Why can non-empty directories not be deleted directly? [self-answered]

[This is a self-answered question. Just added for completeness.]

Deletion works by unlinking a file from the file system tree and marking the space it occupied as unused. If a directory was unlinked from the file system without deleting its contents first, the space occupied by those files would not be made free, so it would waste space.

This is why a non-empty directory can't just be deleted in a single operation.

Originally Posted by exerceo [This is a self-answered question. Just added for completeness.] Deletion works by unlinking a file from the file system tree and marking the space it occupied as unused. If a directory was unlinked from the file system without deleting its contents first, the space occupied by those files would not be made free, so it would waste space. This is why a non-empty directory can't just be deleted in a single operation.

While as far as I know you're correct; I don't think this is the right place to be posting questions that you've already answered. I think this should be posted maybe in your blog or maybe the "Linux Tutorials" forum instead of here.

Originally Posted by why_bother While as far as I know you're correct; I don't think this is the right place to be posting questions that you've already answered. I think this should be posted maybe in your blog or maybe the "Linux Tutorials" forum instead of here.

Blogs are not indexed by search engines because they can only be seen while logged in. And it is not exactly a tutorial either. It is a technical explanation for a behaviour.

what do you mean by "a single operation"? rm -rf <dir> will delete that dir (regardless of its content, as long as you are allowed to remove all or them).

Originally Posted by exerceo Blogs are not indexed by search engines because they can only be seen while logged in. ...

You can set the relevant blog setting to make your blog visible to people who aren't logged in. Yes, as some do, you can also set it so it's not visible to those not logged in too.

Originally Posted by exerceo Blogs are not indexed by search engines because they can only be seen while logged in.

Even if that were true (it isn't; just enable the "Guests may... View your blog" option in Blog Settings), one one can create a blog on many different platforms.

However...

Originally Posted by exerceo Just added for completeness.

Your explanation is far from complete.

If this were a blog entry, I would expect a much more comprehensive answer to this question.

Also...

Why can non-empty directories not be deleted directly?

They can, "rm -r dir" will delete a directory that contains files. (Blindly using -rf options is a stupid habit.)

As the -v option will show, it simply removes the files in each directory first.

One way to do it, IIRC, is rm -rf dirname. This will delete everything in the directory and then the directory entry itself.

The only function of rmdir is to delete empty directories mainly as a safety feature AFAIK. Otherwise as posted rm can delete non empty directories in a single operation but it requires the use of options.

Originally Posted by pan64 what do you mean by "a single operation"? rm -rf <dir> will delete that dir (regardless of its content, as long as you are allowed to remove all or them).

Originally Posted by boughtonp They can, "rm -r dir" will delete a directory that contains files. (Blindly using -rf options is a stupid habit.)

Originally Posted by sundialsvcs One way to do it, IIRC, is rm -rf dirname. This will delete everything in the directory and then the directory entry itself.

Indeed, but that command performs many operations. Each file requires one deletion operation. If a folder contains 50000 files, it requires this many file operations to delete the folder.

I have read in some comment (I can't remember where) that someone believes rmdir's inability to delete non-empty directories is just for safety. But that is only half the truth.

Huh ... I don't think I've ever actually used "rmdir."