dup2简单应用

/* ************************************************************************
 *       Filename:  dup_example.c
 *    Description:  
 *        Version:  1.0
 *        Created:  2011年04月14日 20时13分10秒
 *       Revision:  none
 *       Compiler:  gcc
 *         Author:  wenhao (wh), [e-mail]
 *        Company:  sunplusapp
 * ************************************************************************/

#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdlib.h>
#define BUFFER_SIZE 1024

int main(int argc, char *argv[])
{
  int fd;
  char buffer[BUFFER_SIZE];
  
  if(argc != 2)
  {
    fprintf(stderr,"Usage:%s utfilename/n/a",argv[0]);
    exit(EXIT_FAILURE);
  }

  if((fd=open(argv[1],O_WRONLY|O_CREAT|O_TRUNC,S_IRUSR|S_IWUSR)) == -1)
  {
    fprintf(stderr,"Open %s Error:%s/n/a",argv[1],strerror(errno));
    exit(EXIT_FAILURE);
  }
  if(dup2(fd,fileno(stdout)) == -1)
  {
    fprintf(stderr,"Redirect standard out error:%s/n/a",strerror(errno));
    exit(EXIT_FAILURE);
  }
  fprintf(stderr,"Now,please input string");
  fprintf(stderr,"(to quit use CTRL+D)/n");
  while(1)
  {
    fgets(buffer,BUFFER_SIZE,stdin);
    if(feof(stdin))
      break;
    write(fileno(stdout),buffer,strlen(buffer));
  }
  exit(EXIT_SUCCESS);
//  return 0;
}