One thing I would suggest doing is STOP USING /DEV/MODEM. That is a bad
idea for a couple security reasons (although they are not BIG concerns on
a single-user machine).
It may also be possible that using a symlink to your actual ttyS device is
causing some of your problems. Perhaps you're getting extra lock files or
something.
Try using /dev/ttyS0 (or whichever device your modem uses) instead of
/dev/modem.
First thing I do after installing Linux is delete /dev/modem, /dev/mouse,
and /dev/cdrom. :-)
On Sat, 24 Jul 1999, Hal Burgiss wrote:
>
> This may be long, and may be boring to most, so I apologize in advance.
>
> I have been hanging out on this list because of a modem related problem
> I developed after upgrading from RH5.1 to 6.0. The best I can tell, no
> one else is having this problem so it must be caused by curious
> combination of factors. The problem is also sporadic so has been a
> little hard to get a grip on, but essentially I wind up with a
> completely dead modem. Chat hangs at the first reference to /dev/modem
> eg, '' ATZ. Substitute anything you want for ATZ. statserial hangs,
> stty /dev/modem hangs, echo AT > /dev/modem from bash prompt hangs. The
> last one gives a 'bash: interrupted system call' when terminated with
> CTRL-C. Using all RH updates. pppd is ppp-2.3.7-2, also tried 2.3.8-1.
> Kernel is 2.2.5-22.
>
> The only way back to a sane modem is either reboot or start minicom
> letting it initialize the modem and then exit *without* resetting. This
> always works. I presume minicom is doing its thing at a lower level and
> is thus bypassing whatever is flaky at the user level. The modem also
> works fine if I use dosemu with a DOS comm program there, even if the
> modem is simultaneouly hung in linux. I think this pretty much
> eliminates a possible hardware problem.
>
> While this scenario can occur randomly it is much more likey to occur
> after a dropped connection or if pppd fails to establish a connection.
> In fact, I would say pretty much everytime here I'll get a lifeless
> modem. It does, however, occasionally occur even after a routine
> ppp-down, but is much less likely in this case. Another factor may be
> noisy phone lines that I am forced to deal with here. I regularly have a
> tough time getting a reliable connection. So maybe this is a little more
> of an annoyance to me than someone that has the good fortune to not have
> to deal with this. Perhaps this is a factor either directly or
> indirectly. Dunno.
>
> The reason I am digressing here is that I feel there is an obscure bug
> somewhere but am not exactly sure where and probably I should report it
> but don't know to whom. Have no idea whether this is pppd not returning
> modem to a sane state, or whether it is something else in the OS that
> pppd is relying on. If the later, how to hunt this down? Should I even
> worry about it? Maybe something isolated to RedHat?
>
> FWIW, this snippet gives me back access to modem when it is hung:
>
> ==========================================================
>
> int main(void)
> {
> minp = open("/dev/modem", O_RDWR | O_NOCTTY | O_NONBLOCK);
> if(minp < 0) {
> perror("cannot open /dev/modem");
> return EXIT_FAILURE;
> }
>
> retval = tcgetattr ( minp, &old_termios);
> if(retval != 0) {
> perror("cannot use tcgetattr");
> return EXIT_FAILURE;
> }
>
> old_termios.c_cflag = old_termios.c_cflag | CLOCAL;
>
> retval = tcsetattr( minp, TCSAFLUSH, & old_termios );
> if(retval != 0) {
> perror("cannot use tcsetattr");
> return EXIT_FAILURE;
> }
>
> close(minp);
> return EXIT_SUCCESS;
>
> }
>
> =============================================================
>
> I am not nearly smart enough to come up with this. It is courtesy of
> Mark Gray who I happened into on the RH mailing list. Thanks Mark!
>
> While I can now access the modem after running this bit, pppd will
> consistently fail to connect. If I pump a saved version of 'stty -g'
> back through stty, then all is well again. ;) (This idea also from
> Mark.)
>
> Would appreciate feedback from anyone who thinks this is a problem worth
> reporting and to whom.
>
>
> PS -- Please don't think I am complaining. I am very grateful for all
> the wonderful goodies Open Source has brought us! If nothing else, maybe
> this will help someone else down the line.
>
>
> --
> Hal B
> [EMAIL PROTECTED]
> --
> Linux helps those who help themselves
>
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>
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