p2-5.c

SUN Solaris8平台下进程间通信

#include <stdio.h>
#include "err_exit.h"
int main (int argc, char *argv[])
{
    int n;
    FILE *from, *to;
    char buf[BUFSIZ] ;
    /*检查参数。*/
    if (argc != 3) {
       fprintf(stderr, "Usage : %s from-file to-file\n", *argv) ;
       exit (1);
    }
     /*为读而打开from-file文件*/
    if ((from = fopen(argv[1],"r")) == NULL) 
        err_exit (argv[1] ) ; 
    /*以添加方式打开文件to-file. 若此文件不存在，fopen 将创建它。*/
    if ((to = fopen(argv[2], "a")) == NULL)
        err_exit(argv[2] ) ;
     /*现在每次可以从文件from-file读入并写至to-file. 注意我们写出的字符个数是实际读入
       的字符个数而不总是BUFSIZ字节。*/
    while ((n = fread(buf, sizeof(char),BUFSIZ,from)) > 0)
        fwrite (buf, sizeof(char),n,to) ;
     /*关闭文件*/
    fclose (from) ;
    fclose (to) ;
    exit (0) ;
}