copy_system.c

this program can copy source file to destination file

#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>

int main()
{
//char c;
char block[1024];
int nread;
int in, out;

in = open("str.cpp",O_RDONLY);
out = open("str.bak",O_WRONLY|O_CREAT, S_IRUSR|S_IWUSR);
printf("in is %d,out is %d\n",in,out);
while((nread=read(in,block,sizeof(block)))>0)
	write(out,block,nread);

exit(0);
}