agetty man page on Scientific

Man page or keyword search:  
man Server   26626 pages
apropos Keyword Search (all sections)
Output format
Scientific logo
[printable version]

AGETTY(8)							     AGETTY(8)

       agetty - alternative Linux getty

       agetty  [-8ihLmnUw]  [-f	 issue_file]  [-l login_program] [-I init] [-t
       timeout] [-H login_host] port baud_rate,...  [term]
       agetty [-8ihLmnw] [-f issue_file]  [-l  login_program]  [-I  init]  [-t
       timeout] [-H login_host] baud_rate,...  port [term]

       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 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).	 See also --erase-chars and --kill-chars options.

       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

       o      Optionally does not ask for a login name.

       o      Optionally invokes  a  non-standard  login  program  instead  of

       o      Optionally turns on hard-ware flow control

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

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

       port   A	 path  name relative to the /dev directory. If a "-" is speci‐
	      fied, agetty assumes that its standard  input  is	 already  con‐
	      nected  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

	      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  switch‐

       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.

       -8     Assume  that the tty is 8-bit clean, hence disable parity detec‐

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

       -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.

       -E     If -H fakehost option is given then -h fakehost options is added
	      to the the /bin/login command line.

       -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 agetty is used for local hardwired
	      connections and consoles. However, this option can be useful for
	      identifying terminal concentrators and the like.

       -L [=mode]
	      Control  CLOCAL line flag, the optional argument mode is 'auto',
	      'always' or 'never'.  If the mode argument is omitted  then  the
	      default  is  'always'.  If the -L option is ommitted at all then
	      the default is 'auto'.

	      The mode 'always' forces the line to be a	 local	line  with  no
	      need  for	 carrier  detect.   This can be useful when you have a
	      locally attached terminal where the serial line does not set the
	      carrier detect signal.

	      The  mode	 'never' explicitly clears CLOCAL flags from line set‐
	      ting and the carrier detect signal is expected on the line.

	      The mode 'auto' (agetty default) does not modify CLOCAL  setting
	      and follows the setting enabled by kernel.

       -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>".   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.

       -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, agetty 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 agetty 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‐

       -U     Turn on support for detecting an uppercase only terminal.	  This
	      setting  will  detect  a	login name containing only capitals as
	      indicating an uppercase only terminal and turn on some upper  to
	      lower  case  conversions.	 Note that this has no support for any
	      unicode characters.

       -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

       --erase-chars string
	      This  option  specifies  additional  chars that should be inter‐
	      preted as a backspace (ignore previous char) when user specifies
	      login  name. The default is ´#´, specify empty string to disable
	      the default.

       --kill-chars string
	      This option specifies additional chars  that  should  be	inter‐
	      preted as a kill (ignore all previous chars) when user specifies
	      login name.  The default is ´@´, specify empty string to disable
	      the default.

       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/agetty 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/agetty -L 9600 ttyS1 vt100

       For a old style dial-in line with a 9600/2400/1200 baud modem:
	    /sbin/agetty -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/agetty -w -I 'ATE0Q1&D2&C1S0=1\015' 115200 ttyS1

       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 NIS domainname of the machine.

       O      Insert the DNS 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 (Linux i386 1.1.9) 18:29:30

       /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.

       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 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.

       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.

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

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

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

       The agetty command is part of the util-linux-ng package and is avail‐
       able from


List of man pages available for Scientific

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
Vote for polarhome
Free Shell Accounts :: the biggest list on the net