Provided by: util-linux_2.20.1-5.1ubuntu20_amd64 bug


       agetty - alternative Linux getty


       agetty   [-8chiLmnsUw]   [-a   user]   [-f  issue_file]  [-H  login_host]  [-I  init]  [-l
       login_program] [-t timeout] port baud_rate,...  [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

       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   produced   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/gettytab (SunOS 4) files.


       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 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 switching.

       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, --8bits
              Assume that the tty is 8-bit clean, hence disable parity detection.

       -a, --autologin username
              Log  the  specified  user  automatically  in  without  asking  for a login name and
              password. The -f username option  is  added  to  the  /bin/login  command  line  by
              default. The --login-options option changes this default behaviour and then only \u
              is replaced by the username and no other option is added to the login command line.

       -c, --noreset
              Don't reset terminal cflags (control modes). See termios(3) for more details.

       -f, --issue-file 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

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

       -H, --host 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.

       -i, --noissue
              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 preceded by too much text.

       -I, --init-string 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 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).

       -L, --local-line
              Force  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.

       -m, --extract-baud
              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, --skip-login
              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.

       -o, --login-options "login_options"
              Options   that  are passed to the login program.  \u is replaced by the login name.
              The default /bin/login command line is "/bin/login -- <username>".

              Please read the SECURITY NOTICE below if you want to use this.

       -p, --login-pause
              Wait for any key before dropping  to  the  login  prompt.   Can  be  combined  with
              --autologin to save memory by lazily spawning shells.

       -R, --hangup
              Do call vhangup() for a virtually hangup of the specified terminal.

       -s, --keep-baud
              Try  to  keep the existing baud rate. The baud rates from the command line are used
              when agetty receives a BREAK character.

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

       -U, --detect-case
              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-cr
              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.

              Do not clear the screen before prompting for the login name (the screen is normally

              Do not print a newline before writing out /etc/issue.

              By  default the hostname will be printed.  With this option enabled, no hostname at
              all will be shown.

              By default the hostname is only printed until the  first  dot.   With  this  option
              enabled,  the  full  qualified  hostname  by  gethostname()  or  if  not  found  by
              gethostbyname() is shown.

              Output version information and exit.

       --help Output help screen and exit.


       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

       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


       If you use the --login-program and --login-options options, be aware that a malicious user
       may try to enter lognames with embedded options, which then get passed to the  used  login
       program. Agetty does check for a leading "-" and makes sure the logname gets passed as one
       parameter (so embedded spaces will not create yet another parameter), but depending on how
       the  login  binary  parses  the command line that might not be sufficient.  Check that the
       used login program can not be abused this way.

       Some  programs use "--" to indicate that  the  rest  of  the  commandline  should  not  be
       interpreted  as options. Use this feature if available by passing "--" before the username
       gets passed by \u.


       The issue-file (/etc/issue or the file set with the -f option) 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. Same as `uname -s'.

       l      Insert the name of the current tty line.

       m      Insert the architecture identifier of the machine. Same as `uname -m'.

       n      Insert the nodename of the machine, also known as the hostname. Same as `uname -n'.

       o      Insert the NIS domainname of the machine. Same as `hostname -d'.

       O      Insert the DNS domainname of the machine.

       r      Insert the release number of the OS. Same as `uname -r'.

       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 (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 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.


       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 package and is available from