write.c

/*write.c*/
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define MAXSIZE

int main(void)
{
int i,fd,size,len;
char *buf="Hello! I'm writing to this file!";
char buf_r[10];
len = strlen(buf);
/*首先调用open函数，并指定相应的权限*/
if((fd = open("/tmp/hello.c", O_CREAT | O_TRUNC | O_RDWR,0666 ))<0){
perror("open:");
exit(1);
}
else
printf("open file:hello.c %d/n",fd);
/*调用write函数，将buf中的内容写入到打开的文件中*/
if((size = write( fd, buf, len)) < 0){
perror("write:");
exit(1);
}
else
printf("Write:%s/n",buf);
/*调用lsseek函数将文件指针移到文件起始，并读出文件中的10个字节*/
lseek( fd, 0, SEEK_SET );
if((size = read( fd, buf_r, 10))<0){
perror("read:");
exit(1);
}
else
printf("read form file:%s/n",buf_r);
if( close(fd) < 0 ){
perror("close:");
exit(1);
}
else
printf("Close hello.c/n");
exit(0);
}