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NAME

       ngetty - daemon for virtual console terminals

SYNOPSIS

       ngetty [ tty1 | vc/1 | 1 ] [ /dev/tty2 | vc/2 | 2 ] ...
       ngetty-helper /dev/ttyX [ login ]
       ngetty-argv :options:child:[name]:args [user [tty]]

DESCRIPTION

       ngetty  is  a  daemon  that  starts  login  sessions on virtual console
       terminals, on demand.  It opens the virtual console terminals specified
       by  the  tty...   arguments,  displays a /etc/issue message, prints the
       login prompt on each terminal and waits for user name.  On user action,
       ngetty executes login(1) in a new process with the terminal the user is
       typing in as the controlling terminal.

       login(1) then prompts for a password  to  login  with  the  system  and
       finally, if the login succeeds, executes the user's login shell.

       When  the  user  logs  out,  ngetty  restarts the corresponding virtual
       console terminal.

       Actually almost the whole work is done by a ngetty-helper program.   It
       makes   /var/run/utmp,   /var/log/wtmp   records,   prints  /etc/issue,
       hostname, login prompt,  waits  for  user  name.   ngetty  invokes  the
       ngetty-helper by need.

HISTORY

       The traditional way to enable logins on virtual console terminals is to
       start a bunch of  getty(8)  programs,  one  for  each  virtual  console
       terminal,  from init(8).  As most users rarely login on virtual console
       terminals nowadays,  preferring  graphical  logins  instead,  it  seems
       wasteful to have all those getty(8) processes doing nothing but wasting
       memory.  Alternatively, ngetty manages logins on any number of  virtual
       console terminals from a single, light, process.

INVOCATION

       ngetty does not use stdin, stdout or stderr and closes them.

       When running ngetty in the background, remember to disassociate it from
       the current controlling terminal by making it the process group  leader
       of a new session, e.g.:

           setsid ngetty tty...  &
           ngetty-argv :-D:-S:-e:--:/sbin/ngetty::1:2:3:4

       To start ngetty from init(8), add something like this to /etc/inittab:

              ng:2345:respawn:/sbin/ngetty tty1 tty2 ... tty6

       If  ngetty-argv  is available use it to start ngetty from /etc/inittab.
       See the example bellow.

DIAGNOSTICS

       If ngetty can not open one of the virtual console  terminals  specified
       in the tty...  arguments, most likely because that tty device node does
       not exist, no greeting message will  be  displayed  on  that  terminal,
       obviously,  and  ngetty  will  simply  go  on,  ignoring  the offending
       terminal.  Create the missing tty device and send  SIGCHLD  to  ngetty.
       Then  it  will  reopen the new tty.  Instead of sending SIGCHLD you can
       login and logout on some working  tty.   This  also  forces  ngetty  to
       reopen the new tty.

       ngetty  uses ngetty-helper program.  It's path is hard-coded in ngetty.
       Never remove ngetty-helper program nor move it to other location.

       If, on user action, ngetty-helper can  not  execute  login(1),  in  all
       likelihood  because  the  compiled-in  LOGIN  path  does not match your
       system's login(1) path, ngetty restarts the terminal and redisplays the
       greeting message.

       In any case, ngetty does not output error messages.

OPTIONS

       It's  possible  to  set  different options for ngetty-helper program in
       file /etc/ngetty/Conf.  If the option begin with "=" it's  applied  for
       all tty.  If it start with a tty name it's applied only on current tty.
       Examples:

              # options format:
              # [ttyX]=option[=value]
              #=debug
              =environ=,TERM=linux
              tty3=long-hostname
              tty1=clear=c
              =newline=
              =timeout=180
              tty1=timeout=60
              tty1=delay=1

       For security reasons ngetty-helper evaluate the  file  /etc/ngetty/Conf
       only if it has mode:

              -rw-------    root   root   /etc/ngetty/Conf

       ngetty-helper  recognizes the following options which might be embedded
       in the /etc/ngetty/Conf file:

       # tty5=login-prog=/bin/login.test
              If a line starts with #, space or tab it is a comment.

       debug  If debug is set ngetty-helper write on terminal all successfully
              applied  options.  Set this on the fist line of /etc/ngetty/Conf
              file.

       date-string
              Escape \d (current day) in /etc/issue as:
              Fri Jun 01 2007.  Default is: 2007-06-01.

       days=string
              Abbreviation for week days (21 bytes).  Default is:
              =days=SunMonTueWedThuFriSat

       months=string
              Abbreviation for months (36 bytes).  Default is:
              =months=JanFebMarAprMayJunJulAugSepOctNovDec

       tz=string
              Change the timezone offset.  If the  string  starts  with  slash
              it's  the  name of tzfile.  The string is positive number if the
              local time zone is east of the Prime Meridian and negative if it
              is west.  Default is /etc/localtime.  Examples:
              =tz=-18000        -0500
              =tz=7200          +0200
              =tz=/etc/localtime
              =tz=AUTO

       echo-off
              Turn the echo off just before starting /bin/login.  It's similar
              to stty -echo.

