APUE-3.2创建一个具有空洞的文件

创建文件Create_file_with_hole.c，内容为

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "apue.h"
char buf1[] = "abcdefghij";
char buf2[] = "ABCDEFGHIJ";
int
main(void) {
    int fd;
    if ( (fd = creat("file.hole", FILE_MODE)) < 0)
        err_sys("creat error");
    if (write(fd, buf1, 10) != 10)
        err_sys("buf1 write error");
    /* offset now = 10 */
    if (lseek(fd, 40, SEEK_SET) == -1)
        err_sys("lseek error");
    /* offset now = 40 */
    if (write(fd, buf2, 10) != 10)
        err_sys("buf2 write error");
    /* offset now = 50 */
    exit(0);
}

• 编译

gcc Create_file_with_hole.c -o Create_file_with_hole -lapue

• 执行

./Create_file_with_hole
//od命令用来观察该文件的实际内容，-c表示以字符方式打印文件内容
od -c file.hole

编译，执行结果为