@wzv.win.tue.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 <poe@daimi.aau.dk>
       Linux port.



CREATION DATE

       Sat Nov 25 22:51:05 MET 1989


LAST MODIFICATION

       91/09/01 23:22:00


VERSION/RELEASE

       1.29
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Copyright (C) 1998 Hurricane Electric. All Rights Reserved.