CentOS中可以通過stat查看文件的元數據
[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：最后訪問時間
Modify：最后修改時間
Change：狀態更改時間(由系統維護，無法隨意修改)
touch -a ：僅更新Access time(同時更新Change為current time)
touch -m：僅更新Modify time(同時更新Change為current time)
touch -c：不創建新文件
touch -t：使用指定的時間更新時間戳(僅更改Access time與Modify time，Change time更新為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
當文件的任何數據改變時(包括文件的數據和元數據)，Change會更新，對文件重命名(mv)，移動(mv)或者復制時(cp -a)，系統都會更新文件的Change time。當文件的內容被修改時Modify和Change會同時更新。當Change time更新后，第一次訪問該文件，系統會更新Access time(僅更新Access time)，之后對該文件的訪問，將不會更新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更新時間戳后的第一次訪問，Access time更新了，下面是第二次訪問之后的元數據，Access time并沒有更新。
[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或者各種壓縮命令在解壓出來時都會更新文件的Change time，若想要不更改Change time備份文件可以使用dd命令(dd命令在復制單個文件時，會更新時間戳，在備份整個分區時，會保留文件的所有屬性)，過程如下：
新建一個分區sda10，不用格式化，掛載到/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掛載在/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
兩個文件的元數據一模一樣。
