From:	Jorge Pacios =?iso-8859-1?Q?Mart=EDnez?= <jpacios AT gmv DOT es>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Tcl/Tk and C interaction problem
Date:	Thu, 18 Mar 1999 17:26:12 +0100
Organization:	GMV
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	I have compiled the following dummy program with DJGPP gcc:

-----------------------------------------------------------------------
# include <stdio.h>
# include <string.h>

void readcommand (char *str) {
  char ch;
  int i = 0;

  read(0, &ch, 1);
  while (ch!='\n') {
    str[i] = ch;
    i++;
    read(0, &ch, 1);
  }
  str[i] = '\0';
}

void main (void) {
  char prompt [] = "\necho> ";
  char cmd [1000];
  printf("%s", prompt);
  fflush(stdout);
  readcommand(cmd);
  while (strcmp(cmd, "quit") != 0) {
    printf("%s", cmd);
    printf("%s", prompt);
    fflush(stdout);
    readcommand(cmd);
  }
}
-----------------------------------------------------------------------

	As everybody can see, it just reads input and echoes it,
displaying a prompt.

	I am willing to make a Tcl/Tk interface to this program,
sending strings to it and reading its output (I open the program with
a pipe). The problem is, I always get blocked when trying to read from
the pipe.
	...I have compiled the *same* program with the gcc program
provided by gnat-3.09-nt --a cygwin.dll based compiler, I think-- and
the interface works perfectly.

	Maybe a buffering problem?

	Thanks,

		J. Pacios

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