在家/home打了顯示檔案隱藏屬性lsattr, 居然發現了大寫的I(通常是小寫的i，有這個參數)
請問這是什麼意思如下?

root@ubuntu-1204LTS:/# lsattr /home
-------------e- /home/apayuser
-------------e- /home/impuser
-------------e- /home/radio893memo
-------------e- /home/radioadvertisement
-------------e- /home/movie
-------------e- /home/fei
-------------e- /home/radioguestprogram
-------------e- /home/radiocommodity
-------------e- /home/radioengineer
-------------e- /home/engineer
-------------e- /home/ttdttd123
-------------e- /home/hard
----i--------e- /home/lin
----------I--e- /home/goothby
-------------e- /home/yuchun

查詢 manual

* man lsattr
* man chattr

可以看到

The letters `acdeijstuACDST' select the new attributes for the files:
append only (a), compressed (c), no dump (d), extent format (e),
immutable (i), data journalling (j), secure deletion (s), no tail-
merging (t), undeletable (u), no atime updates (A), no copy on write
(C), synchronous directory updates (D), synchronous updates (S), and
top of directory hierarchy (T).

The following attributes are read-only, and may be listed by lsattr(1)
but not modified by chattr: huge file (h), compression error (E),
indexed directory (I), compression raw access (X), and compressed dirty
file (Z).

The 'I' attribute is used by the htree code to indicate that a
directory is being indexed using hashed trees. It may not be set or
reset using chattr(1), although it can be displayed by lsattr(1).

A file with the `i' attribute cannot be modified: it cannot be deleted
or renamed, no link can be created to this file and no data can be
written to the file. Only the superuser or a process possessing the
CAP_LINUX_IMMUTABLE capability can set or clear this attribute.