郁闷阿

C/C++ code

#include "apue.h"
#include <fcntl.h>
#include <sys/mman.h>
int main(int argc,char **argv)
{
        int fdin,fdout;
        void *src,*dst;
        struct stat statbuf;
        
        if(argc!=3) err_quit("usge: %s <fromfile> <tofile>",argv[0]);
        if((fdin=open(argv[1],O_RDONLY))<0)
                err_sys("can not open %s for reading",argv[1]);
        if((fdout=open(argv[2],O_RDWR | O_CREAT | O_TRUNC,FILE_MODE))<0)
                err_sys("can not create %s for wrtting",argv[2]);
        if(fstat(fdin,&statbuf)<0) err_sys("fstat error");
        if(lseek(fdout,statbuf.st_size-1,SEEK_SET)==-1)
                err_sys("lseek error");
        if(write(fdout," ",1)!=1) err_sys("write error");
        if((src=mmap(0,statbuf.st_size,PROT_READ,MAP_SHARED,fdout,0))==MAP_FAILED)
                err_sys("mmap error for output");
        if((dst=mmap(0,statbuf.st_size,PROT_READ | PROT_WRITE,MAP_SHARED,fdout,0))==MAP_FAILED)
                err_sys("mmap error for output");
        memcpy(dst,src,statbuf.st_size);
        msync(src,statbuf.st_size,MS_SYNC);
        exit(0);
}

编译Steven大神的代码，后
root@suma:/home/suma/桌面# cc test.c
root@suma:/home/suma/桌面# ./a.out test.c mm.c
root@suma:/home/suma/桌面# od -c mm.c
0000000 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0
*
0002100 \0 \0 \0 \0 \0 \0 \n
0002110
用gedit也没法看，大家给个情况，谢谢

对了系统是ubuntu,test.c就是源文件

./a.out 不能运行吗?