Computer Science


GETTY(1m)                                               GETTY(1m)

NAME
       getty - sets terminal mode, speed, and line discipline

SYNOPSIS
       /etc/getty  [-d  defaults_file]  [-a]  [-h] [-r delay] [-t
       timeout] [-w waitfor] line [speed [type [lined]]]
       /etc/getty -c gettydefs_file

DESCRIPTION
       Getty is the  second  of  the  three  programs  (init(1m),
       getty(1m),  and  login(1m)),  used  by the system to allow
       users to login.  Getty is invoked by init(1m) to:

       1. Open tty lines and set their modes.

       2. Print the login prompt, and get the user's name.

       3. Initiate a login process for the user.

       The actual  procedure  that  getty  follows  is  described
       below:   Initially,  getty parses its command line.  If no
       errors are found, getty scans the defaults file,  normally
       /etc/conf.getty,   to  determine  certain  runtime  values
       (/etc/conf.getty if compiled  with  FSSTND  option).   The
       values in the defaults file (whose compiled-in name can be
       altered with the optional -d defaults_file argument)  take
       precedence to those on the command line.  Getty then opens
       the line for  reading  and  writing,  and  disables  stdio
       buffering.  If an initialization was specified, it is per-
       formed (see LINE INITIALIZATION).

       After the initialization, the line is closed and reopened.
       This time, however, the line is opened in blocking mode so
       that the device is not tied up.  Detection of the  carrier
       signal will allow the line to be opened.

       Next, getty types the issue (or login banner, usually from
       /etc/issue) and login prompt.  Finally,  getty  reads  the
       user's  login  name  and invokes login(1m) with the user's
       name as  an  argument.   While  reading  the  name,  getty
       attempts  to adapt the system to the speed of the terminal
       being used, and also sets certain terminal parameters (see
       termio(7)) to conform with the user's login procedure.

       The  tty  device  used  by getty is determined by the line
       argument.  Getty uses the string /dev/line as the name  of
       the  device  to attach itself to.  Unless getty is invoked
       with the  -h  flag  (or  HANGUP=NO  is  specified  in  the
       defaults file), it will force a hangup on the line by set-
       ting the speed to zero.  Giving -r delay  on  the  command
       line   (or  using  WAITCHAR=YES  and  DELAY=delay  in  the
       defaults file) will cause getty to wait for a single char-
       acter from the line, and then to wait delay seconds before
       continuing.  If no delay is desired, use -r0.   Giving  -w
       waitfor  on  the command line (or using WAITFOR=waitfor in
       the defaults file) will cause getty to wait for the speci-
       fied string of characters from the line before continuing.
       Giving -t timeout on the  command  line  (or  using  TIME-
       OUT=timeout in the defaults file) will cause getty to exit
       if no user name is accepted within timeout  seconds  after
       the login prompt is typed.

       The  speed argument is a label to a entry in the /etc/get-
       tydefs file (see gettydefs(4)).   This  entry  defines  to
       getty  the initial speed (baud rate) and tty settings, the
       login prompt to be used, the final speed and tty settings,
       and  a  pointer  to  another  entry to try should the user
       indicate that the speed is not correct.  This is  done  by
       sending  a  <break>  character (actually sequence).  Under
       certain conditions, a  carriage-return  will  perform  the
       same function.  This is usually the case when getty is set
       to a higher speed than the modem or terminal.  Getty scans
       the  gettydefs  file  sequentially  looking for a matching
       entry.  If no speed was  given  or  the  entry  cannot  be
       found,  the first entry in the /etc/gettydefs file is used
       as a default.  In the event that the gettydefs file cannot
       be  accessed, there is a compiled-in default entry that is
       used.

       The type argument is a string which names the type of ter-
       minal  attached  to  the line.  The type should be a valid
       terminal name listed in the  termcap(7)  database.   Getty
       uses  this  value to determine how to clear the video dis-
       play.  It also sets the environment variable TERM  to  the
       contents of this value.

       The  lined argument is a string describing the line disci-
       pline to use on the line.  The default is LDISC0.

       As mentioned, getty types the login prompt and then  reads
       the  user's  login name.  If a null character is received,
       it is assumed to be the result of the  user  pressing  the
       <break>  key  or  the  carriage-return key to indicate the
       speed is wrong.  This causes  getty  to  locate  the  next
       speed in the series (defined in /etc/gettydefs).

       The  user's  name  is  terminated  by  a  new-line or car-
       riage-return character.  A carriage-return results in  the
       system being set to map those to new-lines (see ioctl(2)).

       The user's name is scanned to  see  if  it  contains  only
       upper-case  characters.   If  so, the system is set to map
       any future upper-case characters into lower-case.

