推出移動硬盤失敗，解決方案：
- 執行
lsof /Volumes/Seagate/可以看到哪些進程在占用磁盤
$ lsof /Volumes/Seagate/
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
QuickLook 1281 hangj 7r REG 1,11 806150 396515 /Volumes/Seagate/a/b/c.docx
- 打開活動監視器 Activity Monitor，找到 QuickLook，強制退出，或者執行下面的命令
$ lsof /Volumes/Seagate/ | grep -v PID | awk '{ print $2 }' | xargs kill -9
如果 lsof /Volumes/Seagate/ 沒有輸出的話，加上 sudo 再執行 sudo lsof /Volumes/Seagate/，估計會發現是 mds 和 mds_store 在后台搞鬼, 這兩個是 SpotLight 的進程，強退之！
參考鏈接：
https://mycyberuniverse.com/macos/how-fix-volume-cant-be-ejected-because-currently-use-user.html
https://serverfault.com/questions/159422/os-x-determine-which-application-is-accessing-a-hdd-and-preventing-ejection
After some investigation I found that in my case this is the QuickLook process. The QuickLook process is a feature that was introduced in the Mac OS X 10.5 Leopard. You can learn more about it here. I noticed that when I use the Quicklook feature to preview a video in any format, the process keeps active even when the Quicklook window was already closed. If I preview any other file like PDF or JPG the disk can be ejected normally. Why does Quicklook preventing me from ejecting my disk? I suspect that this is just a bug.
還是不行的話，就退出登錄，然后再登錄進來。
還是不行的話，重啟電腦吧