不明白这段话的意思？？

beginner2003

4.6 How to make a hacker-tools-directory unaccessible\r\n\r\nFor hackers it is often important to make the directory they use for their tools (advanced hackers don\'t use the regular local filesystem to store their data). Using the getdents approach helped us to hide directory/files. The open approach helped us to make our files unaccessible. But how to make our directory unaccessible ?\r\nWell - as always - take a look at include/sys/syscall.h; you should be able to figure out SYS_chdir as the systemcall we need (for people who don\'t believe it just strace the \'cd\' command...). This time I won\'t give you any source, because you just need to intercept sys_mkdir, and make a string comparison. After this you should make a regular call (if it is not our directory) or return ENOTDIR (standing for \'there exists no directory with that name\').\r\nFROM:http://blacksun.box.sk/lkm.html#II.4.6.\r\n\r\n请问一下，cd命令需要用到的是sys-chdir系统调用，为什么作者说截获sys-mkdir系统调用啊？？各位大虾，帮帮忙啊，谢谢。\r\n    \r\n

beginner2003

大家帮帮忙啊，要不然这个问题我永远都搞不清了。