       newline=string
              Print this string before writing out  /etc/issue.   (default  is
              
).  Example:
              tty3=newline=
I am \l


       clear=string
              Clear  the  screen  before prompting for the login name with the
              string (default is c).  Examples:
              tty1=clear=
              tty3=clear=

       noclear-first=/etc/ngetty/.noclear
              Do not clear the screen before prompting for the login name  the
              first time after reboot.  Example:
              tty1=noclear-first=/etc/ngetty/.noclear.tty1

       nohangup
              Do  not  call  vhangup() to disable writing to this tty by other
              applications.

       long-hostname
              By default the hostname is only printed  until  the  first  dot.
              With  this  option  enabled, the full text from gethostname() is
              shown.

       nousername
              Do not ask for user name.  Exec login(1) immediately.  Example:
              =nousername
              =login-prompt= Press ENTER to activate \l

       deny=,black,list,users...
              Disable login process for some  users.   The  first  char  after
              "deny=" is split char.  Example:
              tty1=deny=,root,nobody,guest

       allow=,white,list,users...
              Enable  login  process only for the users.  The first char after
              "allow=" is split char.  Example:
              =clear=
              =allow=,root,operator

       print=an:CM:PY:04:69
              Accept only these chars in user name.  Default is to accept only
              ",-._ 0-9 a-z A-Z".  It's possible to insert here the output of
              printf 'tty3=print=az:AZ:\ABC\XYZ:__'
              Here ABC and XYZ are octal numbers.  Examples:
              tty1=print=az:AZ
              tty2=print=az:AZ:__:,.:09

       issue-file=/etc/issue
              Change the issue file.  Disable printing of the issue file with:
              =issue-file=

       login-prog=/bin/login
              Change the login app.  It's possible to use fgetty's /bin/login1
              application with:
              =echo-off
              =login-prog=/bin/login1

       login-buffer=string
              Read login name over the string.  Default  string  is  40  bytes
              long.  Example:
              =login-buffer=12345678901234567

       login-prompt=
 login:
              Change the login prompt string.  Example:
              =login-prompt=\l  
 login:

       nice=10
              Change the priority by calling nice().

       delay=5
              Sleep this many seconds before printing the file /etc/issue.

       timeout=180
              Wait at most this many seconds for user name.

       chdir=/home
              Change into this directory before calling the login prog.

       chroot=/chroot
              Call chroot() with this directory name.

       autologin-name=username
              Log  the  specified  user  automatically in without asking for a
              login name and password.  Check the -f  option  from  /bin/login
              for this.  Example:
              tty1=autologin-name=maria

       autologin-first=/etc/ngetty/.autologin
              Log  in  automatically  only the first time after reboot without
              asking for a login name and password.  Example:
              tty1=autologin-name=maria
              tty1=autologin-first=/etc/ngetty/.autologin

       environ=,TERM=linux
              Replace the environ.  The first char after "environ="  is  split
              char.  Examples:
              =environ=,TERM=vt100,PATH=/bin:/usr/bin,HOME=/
              tty3=environ=,TERM=linux,TTY=/dev/tty3

       sh-A=line
              Exec this line before printing /etc/issue.  The line is executed
              using /bin/sh -c line.  It's good idea to  use  the  full  paths
              here.  Example:
              tty4=sh-A=exec /bin/ps e -u root
              tty4=delay=8

       sh-B=line
              Similar  to  option  sh-A.   This  is executed before asking for
              username.

       login-argv=any_string
              Ngetty starts login application with options
              login -- XYZ      # default
              login -f XYZ      # if autologin-name=XYZ
              With  this  option  it's  possible  to  start  login  appl  with
              any_string  instead  of  --  or  -f.   Using the program ngetty-
              argv(8)  one  can  start  arbitrary   program   with   different
              arguments.  Two very dangerous examples are (never try them):
              tty4=login-prog=/sbin/ngetty-argv
              tty5=login-prog=/sbin/ngetty-argv
              tty4=login-argv=,/bin/login,,-f,%U
              tty5=login-argv=:-C:/bin/bash:-bash

WARNING

       If  ngetty-helper finds stdout or stderr open it exits immediately with
       error 100.  Ngetty invokes it correctly.  See also  the  program  test-
       helper.c in source package.

       Do not edit the file /etc/ngetty/Conf directly.  Put the configurations
       in  /etc/ngetty/Conf.sed  (the   same   syntax   and   permissions   as
       /etc/ngetty/Conf) and after editing it, execute:

              cd /etc/ngetty && ./setup

       The script /etc/ngetty/setup removes comments, merges lines ending with
       a backslash and expands the string =tz=AUTO to numeric number.  Then it
       updates /etc/ngetty/Conf.

SIGNALS

       If  ngetty receives SIGTERM it kill all child's PID (first with SIGTERM
       and then with SIGKILL) and exit immediately.  It does not  change  UID,
       GID  and  mode  of  the controlling tty devices.  It does not catch the
       other signals.  Sending SIGCHLD to  ngetty  forces  it  to  reread  his
       internal cache tables and to restart failed tty devices.

