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1994-05-26
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efax - send/receive faxes using Class 1 or 2 fax modems
[ ] [ | ]
Where _o_p_t_i_o_n_s are:
use the fax modem connected to device _d_e_v. The default is
/dev/fax.
use option _o_p_t to accommodate a non-standard fax modem protocol.
See the MODEM REQUIREMENTS section below for more details. The
_o_p_tions are:
1 Use Class 1 fax modem commands. The modem must suport
Class 1 commands. The default is to use Class 2 commands.
a use software adaptive answer method. If the first attempt
to answer the call does not result in a data connection within 20
seconds the phone is hung up temporarily and answered again in
fax mode (see "Accepting both fax and data calls" below).
e ignore errors in modem initialization commands. If errors
are already being ignored, pay attention to them again.
r reverse bit order during data reception. Most modems re-
quire this option.
x send XON (DC1) instead of DC2 to start data reception. Ap-
plies to Class 2 only.
z delay an additional 100 milliseconds before each modem ini-
tialization or reset command. The initial delay is 100 ms. For
example, -ozzz produces a 400 ms delay.
send the command AT_s_t_r to the modem to initialize it. Multiple
-i may options be used.
send the command AT_s_t_r to the modem to reset it when done. Mul-
tiple -z may options be used.
set the local capabilities to _c_a_p_s. See the section on capabili-
ties below for the format and meaning of _c_a_p_s. The default is
1,3,0,2,0,0,0,0. For Class 2 operation this option must appear
after the modem initialization (-i) option that enables fax mode.
set the local identification string to _i_d. _i_d should be the lo-
cal telephone number in international format (for example "+1 800
555 1212"). This option must appear after the modem initializa-
tion (-i) option that enables fax mode.
select types of messages to be printed. Each _l_o_w_e_r-_c_a_s_e letter
in _s_t_r_n_g enables one type of message:
e - errors
w - warnings
i - session progress information
n - capability negotiation information
c - modem (AT) commands and responses
h - HDLC frame data (Class 1 only)
m - modem output
a - program arguments
r - reception error details
The default is "ewin".
use UUCP-style lock file _l_k_f to lock the modem device before
opening it. If the device is locked, efax checks every 15
seconds until it is free. Up to 16 -x options may be used if
there are several names for the same device. A `#' prefix on the
file name creates an HDB-style (text) lock file.
remove lock file(s) after initializing the modem. This allows
outgoing calls to proceed. When efax detects modem activity it
will attempt to re-lock the device. If the modem is now locked
by another program efax will exit and return 1 (``busy''). If
efax is run again (e.g. by init) it will then wait until the line
becomes free.
don't issue an answer (ATA) command before starting to receive a
fax. Use this option when the modem is set to auto-answer (using
S0=_n) or if another program has already answered the call.
if a CONNECT (or DATA) response indicates a data call, the shell
/bin/sh is exec(2)'ed with _c_m_d as its command. _c_m_d is a
printf(3) format that may contain up to 6 %d escapes which are
replaced by the baud rate following the most recent CONNECT mes-
sage. _c_m_d typically exec's getty(8).
ask for page retransmission if more than _n errors detected, De-
fault is 10.
answer phone and receive a fax. Each fax page is stored in a
separate file. The file name is created using _p_a_t as a
strftime(3) format string. A page number of the form .001, .002,
... is appended to the file name. If _p_a_t is blank (""), a de-
fault string of "%m%d%H%M%S" is used. If a file already exists,
efax terminates with an error message.
dial telephone number _n_u_m and send the fax image files _f_i_l_e....
The telephone number _n_u_m is a string that may contain any dial
modifiers that the modem supports, for example, a T prefix for
tone dialing or commas for delays.
Each page is stored in a separate file. The images are coded ac-
cording to the ITU-T (CCITT) Group 3 fax standard, T.4. The EX-
AMPLES section below shows how Ghostscript and the PBMPlus utili-
ties can be used to create and print these files.
The operating system must provide short response times to avoid
protocol timeouts. When using Class 1 modems the program must
respond to certain events (DCS frame or end of data) within 55
milliseconds. For Class 2 modems the delay should not exceed 1
or 2 seconds.
The operating system must also provide sufficient low-level
buffering to allow uninterrupted transfer of data from the modem
to a disk file at the selected baud rate, typically 9600 bps.
Since the fax protocol does not provide end-to-end flow control
the effectiveness of flow control while receiving is limited by
the size of the modem's buffer. This can be less than 100 bytes.
Efax does not use flow control during reception.
"Group" describes the protocol used to send faxes over the tele-
phone network. Efax suports the universal Group 3 standard. The
"Class" is the protocol used between a computer and a fax modem.
Efax supports Class 1 and 2 (but not 2.0) fax modems.
Most modems (including those based on Rockwell or Sierra chip-
sets) reverse the bit order (MSB to LSB) on receive. This will
cause errors when trying to display or print the received files.
The -or option should be specified when receiving faxes using
these modems.
While all fax modems support XON/XOFF flow control, most have un-
reliable hardware (RTS/CTS) flow control in fax mode. Since
XON/XOFF flow control adds very little overhead in fax mode, efax
does not support hardware flow control.
While some modems have serial buffers of about 1k bytes, many
inexpensive modems have buffers of about one hundred bytes and
are thus more likely to suffer overruns when receiving data.
Some modems may need a delay between commands of more than the
default value used by efax (100 milliseconds). If the delay is
too short, commands may not echo properly, may time out, or may
give inconsistent responses. Use one or more -oz options to in-
crease the delay between modem initialization commands.
Class 1 modems should not be used on systems that cannot guaran-
tee that the program will respond to incoming data in less than
55 milliseconds. Longer delays may cause the fax protocol to
fail in certain places (between DCS and TCF or between RTC and
MPS).
By default efax sends DC2 to start the data flow from the modem
when receiving faxes from Class 2 modems. A few older modems re-
quire XON instead. Use of DC2 would cause the modem to give an
error message and/or the program to time out. The -ox option
should be used in this case.
A few older Class 2 modems don't send DC2 or XON to start the
data flow to the modem when sending faxes. After waiting 2
seconds efax will print a warning and start sending anyways.
The following modems have been reported to work with efax: AT&T
DataPort, ATT/Paradyne, Boca modem, Cardinal Digital Fax Modem
(14400) (Class 1), Crosslink 9614FH faxmodem, FuryCard DNE 5005,
Intel 14.4 fax modem, MultiTech 1432MU, Practical Peripherals
PM14400FXMT, Supra V32bis, Supra Faxmodem 144LC (Class 1), Tele-
bit Worldblazer, Twincom 144/DFi, Vobis Fax-Modem (BZT-approved),
Zoom VFX14.4V (Class 1 and 2), ZyXEL U-1496E[+].
Modem initialization commands are supplied as command-line argu-
ments.
The modem must be set up to issue verbose(text) result codes.
The following command does this:
respond to commands with verbose result codes
The following commands may be useful in some cases:
don't wait for dial tone before dialing. This may be used to
send a fax when the call has already been dialed manually. In
this case use an empty string ("") as the first argument to the
-t command. Use X4 (usual d