创建一个文件，写进内容，拷贝新文件

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本文介绍了一个简单的C语言程序，该程序能够根据用户输入创建指定名称的文件，并将预定义的内容写入文件中。此外，程序还会自动创建该文件的一个备份副本，并命名为原文件名加.bak扩展名。

要求：写一个程序creat程序，其使用方法为：creat file_name "file content here" 该程序将创建一个文件名为第1个参数(file_name）的文件，并把第二个参数（"file content here"）作为文件内容，写入创建的文件中，然后再将该文件拷贝一份命名为file_name.bak;

实现：
	main.c
/*********************************************************************************
 *      Copyright:  (C) 2013 Yanshifu<Yanshifu@gmail.com>  
 *                  All rights reserved.
 *
 *       Filename:  apue_test_create.c
 *    Description:  This file 
 *                 
 *        Version:  1.0.0(09/10/2013~)
 *         Author:  Yan Shifu <Yanshifu@gmail.com>
 *      ChangeLog:  1, Release initial version on "09/10/2013 06:35:11 PM"
 *                 
 ********************************************************************************/
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>

#define  pstr       "file content here"

/********************************************************************************
 *  Description:
 *   Input Args:
 *  Output Args:
 * Return Value:
 ********************************************************************************/
int main (int argc, char **argv)
{
    int fd;

    if (argc < 2)
    {
        fprintf(stderr, "Usage :%s filename\n", argv[0]);
        exit(1);
    }

    createfile(argv[1], pstr, sizeof(pstr));

    copy(argv[1], ".bak");

    return 0;
} /* ----- End of main() ----- */

copy.c

/*********************************************************************************
 *      Copyright:  (C) 2013 Yanshifu<Yanshifu@gmail.com>  
 *                  All rights reserved.
 *
 *       Filename:  copy.c
 *    Description:  This file 
 *                 
 *        Version:  1.0.0(09/10/2013~)
 *         Author:  Yan Shifu <Yanshifu@gmail.com>
 *      ChangeLog:  1, Release initial version on "09/10/2013 09:52:07 PM"
 *                 
 ********************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>

#define bufsize     1046

void copy(char *filename, const char *cpyname)
{
    int     newsize, oldsize;
    int     ofd,nfd;
    char    name[bufsize];
    char    buf[bufsize];


    if ((ofd = open(filename, O_RDONLY)) < 0)
    {
        printf("open file error in copy\n");
        exit(1);
    }

    if ((oldsize = read(ofd, buf, bufsize)) < 0)
    {
        printf("read oldfile error\n");
        exit(2);
    }

    strcpy(name, filename);
    strcat(name, cpyname);

    if ((nfd = creat(name, 0666)) < 0)
    {
        printf("create newfile error\n");
        exit(3);
    }


    if ((newsize = write(nfd, buf, oldsize)) < 0)
    {
        printf("write newfile error");
        exit(4);
    }

    close(ofd);
    close(nfd);

creat.c

/*********************************************************************************
 *      Copyright:  (C) 2013 Yanshifu<Yanshifu@gmail.com>  
 *                  All rights reserved.
 *
 *       Filename:  create_file.c
 *    Description:  This file 
 *                 
 *        Version:  1.0.0(09/10/2013~)
 *         Author:  Yan Shifu <Yanshifu@gmail.com>
 *      ChangeLog:  1, Release initial version on "09/10/2013 06:37:11 PM"
 *                 
 ********************************************************************************/
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>

void createfile(const char *filename, const char *str, int len)
{
    int fd, size;

    if ((fd = creat(filename, 0666)) < 0)
    {
        printf("open error\n");
        exit(1);
    }

    if ((size = write(fd, str, len)) < 0)
    {
        printf("write error\n");
        exit(2);
    }

    close(fd);

}

copy.h

/********************************************************************************
 *      Copyright:  (C) 2013 Yanshifu<Yanshifu@gmail.com>
 *                  All rights reserved.
 *
 *       Filename:  fun.h
 *    Description:  This head file 
 *
 *        Version:  1.0.0(09/10/2013~)
 *         Author:  Yan Shifu <Yanshifu@gmail.com>
 *      ChangeLog:  1, Release initial version on "09/10/2013 09:02:44 PM"
 *                 
 ********************************************************************************/

#ifndef _COPY_H
#define _COPY_H

void    copy(char *filename, const char *cpyname);


#endif
~

creat.h

/********************************************************************************
 *      Copyright:  (C) 2013 Yanshifu<Yanshifu@gmail.com>
 *                  All rights reserved.
 *
 *       Filename:  create.h
 *    Description:  This head file 
 *
 *        Version:  1.0.0(09/11/2013~)
 *         Author:  Yan Shifu <Yanshifu@gmail.com>
 *      ChangeLog:  1, Release initial version on "09/11/2013 10:18:01 AM"
 *                 
 ********************************************************************************/

#ifndef _CREATE_H
#define _CREATE_H


void  createfile(const char *filename, const char *str, int len);

#endif

makefile

bins=main
objs=main.o
srcs=main.c
$(bins):$(objs)
        gcc -o main main.o copy.o create.o

$(objs):$(srcs)
        gcc -c main.c

        gcc -c copy.c copy.h

        gcc -c create.c create.h

clean:
        rm -f $(bins) *.o *.h.gch