       A check option is provided for testing the gettydefs file.
       When  getty  is  invoked  with  the -cgettydefs option, it
       scans the named gettydefs file  and  prints  out  (to  the
       standard  output)  the  values  it  sees.   If any parsing
       errors occur (due to errors in the syntax of the gettydefs
       file), they are reported.

DEFAULTS FILE
       During   its   startup,   getty   looks   for   the   file
       /etc/conf.getty.line, (or, if it cannot  find  that  file,
       then  /etc/conf.getty),  and  if found, reads the contents
       for lines of the form

            NAME=value

       This allows getty to have certain features configurable at
       runtime,   without   recompiling.    The  recognized  NAME
       strings, and their corresponding values, follows:

       SYSTEM=name
             Sets the nodename value  (displayed  by  @S  --  see
             PROMPT  SUBSTITUTIONS)  to name.  The default is the
             nodename value returned by the uname(3) call.

       VERSION=string
             Sets the value that is displayed by the @V parameter
             (see  PROMPT  SUBSTITUTIONS)  to  string.  If string
             begins with a '/' character, it is assumed to be the
             full  pathname  of  a  file, and @V is set to be the
             contents of that file.  The  default  is  /proc/ver-
             sion.

       LOGIN=name
             Sets  the  name  of  the login program to name.  The
             default is /bin/login  (see  login(1m)).   If  used,
             name  must  be the full pathname of the program that
             getty will execute instead of /bin/login.  Note that
             this  program  is called, as is /bin/login, the with
             the user's name as its only argument.

       INIT=string
             If defined, string is an expect/send  sequence  that
             is used to initialize the line before getty attempts
             to use it.  This string is in a form resembling that
             used  in  the  L.sys  file  of  uucp(1).   For  more
             details, see LINE INITIALIZATION.   By  default,  no
             initialization is done.

       ISSUE=string
             During  startup, getty defaults to displaying, as an
             issue  or  login  banner,  the   contents   of   the
             /etc/issue  file.   If ISSUE is defined to a string,
             that string is typed instead.  If string begins with
             a  '/' character, it is assumed to be the full path-
             name of a file, and that file  is  used  instead  of
             /etc/issue.

       CLEAR=value
             If value is NO, then getty will not attempt to clear
             the video screen before typing the  issue  or  login
             prompts.  The default is to clear the screen.

       HANGUP=value
             If  value is NO, then getty will NOT hangup the line
             during its startup.  This is analogus to giving  the
             -h argument on the command line.

       WAITCHAR=value
             If  value  is YES, then getty will wait for a single
             character from it's line before continuing.  This is
             useful  for modem connections where the modem has CD
             forced high at all times, to keep  getty  from  end-
             lessly chatting with the modem.

       DELAY=seconds
             Used  in conjunction with WAITCHAR, this adds a time
             delay of seconds after  the  character  is  accepted
             before  allowing  getty  to continue.  Both WAITCHAR
             and DELAY have the same effect as specifying -rdelay
             on the command line.  If WAITCHAR is given without a
             DELAY, the result is equal to having said -r0 on the
             command  line.   The  default  is  to not wait for a
             character.

       TIMEOUT=number
             As with the -t timeout command line argument,  tells
             getty to exit if no user name is accepted before the
             number of seconds elapse after the login  prompt  is
             typed.   The  default is to wait indefinetly for the
             user name.

       CONNECT=string
             If defined, string should be an expect/send sequence
             (like that for INIT) to direct getty in establishing
             the connection.  String may be defined  as  DEFAULT,
             which will substitute the built-in string:

                  CONNECT\s\A\r\n

             The \A escape marks the place where the digits show-
             ing the speed will  be  seen.   See  CONNECTION  AND
             AUTOBAUDING for more details.  The default is to not
             perform a connection chat sequence.

       WAITFOR=string
             This parameter is similar to WAITCHAR, but defines a
             string  of  characters to be waited for.  Getty will
             wait until string is  received  before  issuing  the
             login prompt.  This parameter is best used when com-
             bined with CONNECT, as in this example:

                  WAITFOR=RING
                  CONNECT="" ATA\r CONNECT\s\A

             This would cause getty to wait for the string  RING,
             then  expect  nothing,  send  ATA followed by a car-
             riage-return, and then wait for  a  string  such  as
             CONNECT  2400, in which case, getty would set itself
             to 2400 baud.  The default is not to  wait  for  any
             string of characters.

       ALTLOCK=line
             Uugetty  uses  this  parameter  to lock an alternate
             device, in addition to the one it  is  attached  to.
             This  is  for  those systems that have two different
             device names that refer to the same  physical  port;
             e.g.   /dev/tty1A  vs.  /dev/tty1a,  where  one uses
             modem control and the other doesn't.  See  the  sec-
             tion on UUGETTY for more details.  The default is to
             have no alternate lockfile.

