3. faxAs well as Internet, you need to send and receive FAX's. Here's how you send high resolution faxes. You can do this even if you don't (yet) have an Internet account. Your modem has to act as a receptionist for incoming calls. DATA gets the login prompt, FAX gets the FAX_machine software. VOICE makes it more complicated. The receptionist must also allow outgoing calls! This is the job of 'getty', a program that converts
serial lines to usable login tty lines. You don't need
mgetty, efax is OK. Most remote fax machines run at 9600. PC FAX modems run at twice that (14400), but no-one seems to have them. You will also need a viewer such as
Later I thought I'd go for mgetty. It does audio? |
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This is a tiny system at 82K, mgetty weighs 444K (uncompiled).
It builds and installs out of the box. You have to customise ONE file - to set your station-id and other parameters.
You have to
Have a look at the main section on getting your modem working, the most basic thing is to know which serial port UART it is connected to, and which IRQ it uses. Once the hardware is working you can move on to the software. The efax and mgetty programs know about different modem capabilities, from different manufacturers.
Run the fax test command to check, and remember that
Unix is a modular system, if the hardware isn't configured
properly the application software (fax) can't use it.
You also have to have permission to use the phone (modem device), so either login as root, or create a phone group with yourself as a member.
vi /usr/bin/fax and make at least these changes ...
The VIEWCMD you use, depends on which fax viewer you prefer.
Remember that FAX images are HUGE, and you need one that scrolls
nicely. xloadimage is a nice simple (direct) viewer.
viewfax has multiple zoom levels, and can 'page' several files.
They should be on your CDROM and on sunsite.
The fax test command, will look at your modem, to see that
all is OK. It's how you know that the correct device is being
used, that it's switched on, and it is a valid FAX modem.
When sending FAXES (and when typing them in your letters) Avoid spaces in the phone number, use dashes! It's confusing with shell. HINT: Help others use CUT+PASTE by using dashes in your EMAIL's and WEB pages. It's so much easier :-)
At first glance, the fonts used in faxes seem quite horrific. This is a problem with the viewer scaling down the image to the display. You will see the difference.
It's mostly all done, you just need to print the faxes, or email a message to someone (the files remain in /var/spool). Delete files when ??
Basically you have three choices: you configure efax to act as a getty (or mgetty) -or- you set efax running when you expect a call -or- you get efax to answer a ringing call.
When efax receives a fax, it puts it in /var/spool/fax, you can customise your system to do something intelligent, like send you an email, or print it out.
The fax view FileName commamd firstly converts the text or the
postscript file to g3 pixel images called FileName.001,
then it calls efix to convert the g3 files so that
xv or xloadimage can view them.
When you have a pixel image, either ready for sending, or just received, you want to look at it, to see that it is OK. If you have a 'real' fax machine (as in real slow, they're all 9600 not 14400), simply send it and look.
The answer is to use xloadimage or viewfax (or something else) but before I found the best, I had to do some experimenting to see. Here are a few things you can try, just for the sake of something to do ;-)
See alse viewfax, and the utilities with mgetty.
efax(1) comes with efix(1), a convertor tool. There are others in the netpbm distribution, and also in the mgetty+sendfax compendium of add-ons. It can convert to different formats, which may or may not please you.
Do these experiments in the /tmp directory, and
delete them later. You should have your own
fax_out.001 from the above commands.
efix -o pbm -n fax_out.pbm fax_out.001
This converted the 20k g3 file, to a 500k pbm. If you don't want to collect lots of .pbm files, you can use the .pbm file format, but don't store it on disk, just pipe it to your preferred viewer's stdin.
xv displays the 1728 x 2287 pbm in a 'lossy' way, the g3 file is OK, the pmb file is OK, the xv display is fuzzy. XV refuses to display huge images at full size, (to scroll them), so it shrinks them.
This shows that the fonts are crystal clear, which may be too high a resolution for the viewer. Unfortunately I couldn't get xloadimage to read the fax_out.001 file directly, it said the format was not recognised. ie the efix program is needed to convert the file formats. (That's what happens when you call /usr/bin/fax view, and it calls xloadimage)
The same effect happens when efix outputs a .pgm. Its because everbody's library code decimates by 4 (half width, half height) and in the process it doesn't know whether to preserve '0's or '1's and the library code drops pixels and lines somewhere.
This is the hottest FAX viewer in town!
Actually, it isn't, the viewfax utility is much more convenient, as it can move between more than one page, and zoom in and out using the mouse, however it is a custom tool, whereas efix and xloadimage are raw tools. Look in the mgetty collection of support utilities for other options.
This file is a mere 250 K, and the display is worse, it is probaby due to the resolution having taken groups of 4 pixels into grey scales.
/usr/bin/fax view uses pgm as default, this saves switching screen res, but pbm is more readable, albeit bigger than the screen. To avoid creating lots of big .pbm files, I edit /usr/bin/fax to use xloadimage, with the .pbm data travelling through a unix pipe, but not getting stored on the disk.
First you have to create your file, probably using a wordprocessor and postscript output to disk. I used Raven-Issue-One.dvi. You can use netscape to convert .html to .ps, or ghostview, or whatever.
Converted ssr01.dvi to ssr01.ps. And much quicker than I expected.
With X11 running, this confirmed that the file is a valid postscript file, and preview it for formatting problems.
created ssr01.ps.052 ie one page per file in g3
format. Typically 50K each.
This is a high res fax viewer.
Hopefully that worked.
If it broke half way, simply delete (mv) the pages that worked ok, and
use the fax_out.ps.0?? wildcard to select those that remain.
Note that the shell expands the wildcard into multiple names
on the command line, so you could just name the file-pages you
want, the fax command looks at each parameter word and sends it,
but the page-9-of-50 will be all wrong (presumably your document
has it's own page numbers, the transmission page number is just
an extra).
FAX has two different vertical reolutions (horizontal is a fixed 204 dpi, vertical can be doubled, and page length depends on the machine and paper).
HI-RES 204 x 196 1728 x 2100 # page length arbitrary LO-RES 204 x 96 1728 x 1000 # eg A4, legal, other
According to the /usr/bin/fax script, HI-RES is the default. Just to prove a point try adding the -l after fax make, then view as above.
If you also find that the default .pgm files are unacceptable for detail/readability, you can make .pbm your default viewer, by editing the /usr/bin/fax script.
Of course when the xxx2pgm library is fixed, you may wish to change it back.
Whilst playing, look in
/usr/lib/ghostscript/examples for pages to convert,
view or even send. fax make converts
plain text itself (useful for a new-built system) but
for postscript files, it calls ghostscript to do
the conversion. This shows how colour pictures
get converted, and how pgm is OK for graphics, but
not for text.
Normally you use ghostview to view postscript files. Using faxview instead is just an experimental toy, to show you how ghostscript gets used automatically.
This untars to it's own relative dir. It's got it's own license. All the docs are in (or start at) ./doc/mgetty.texti-in, including documentation for packages such as voice support.
Basically you have many options to configure, either in /etc/inittab, or pre-compiled into the binary.
mgetty is probably better for incoming calls, especially for 24-hour sites with caller-id or even a voice-modem, but it can generate a lot of log-files, and be a bit much to configure in a hurry. efax if nice for light use at home.