"The operation can't be completed because the item X is in use."

[fregante]

"The operation can't be completed because the item X is in use."

[sindresorhus]

What OS? Why should it do that?

[fregante]

Sorry, I mean OS X 10.11

It could do that because it's a command to empty the trash but it doesn't actually empty the trash since files in use can't be removed. It does follow the OS' native behavior, but that doesn't really do what I'm telling it to do: the trash won't be empty.

[sindresorhus]

macOS used have a trick to work around that. If you used "Empty trash securely" it would empty it regardless of "files in use". That option went away in El Capitan. I don't think there's any good way to do this now other than rm -rf, but I don't want to do that.