linux实验一 一个简单的拷贝程序

/*本程序展示文件打开与读写的基本系统调用的使用*/#include<stdio.h>#include<fcntl.h>#define PERMS 0666#define DUMMY 0#define BUFSIZ 1024main(argc,argv)int argc;char *argv[];{int sfd,tfd,num;char iobuf[BUFSIZ];if(argc!=3){fputs("Usuage:cp Source Target",stderr);exit(1);}if((sfd=open(*(argv+1),O_RDONLY,DUMMY))==-1){fputs("Source file open fail",stderr);exit(2);}if((tfd=open(*(argv+2),O_WRONLY|O_CREAT,PERMS))==-1){fputs("Target file open fail",stderr);exit(3);}while((num=read(sfd,iobuf,BUFSIZ))>0)if(write(tfd,iobuf,num)!=num){fputs("Target file writed error",stderr);exit(4);}close(sfd);close(tfd);exit(0);}