更新20160912
來源man chattr
chattr [ -RVf ] [+-=[aAcCdDeijsStTu]] file
-R Recursively change attributes of directories and their contents.
-V Be verbose with chattr's output and print the program version.
-f Suppress most error messages.
屬性
a:檔案只能增加資料，不能覆蓋或刪除.
A:讀取檔案不會增加atime，減少disk存取次數.
c:the file is automatically compressed on the disk by the kernel.
C:the file will not be subject to copy-on-write updates.
d:the file is not candidate for backup.
D:the file changeling are written synchronously on the disk.
e:the file is using extents for mapping the blocks on disk.
E:the experimental encryption patches to indicate that the file has been encrypted.
The 'h' attribute indicates the file is storing its blocks in units of the filesystem blocksize instead of in units of sectors, and means that the file is (or at one time was) larger than 2TB.
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.
A file with the 'j' attribute has all of its data written to the ext3 or ext4 journal before being written to the file itself
A file with the 'N' attribute set indicates that the file has data stored inline, within the inode itself.
A directory with the 'P' attribute set will enforce a hierarchical structure for project id's.
When a file with the 's' attribute set is deleted, its blocks are zeroed and written back to the disk.
When a file with the 'S' attribute set is modified, the changes are written synchronously on the disk;
A file with the 't' attribute will not have a partial block fragment at the end of the file merged with other files (for those filesystems which support tail-merging).
A directory with the 'T' attribute will be deemed to be the top of directory hierarchies for the purposes of the Orlov block allocator.
When a file with the 'u' attribute set is deleted, its contents are saved.
The 'X' attribute is used by the experimental compression patches to indicate that the raw contents of a compressed file can be accessed directly.
The 'Z' attribute is used by the experimental compression patches to indicate a compressed file is dirty.