       ALTLINE=line
             Getty uses this parameter  to  specify  a  different
             device to use for handling modem initialization.  If
             the WAITFOR option is being used,  WAITFOR  will  be
             done  on this line also.  This is necessary for sys-
             tems that exercise locking between two lines.

       RINGBACK=value
             If value is YES ringback callin is enabled.  This is
             used  in  conjunction  with  WAITFOR  and CONNECT to
             negotiate incoming calls.  The default action is  to
             connect  only  if the line rings one to three times,
             is hung up, and is called back within 60 seconds  of
             the first call.  MINRBTIME and MAXRBTIME specify the
             minimum  and  maximum  time  for  the  second  call.
             INTERRING  specifies  the  maximum  time between two
             successive rings in the  same  call.   MINRINGS  and
             MAXRINGS  specify  the minimum and maximum number of
             rings for the first call.

       SCHED=range1 range2 range3 ...
             Getty uses this line  to  schedule  times  to  allow
             logins.    Each   range  has  the  form  DOW:HR:MIN-
             DOW:HR:MIN.  DOW is the day of the week.  0  =  Sun-
             day,  1 = Monday, ... 6 = Saturday.  HR is the hour,
             and MIN is the minute.  If the  current  time  falls
             into one of these ranges, the INIT sequence (if any)
             is sent and getty continues to  run  until  the  off
             time.   Otherwise,  the  OFF  sequence  is sent, and
             getty sleeps until the on time.

       OFF=string
             This line is identical to the INIT line,  except  it
             is only sent when the line is scheduled to be OFF.

       FIDO=string
             This  line  specifies the path to the FidoNet mailer
             (usually ifcico).  Undefined by default.  When  set-
             ting  up  a FidoNet mailer, you should also set EMSI
             to yes.  When an incoming FidoNet call is  received,
             the  string tsync or yoohoo is passed to the FidoNet
             mailer as the only command line option if two  TSYNC
             or  two  YOOHOO  sequences are received.  If EMSI is
             set to yes, the entire EMSI  string  (starting  with
             the  first asterisk, and up to but not including the
             final carraige return) is passed as the only command
             line option.

       EMSI=value
             If  set  to  yes,  scan  the  input for FidoNet EMSI
             sequences.

       The name of the defaults file can be changed by specifying
       -d  defaults_file  on  the command line.  If defaults_file
       begins with a slash, it is assumed to be a complete  path-
       name  of  the  defaults file to be used.  Otherwise, it is
       assumed to be a regular filename, causing getty to use the
       pathname            /etc/conf.defaults_file.            or
       /etc/conf.defaults_file if compiled  with  FSSTND  compli-
       ance.

PROMPT SUBSTITUTIONS
       When  getty  is typing the issue or login banner (ususally
       /etc/issue), or the login-prompt,  it  recognizes  several
       escape  (quoted)  characters.   When  one  of these quoted
       characters is found, its value is substituted in the  out-
       put produced by getty.  Recognized escape characters are:

       \\    Backslash (\).

       \b    Backspace (^H).

       \c    Placed  at  the  end  of  a  string, this prevents a
             new-line from being typed after the string.

       \f    Formfeed (^L).

       \n    New-line (^J).

       \r    Carriage-return (^M).

       \s    A single space (' ').

       \t    Horizontal tab (^I).

       \nnn  Outputs the ASCII character whose decimal  value  is
             nnn.  If nnn begins with 0, the value is taken to be
             in octal.  If it begins with 0x, the value is  taken
             to be in hexidecimal.

       In  addition,  a  single  backslash  at  the end of a line
       causes the immediately following new-line to  be  ignored,
       allowing continuation lines.

       Also,  certain  @char  parameters  are  recognized.  Those
       parameters, and the value that  is  substituted  for  them
       are:

       @B    The  current  (evaluated at the time the @B is seen)
             baud rate.

       @D    The current date, in MM/DD/YY .

       @L    The line to which getty is attached.

       @S    The system node name.

       @T    The current time, in HH:MM:SS (24-hour) .

       @U    The number of currently signed-on users.  This is  a
             count of the number of entries in the /etc/utmp file
             that have a non-null ut_name field.

       @V    The value of VERSION, as given in the defaults file.

       To  display  a  single  '@'  character, use either '\@' or
       '@@'.

LINE INITIALIZATION
       One of the greatest benefits (in the author's opinion,  at
       least)  is  the  ability  of  getty to initialize its line
       before use.  This will most likely be done on  lines  with
       modems,  not terminals, although initializing terminals is
       not out of the question.

