I sometime have problem finding which persistent process is not letting me eject a volume (CD/DVD/USB drive). The error message is not very helpful at all:

Try quitting applications

OK, but which one(s)? I often have hard time figuring that out using htop/ top or a combination of ps and grep.

But actually this is what I want:

where Volume_Name is the name of the volume (or an ‘identifying’ part of the name) I want to eject. This gives me the name(s) and process ID(s) of the run-away process(es) as well as the path to the file(s) in use on the volume, Volume_Name.

Now that I know the names I should first try to save the documents and quit the applications involved in the normal way. However, if a particular application does not oblige, I can always kill it (with the risk of potential data loss!) using its process ID (say, 123):

After that, the ejection of the volume should not be difficult at all.

Needless to say, being a Unix utility, lsof (=“list open files”) may be used on other *nix-based systems as well.