cp.c

实现Shell

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <utime.h>

int
main(int argc, char **argv){
	struct stat s, s1;
	struct utimbuf times;
	int oldfile;
	int newfile;
	size_t nbytes=65534;
	ssize_t nbytes2;
	char buff[65535];
	if(stat(argv[1], &s)<0)  err_sys("stat error");
	oldfile=open(argv[1],O_RDONLY);
	if(oldfile<0)  err_sys("open file error");
	newfile=open(argv[2], O_RDWR | O_CREAT | O_TRUNC , s.st_mode);
	if(newfile<0)  err_sys("creat new file error");
	while(1){
		nbytes2=read(oldfile,buff,nbytes);
		if(nbytes2==0)	break;
		if(nbytes2<0)	err_sys("read file error");
		nbytes2=write(newfile,buff,nbytes2);
		if(nbytes2<=0)	err_sys("write file error");
	}
	close(oldfile);
	close(newfile);
	times.actime=s.st_atime;
	times.modtime=s.st_mtime;
	if(utime(argv[2],&times)<0)	err_sys("modify time error");
	return 0;
}