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mgetty - smart modem getty
mgetty [options] ttydevice [gettydefs]
Mgetty is a ‘‘smart’’ getty replacement, designed to be used with hayes
compatible data and data/fax modems. Mgetty knows about modem initialization,
manual modem answering (so your modem doesn’t answer if the
machine isn’t ready), UUCP locking (so you can use the same device for
dial-in and dial-out). Mgetty provides very extensive logging facilities.
This manpage doesn’t try to detail mgetty setup in detail, it just
lists the most important options. For detailed instructions, see the
info file mgetty.info (mgetty.texi).
Tells mgetty to leave <space> kbytes free on disk when receiving
- -x <debug level>
Use the given level of verbosity for logging - 0 means no logging,
9 is really noisy. The log file is usually
- -s <speed>
Set the port speed to use, e.g. “-s 19200".
- Tells mgetty that it is running on a direct line. UUCP locking
is done, but no modem initialization whatsoever.
- -p <login prompt>
Use the given string to prompt users for their login names. Various
tokens are allowed in this string. These tokens are: @ for
the system name, \n, \r, \g, \b, \v, \f, \t for newline, carriage
return, bell, backspace, vertical tab, form feed, and tab,
respectively. \P and \L will expand to the tty name ("ttyS0").
\Y will give the Caller ID, \I the “CONNECT foobar” string
returned by the modem, and \S will output the port speed. \s,
\m, \V, \R represent the operating system, the hardware name,
the OS version, the OS release. \N and \U give the number of
users currently logged in. \C will be changed into the result
of ctime(), and \D and \T will output the date and time, respectively.
Finally, \<digit> will use digit as octal/decimal/hexadecimal
representation of the character to follow.
The default prompt is specified at compile time.
- -n #
- Tells mgetty to pick up the phone after the #th RING. Default is
- -R <t> Tells mgetty to go into “ringback” (aka “ring-twice") mode. That
means: the first call is never answered, instead the caller has
to hang up after the phone RINGs, wait 30 seconds, and then call
again in the next <t> seconds for mgetty to pick up. If no call
comes, mgetty will exit.
I do not really recommend using this, better get a second phone
line for the modem.
- -i <issue file>
Output <issue file> instead of /etc/issue before prompting for
the user name. The same token substitutions as for the the login
prompt are done in this file.
- Tells mgetty that the modem is to be treated as a DATA modem, no
fax initalization is attempted.
- Tells mgetty that DATA calls are not allowed and the modem
should be set to Fax-Only.
- -C <class>
Tells mgetty how to treat the modem. Possible values for <class>
are “auto” (default, try to find out whether the modem supports
fax), “cls2” (use the class 2 fax command set, even if the modem
supports class 2.0), “c2.0” (use the class 2.0 fax command set),
“data” (data only, exactly as the -D switch).
- -S <g3 file>
If a call comes in and requests fax polling, mgetty will send
the named file. Note: not all fax modems support poll sending.
- -I <fax id>
Use the given fax station ID for fax identification. Not used
for data modems.
- Open the port in blocking mode. Best used in combination with
“-r". This is the default if mgetty is called as getty. You may
want to use this if you want to make use of the two-device /
kernel-locking scheme of the Linux and SunOS operating systems
(/dev/ttyS.. and /dev/cua..). I do not recommend it, it’s just
include for completeness, and to be able to use mgetty as a
full-featured getty replacement.
- Use autobauding. That is, after a connection is made, mgetty
parses the “CONNECT foo” response code of the modem and sets the
port speed to the first integer found after the “CONNECT"
string, “foo” in this example. You need this if your modem
insist on changing its DTE speed to match the line speed. I recommend
against using it, better leave the port speed locked at a
fixed value. The feature is included because there exist old
modems that cannot use a fixed (locked) port speed.
- -m ‘expect send ...’
Set the “chat sequence” that is used to initialize the modem.
For an empty expect part, use empty double quotes (""). Since
the sequence contains spaces, you have to enclose all of it in
single quotes(’’). Example:
mgetty -m ‘"” ATH0 OK’
Main configuration file.
controls whether (and when) mgetty should call some other program
for user login instead of /bin/login. How this is done is
explained in this file.
controls acceptance/denial of incoming calls based on the
caller’s number. Available only if you have “caller ID” and
your modem supports it.
controls whether mgetty should pick up the phone upon incoming
calls. If the file exists, calls are completely ignored. You can
use this, for example, to stop mgetty during day time, and let
it pick up at night only, by creating and removing /etc/nologin.ttyxx
via the cron program at the appropriate time.
will be printed after a connection is established, and before
the with the ‘-i’ option.
Debug log file, see below.
If mgetty doesn’t work the way it should, the main source of diagnostic
data is the log file. It can be found in “/var/log/mgetty.ttyxx” (for
the mgetty process handling “ttyxx"). If it doesn’t contain enough
details, enhance the log level with the ‘-x’ option to mgetty, e.g. “-x
Many of the common problems and solutions are discussed in the mgetty
manual and the FAQ. Please see the WWW page at http://alpha.greenie.net/mgetty/
Not all of mgetty configuration can be done at run-time yet. Things
like flow control and file paths (log file / lock file) have to be configured
by changing the source and recompiling.
Users never read manuals...
mgetty is Copyright (C) 1993 by Gert Doering, <firstname.lastname@example.org>.
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