       Line initialization is performed just after  the  line  is
       opened  and  prior to handling the WAITCHAR and/or WAITFOR
       options.  Initialization is accomplished by placing an

            INIT=string

       line in the defaults file.  String is a series of  one  or
       more fields in the form

            expect [ send [ expect [ send ] ] ... ]

       This  resembles the expect/send sequences used in the UUCP
       L.sys file,  with  the  following  exception:  A  carriage
       return is NOT appended automatically to sequences that are
       'sent.'  If you want  a  carriage-return  sent,  you  must
       explicitly show it, with '\r'.

       Getty supports subfields in the expect field of the form

            expect[-send-expect]...

       as  with UUCP.  All the escape characters (those beginning
       with a '\' character) listed in the  PROMPT  SUBSTITUTIONS
       section are valid in the send and expect fields.  In addi-
       tion, the following escape characters are recognized:

       \p    Inserts a 1-second delay.

       \d    Inserts a 2-second delay.

       \K    Sends a .25-second Break.

       \Tnnn Modifies the default timeout (usually 30 seconds) to
             the  value  indicated  by nnn.  The value nnn may be
             decimal, octal, or hexidecimal;  see  the  usage  of
             \nnn in PROMPT SUBSTITUTIONS.

       Note  that  for  these  additional  escape  characters, no
       actual character is sent.

CONNECTION AND AUTOBAUDING
       Getty will perform a chat sequence establish a proper con-
       nection.   The best use of this feature is to look for the
       CONNECT message sent by a modem and set the line speed  to
       the number given in that message (e.g. CONNECT 2400).

       The   for  the  connect chat script is exactly the same as
       that for the INIT script (see LINE  INITIALIZATION),  with
       the following addition:

       \A    Marks  the  spot  where  the baud rate will be seen.
             This mark will match any and all digits 0-9 at  that
             location  in  the script, and set it's speed to that
             value, if possible.

       Autobauding, therefore, is enabled by placing the 0
            CONNECT=CONNECT\s\A

       would match the string CONNECT 1200 and cause getty to set
       it's baud rate to 1200, using the following steps:

       1. Having  matched  the  value 1200, getty will attempt to
          find an entry with the  label  1200  in  the  gettydefs
          file.   If  a  matching gettydefs entry is found, those
          values are used.  If there is no match, then

       2. The gettydefs values currently in use are  modified  to
          use  the  matched  speed  (e.g. 1200).  However, if the
          matched speed is invalid, then

       3. Getty logs a warning message and resumes normal  opera-
          tion.   This  allows  the  practice of toggling through
          linked entries in  the  gettydefs  file  to  behave  as
          expected.

UUGETTY
       Uugetty  has  identical  behavior  to  getty,  except that
       uugetty is designed to create and use the lock files main-
       tained  by  the  UUCP  family (uucp(1), cu(1) and others).
       This prevents two or more processes from having conficting
       use of a tty line.

       When uugetty starts up, if it sees a lock file on the line
       it intends to use, it will use the pid in the lock file to
       see  if  there  is an active process holding the lock.  If
       not, uugetty will remove the lock file and continue.  If a
       valid process is found, uugetty will sleep until that pro-
       cess releases the lock and  then  it  will  exit,  forcing
       init(1m) to spawn a new uugetty.  Once no conflicting pro-
       cess is found, uugetty grabs the line by creating the lock
       file  itself  before  issuing the login prompt.  This pre-
       vents other processes from using the line.

       Uugetty will normally only lock the name of the line it is
       running  on.   On systems where there are two device names
       referring to the same port  (as  is  the  case  where  one
       device  uses modem control while the other doesn't), place
       a line of the form

            ALTLOCK=line

       line in the defaults file.  For instance, if uugetty is on
       /dev/tty1a,  and you want to have it lock /dev/tty1A also,
       use the line ALTLOCK=tty1A in the defaults file.

       While waiting for carrier detect, Uugetty will  check  for
       lockfiles  every  30  seconds.   If  lockfiles  are found,
       uugetty will exit, and init will  respawn  another  getty.
       This  allows  the  modem to be reinitialized after another
       process has used the modem.

FILES
       /etc/conf.getty[.line]
                       Contains the runtime configuration.   Note
                       that              uugetty             uses
                       /etc/conf.uugetty[.line].

       /etc/gettydefs  Contains speed and tty settings to be used
                       by getty.

       /etc/issue      The default issue (or login banner).

       /bin/login      The default login program called after the
                       user's name is entered.

SEE ALSO
       init(1m), login(1m), uucp(1), ioctl(2),  uname(3),  getty-
       defs(5), utmp(5), termio(7)

AUTHOR
       Getty_ps in its current evil form:
       Kris Gleason  <gleasokr@boulder.colorado.edu>

       Original getty_ps:
       Paul Sutcliffe, Jr.  <paul@devon.lns.pa.us>
       UUCP: ...!rutgers!devon!paul

       Autobauding routines adapted from code submitted by
       Mark Keating <...!utzoo!censor!markk>

Release 2.0.7h               2-Nov-95                           1

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