文件特殊权限：SUID,SGID,SBIT

[root@zhangshibo temp]# touch test
[root@zhangshibo temp]# chmod 4755 test;
[root@zhangshibo temp]# ls -l test
-rwsr-xr-x 1 root root 0 Oct 22 09:42 test
[root@zhangshibo temp]# chmod 6755 test;ls -l test
-rwsr-sr-x 1 root root 0 Oct 22 09:42 test
[root@zhangshibo temp]# chmod 1755 test;ls -l test
-rwxr-xr-t 1 root root 0 Oct 22 09:42 test
[root@zhangshibo temp]# chmod 7666 test;ls -l test
-rwSrwSrwT 1 root root 0 Oct 22 09:42 test
[root@zhangshibo temp]# chmod u=rwxs,go=x test;ls -l test
-rws--x--x 1 root root 0 Oct 22 09:42 test
[root@zhangshibo temp]# chmod g+s,o+t test;ls -l test
-rws--s--t 1 root root 0 Oct 22 09:42 test
[root@zhangshibo temp]#