Linux – Unix/Linux find and sort by date modified

You can cancel/undo the sort by sender and return to the default sort by clicking on the Who header again. This partially solves your problem as it returns the sort to the default sort order.

You can then use CTRL+HOME to move the cursor to the top - and use TAB to move to the next unread.

Many questions, so I'm going to answer the "how does it work" part, not "how do I get this working."

This is dependent on the file system used. I'm answering based on ext[234], others probably work the same way or similarly.

1. No, the directory modification time doesn't change if a file is modified. The directory is not modified in this case in any way, it still contains the same files, directories etc linked to it.

2. The same as previous, if "changing a file" means the same as "modifying some file."

   If you remove a file and add a new one with the same name, or move another file "on top" of another, then the directory is modified.

3. When the directory is modified. This means linking/unlinking inodes into it, like files or subdirectories.

   Permission changes alter the change time, but not modification time. These are different.

   If you move the directory elsewhere, the change time will change, but modification time won't.

4. Directory access time is changed when the directory is accessed, if it hasn't been turned off. The volume might be mounted with noatime which means no last access time is written usually. Note that directory data is also cached.

   Also if you just access a subdirectory, the access time on the parent(s) doesn't change.

So if you search for directories not changed in the past 300 days, they might still contain files that have changed. File creation or removal hasn't happened, but editing contents may have. You will have to check by files as you said.