test3.c

这个是学习嵌入式开发的重要例子

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#define BUFFER_SIZE	1024

int main(int argc, char **argv)
{
  // FILE *popen(const char *command, const char *mode);
  FILE *fp;

  //fp = popen("ls -l /tmp", "r");
  fp = popen("cat", "w");

  if (fp == NULL)
  {
    // Upon successful completion, popen() shall return a pointer to an open stream that can be used to read or write to the pipe. Otherwise, it shall return a null pointer and may set errno to indicate the error.
    fprintf(stderr, "popen() error: %s\n", strerror(errno));
    exit(1);
  }

  char buf[BUFFER_SIZE];

  //memset(buf, 0, BUFFER_SIZE);

#if 0
  //char *fgets(char *restrict s, int n, FILE *restrict stream);
  while (fgets(buf, BUFFER_SIZE, fp) != NULL)
  {
    fprintf(stdout, "%s", buf);
  }
#endif

  while (fgets(buf, BUFFER_SIZE, stdin) != NULL)
  {
    //fprintf(stdout, "%s", buf);
    //int fputs(const char *restrict s, FILE *restrict stream);
    fputs(buf, fp);
    fflush(fp);
  }

  fclose(fp);

  return 0;
}