Thread: provide input to another program

Is this linux or windows? Use a pipe. The second program can open a pipe to write to the first program.

a.out < inputfile
cat inputfile | a.out
Both do much the same.

Use popen(), defined in stdio.h. For example, for cross platform sockets :

Code:

#include <stdio.h>
#define BUFSIZE 100

int main(void) {
  char buf[BUFSIZE];

  FILE * f = popen("telnet example.com 80", "r+");
  if(f) {
    fprintf(f, "GET / HTTP/1.0\r\n\r\n");
    fread(buf, sizeof(char), BUFSIZE, f);
    buf[BUFSIZE-1] = '\0';

    printf("Result: '%s'\n", buf);

    pclose(f);
    return 0;
  }
  return -1;
}

The above will print the telnet header and the start of the response from example.com to a HTTP request. (Warning, it's untested, I'm behind a proxy at the moment.)

AFAIK: popen() can create bidirectional pipes on OS X and BSD, but only unidirectional on Linux and Solaris.

popen() is probably part of the POSIX standard, which is what Linux uses, but Windows generally uses the ANSI standard.

[edit]url[/edit]

[edit2]

This function is NOT included in 'C Programming Language' (ANSI) but can be found in 'The Standard C Library' book.

Taken from here.
[/edit2]

Originally Posted by dwks

popen() is probably part of the POSIX standard, which is what Linux uses, but Windows generally uses the ANSI standard.

There is no ANSI C standard method for opening pipes. Just like there's no standard method for reading a keystroke.


Quzah.

That's what my edit said.