Timestamp of Directory is Updated Whereas Files are Still Having Old Timestamps
 

Hi,


This may sound a very easy question but I am wondering as to why the timestamp of the directory is updated / current whereas the files inside it have not been updated or no new file has been created therein:

Maybe a file was deleted. Not sure if a directory gets it's timestamp updated when you access it. I think not actually. But clearly if you change the contents, it will change the directory timestamp. And one way to change contents is removal of a file. Therefore you would not see any file with the corresponding timestamp.

Also, not all filesystems actually update these timestamps. (In some cases, it's an option that you can configure.)

Although they are, in a sense, "convenient," the act of updating them means several additional round-trip disk-I/O operations, and they cause the physical areas on the disk which contain this information to be highly contended-for. The physical read/write head is forced to move-around much more than it otherwise could ... "and, for what?" Yeah, you might update something in it when you're having to read/write it for some other purpose, but otherwise it's just noise-traffic.

As rtmistler says, the ls command gives the time that the item listed was modified, so if it's a directory that could include deleting a file, moving one in, or moving one out — not just altering a file.

Access times are not given unless you ask with ls -lu but they are always recorded. You can use noatime and nodiratime as mount parameters in /etc/fstab to stop that, if you want to.