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atime: access time \r\n\r\n mtime: modify time (timestamp)\r\n\r\n ctime: change time \r\n\r\n \r\n\r\n mtime 和ctime 的区别在于是更改文件内容,还是更改文件属性。前者是文件内容发生了变化,后者是文件的索引节点发生变化。\r\n\r\n 如,touch 文件abc.123,看atime, mtime, ctime\r\n\r\n #istat abc.123\r\n\r\nInode 1271 on device 10/4 File\r\n\r\nProtection: rw-r--r--\r\n\r\nOwner: 0(root) Group: 0(system)\r\n\r\nLink count: 1 Length 0 bytes\r\n\r\n \r\n\r\nLast updated: Mon Jan 02 16:24:44 2006 (ctime)\r\n\r\nLast modified: Mon Jan 02 16:24:44 2006 (mtime) \r\n\r\nLast accessed: Mon Jan 02 16:24:53 2006 (atime)\r\n\r\n \r\n\r\n# chmod a+x abc.123 \r\n\r\n修改文件属性,再看atime, mtime, ctime)。\r\n\r\n \r\n\r\n# istat abc.123\r\n\r\nInode 1271 on device 10/4 File\r\n\r\nProtection: rwxr-xr-x\r\n\r\nOwner: 0(root) Group: 0(system)\r\n\r\nLink count: 1 Length 0 bytes\r\n\r\n \r\n\r\nLast updated: Mon Jan 02 16:39:30 2006 \r\n\r\nLast modified: Mon Jan 02 16:24:44 2006\r\n\r\nLast accessed: Mon Jan 02 16:24:53 2006\r\n\r\n 其中ctime发生了变化。\r\n\r\n \r\n\r\n 最后修改文件内容\r\n\r\n # echo foo >> abc.123\r\n\r\nInode 1271 on device 10/4 File\r\n\r\nProtection: rwxr-xr-x\r\n\r\nOwner: 0(root) Group: 0(system)\r\n\r\nLink count: 1 Length 4 bytes\r\n\r\n \r\n\r\nLast updated: Mon Jan 02 16:48:51 2006\r\n\r\nLast modified: Mon Jan 02 16:48:51 2006\r\n\r\nLast accessed: Mon Jan 02 16:24:53 2006\r\n\r\n 其中mtime, ctime都发生了变化,mtime被更新很容易理解,ctime 被更新也一样可以理解,因为文件内容被修改时,索引节点的length字段也随之变化。\r\n\r\n \r\n\r\n atime: 访问时间是文件最后一次被读取的时间。因此阅读一个文件会更新它的访问时间,如:\r\n\r\n# cat abc.123\r\n\r\nfoo\r\n\r\n# istat abc.123\r\n\r\nInode 1271 on device 10/4 File\r\n\r\nProtection: rwxr-xr-x\r\n\r\nOwner: 0(root) Group: 0(system)\r\n\r\nLink count: 1 Length 4 bytes\r\n\r\n \r\n\r\nLast updated: Mon Jan 02 16:48:51 2006\r\n\r\nLast modified: Mon Jan 02 16:48:51 2006\r\n\r\nLast accessed: Mon Jan 02 16:55:14 2006 |
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