CentOS中可以通过stat查看文件的元数据
[baby@xiaoxiao abc]$ stat honey
File: `honey'
Size: 25 Blocks: 8 IO Block: 4096 regular file
Device: 806h/2054d Inode: 131076 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 500/ baby) Gid: ( 500/ baby)
Access: 2015-03-30 10:27:51.851234105 +0800
Modify: 2015-03-30 10:44:58.144226717 +0800
Change: 2015-03-30 10:44:58.146226803 +0800
Access：最后访问时间
Modify：最后修改时间
Change：状态更改时间(由系统维护，无法随意修改)
touch -a ：仅更新Access time(同时更新Change为current time)
touch -m：仅更新Modify time(同时更新Change为current time)
touch -c：不创建新文件
touch -t：使用指定的时间更新时间戳(仅更改Access time与Modify time，Change time更新为current time)
例：touch -t [[CC]YY]MMDDhhmm[.ss] filename
[root@xiaoxiao cde]# touch -t 199906121808 honey
[root@xiaoxiao cde]# stat honey
File: `honey'
Size: 25 Blocks: 8 IO Block: 4096 regular file
Device: 806h/2054d Inode: 131076 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 500/ baby) Gid: ( 500/ baby)
Access: 1999-06-12 18:08:00.000000000 +0800
Modify: 1999-06-12 18:08:00.000000000 +0800
Change: 2015-03-30 13:31:40.064221158 +0800
当文件的任何数据改变时(包括文件的数据和元数据)，Change会更新，对文件重命名(mv)，移动(mv)或者复制时(cp -a)，系统都会更新文件的Change time。当文件的内容被修改时Modify和Change会同时更新。当Change time更新后，第一次访问该文件，系统会更新Access time(仅更新Access time)，之后对该文件的访问，将不会更新Access time。
[baby@xiaoxiao cde]$ touch honey
[baby@xiaoxiao cde]$ stat honey
File: `honey'
Size: 25 Blocks: 8 IO Block: 4096 regular file
Device: 806h/2054d Inode: 131076 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 500/ baby) Gid: ( 500/ baby)
Access: 2015-03-30 11:24:47.041225726 +0800
Modify: 2015-03-30 11:24:47.041225726 +0800
Change: 2015-03-30 11:24:47.041225726 +0800
[baby@xiaoxiao cde]$ cat honey &> /dev/null
[baby@xiaoxiao cde]$ stat honey
File: `honey'
Size: 25 Blocks: 8 IO Block: 4096 regular file
Device: 806h/2054d Inode: 131076 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 500/ baby) Gid: ( 500/ baby)
Access: 2015-03-30 11:25:16.401228081 +0800
Modify: 2015-03-30 11:24:47.041225726 +0800
Change: 2015-03-30 11:24:47.041225726 +0800
用touch更新时间戳后的第一次访问，Access time更新了，下面是第二次访问之后的元数据，Access time并没有更新。
[baby@xiaoxiao cde]$ cat honey &> /dev/null
[baby@xiaoxiao cde]$ stat honey
File: `honey'
Size: 25 Blocks: 8 IO Block: 4096 regular file
Device: 806h/2054d Inode: 131076 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 500/ baby) Gid: ( 500/ baby)
Access: 2015-03-30 11:25:16.401228081 +0800
Modify: 2015-03-30 11:24:47.041225726 +0800
Change: 2015-03-30 11:24:47.041225726 +0800
tar或者各种压缩命令在解压出来时都会更新文件的Change time，若想要不更改Change time备份文件可以使用dd命令(dd命令在复制单个文件时，会更新时间戳，在备份整个分区时，会保留文件的所有属性)，过程如下：
新建一个分区sda10，不用格式化，挂载到/media/sda10。
[root@xiaoxiao cde]# ll /dev/sda10
brw-rw---- 1 root disk 8, 10 Mar 30 12:58 /dev/sda10
[root@xiaoxiao abc]# dd if=/dev/sda6 of=/dev/sda10 & (/dev/sda6挂载在/tmp下)
[1] 5917
[root@xiaoxiao abc]# mount /dev/sda10 /media/sda10/
[root@xiaoxiao cde]# stat /media/sda10/cde/honey /tmp/cde/honey
File: `/media/sda10/cde/honey'
Size: 25 Blocks: 8 IO Block: 4096 regular file
Device: 80ah/2058d Inode: 131076 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 500/ baby) Gid: ( 500/ baby)
Access: 2015-03-30 11:25:16.401228081 +0800
Modify: 2015-03-30 11:24:47.041225726 +0800
Change: 2015-03-30 11:24:47.041225726 +0800
File: `/tmp/cde/honey'
Size: 25 Blocks: 8 IO Block: 4096 regular file
Device: 806h/2054d Inode: 131076 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 500/ baby) Gid: ( 500/ baby)
Access: 2015-03-30 11:25:16.401228081 +0800
Modify: 2015-03-30 11:24:47.041225726 +0800
Change: 2015-03-30 11:24:47.041225726 +0800
两个文件的元数据一模一样。
