Very Computer

Hi,

making my first steps in programing linux in c (after reading some books and
howto's) i wonder which would be the common (best) way to print text to a
printer.

I would prefer to print to the printer in the same way I print to stdout
(using printf or puts), but I don't want to use the '/dev/lp'-file because
of the fact that a non-root-user could not access it and I dont want to
completly redirect stdout as the program prints to both the display and the
printer.
I would be happy if i could pass the text to the lpd and let it handle the
rest, but generating a file on the disk and printing it via the lpr-command
seems unprofessional to me.

It would be great if someone could give me some helping words or even a
short code-example.

Brar

  #include <stdio.h>

  FILE *printer;

  if ((printer = popen("/usr/bin/lpr","w")) == NULL)
  {
        int count;

        fprintf(printer,"This is a print test.\n");
        for (count = 2; count < 102; ++count)
             fprintf(printer,"This is line %d\n",count);
        fprintf(printer,"This ends the print test\n");
        pclose(printer);
  }
  else fprintf(stderr,"Gak!! cant popen(\"/usr/bin/lpr\")\n");

Lew Pitcher
Information Technology Consultant
Toronto Dominion Bank Financial Group

(Opinions expressed are my own, not my employer's.)

Correction......

   /* *** CORRECTION ***
   ** if ((printer = popen("/usr/bin/lpr","w")) == NULL)
   */

   if ((printer = popen("/usr/bin/lpr","w")) != NULL)  

Lew Pitcher
Information Technology Consultant
Toronto Dominion Bank Financial Group

(Opinions expressed are my own, not my employer's.)

Hi Lew,

thank you very much for your code sample, it was exactly what i was lloking
for - short, easy to understand and fits perfect to my problem!

Brar

Hi guys...

I want to create a simple TCP server which an ability to detect that client
is accidentally disconnected. I've tried using functions "sigaction",
"signal", "fcntl", "ioctl", etc including their constantas like :

fcntl(fd, F_SETFL, O_NONBLOCK | O_ASYNC);
fcntl(fd, 10 /* F_SETSIG */ );
fcntl(fd, F_SETOWN, (long) getpid());
ioctl(fd, 0x5452 /* FIOASYNC */);

BUT.................

Still cannot successfully detect remote disconnection......

I really get impressed by the power of Telnet client in RedHat 6.1. This
small program always detect when remote server was down or something like
that.  I dig the it's source code and put some fprintf() in function
"peerdied" but when the message "Connection closed by foreign host" appears,
my text has never been displayed.......How can that be???

Regards,
cinoban

When read() returns zero, the connection was closed on the other end.

This behavior is compatible with select(): it will just mark the
appropriate fd as available for reading, and you'll get the above
behavior when you try to read().

Quote:> I've tried using functions "sigaction", "signal", "fcntl", "ioctl",
> etc including their constantas like :

You only get SIGPIPE when you try to _write_ to a disconnected
socket.

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