ISSUE ESCAPES

       ngetty-helper recognizes the following escapes sequences which might be
       embedded after  login-prompt=, newline=, clear= or  in  the  /etc/issue
       file:

       \d     insert current day (localtime),

       \l     insert line on which ngetty is running,

       \m     inserts machine architecture (uname -m),

       
     inserts machine's network node hostname (uname -n),

       \o     inserts domain name,

       
     inserts operating system release (uname -r),

       	     insert current time (localtime),

       \s     inserts operating system name,

       \u     insert the number of users which are currently logged in,

       \U     insert  the   string   "1 user" or "<n> users", where <n> is the
              number of users currently logged  in,

            inserts operating system version (uname -v).

       \XYZ   inserts a letter with octal code XYZ.

EXAMPLE

       "Linux eos i386 #1 Tue Mar 19 21:54:09 MET 1996"   was   produced    by
       putting "\s 
 \m " into /etc/issue.

NGETTY-ARGV

       The program ngetty-argv(8) splits argv[1] on strings, expands %U and %T
       to username and tty and then start the the application.  The first char
       after  "login-argv="  is  split char.  In the examples above every user
       logs on tty4 without password and tty5 is always root.   To  understand
       better how ngetty-argv works try as non-root:

       ngetty-argv ':/bin/echo:echo:%U: on %T' usr tty3
       ngetty-argv ':/bin/sleep:-hacker:39:I am %U on %T' 123 X

       One can put also options for ngetty-argv at the beginning.

              --         last option

              -u503      setuid to 503

              -g230      setgid to 230

              -a120      exec alarm(120) before starting child

              -s10       sleep 10 secs before starting child

              -d/X/YZ    chdir(/X/YZ)  before starting child

              -r/A/BC    chroot(/A/BC) before starting child

              -D         start the child in background and exit

              -N -C      NOTTY | SCTTY controlling tty

              -S         like setsid(8)

              -e,HOME=/,TERM=linux     same as environ= above

              -p/path/to/pid.file      write the child pid here

       One possible example for /etc/ngetty/Conf is:
           tty9=clear=
           tty9=issue-file=
           tty9=login-prompt=
  \d 	  qmail-qread:
           tty9=login-prog=/sbin/ngetty-argv
           tty9=login-argv=:-u106:-g503:-d/var/qmail:--
             :./bin/qmail-qread:qread

       Another example is setting the TTY environ automatically:
           =login-prog=/sbin/ngetty-argv
           =login-argv=:-e,TTY=/dev/%T,TERM=linux:--
             :/bin/login:login-%T:--:%U

       I  recommend  using  ngetty-argv   in  /etc/inittab  also.  Put as last
       argument runlevel string.  Then ps will  show  ngetty-2345  instead  of
       ngetty.  Next start tty1 ... tty6 on runlevels 2345.
           ng:2345:respawn:/sbin/ngetty-argv
             .-e.-S.-d/.-s1.--./sbin/%U.%U-%T.1.2.3.4.5.6
             ngetty 2345

       On a terminal (in scripts) start ngetty with
           ngetty-argv .-N.-S.-e./sbin/%U.%U.8.9.10 ngetty
           ngetty-argv .-D.-S.-e./sbin/%U.%U.8.9.10 ngetty

       This  program  is  a  hack  written  for  ngetty-helper.   There  is no
       additional code in ngetty-helper and it's possible to start  a  program
       with  any  args.   It  is like a filter between ngetty-helper and login
       application.  One can easy modify it  without  touching  ngetty-helper.
       It's  similar  to  DJB  well  known argv0(1) and setuidgid(8).  You can
       write own such programs and use them instead of ngetty-argv.

FILES

       /etc/ngetty/Conf        ngetty-helper configuration file
       /etc/ngetty/Conf.sed    private setup file
       /etc/ngetty/setup       updates Conf.sed -> Conf
       /etc/issue              printed before the login prompt
       /var/run/utmp           the system status file
       /var/log/wtmp           the system logging file
       /etc/inittab            init(8) configuration file

SEE ALSO

       getty(8) fgetty(8) mingetty(8)
       login(1) nlogin(1) argv0(1) setuidgid(8) stty(1)
       http://sites.google.com/site/anbadeol/logind

AUTHOR

       Nikola Vladov
       http://riemann.fmi.uni-sofia.bg/ngetty/

COPYRIGHT

       Copyright 2007,2008,2010 Nikola Vladov

       This program is free software; you can redistribute it and/or modify it
       under  the  terms of the GNU General Public License as published by the
       Free Software Foundation; either version 2 of the License, or (at  your
       option) any later version.

       This  program  is  distributed  in the hope that it will be useful, but
       WITHOUT  ANY  WARRANTY;  without   even   the   implied   warranty   of
       MERCHANTABILITY  or  FITNESS  FOR  A  PARTICULAR  PURPOSE.  See the GNU
       General Public License for more details.

                                   May 2010                          NGETTY(8)



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