I use KeepassX to store passwords for personal passwords, and for work. On recent OS X installs KeePassX dropped support for the version 1 file format. But on my linux desktops there is no new KeePassX that supports the version 2 file format.
Fortunately someone packaged KeePass2 for Debian, a .NET app that runs under Mono. Unfortunately there is a problem with copying the password from KeePass2 into applications. http://ubuntuforums.org/showthread.php?t=1891919 is another user having the problem. http://www.sparrowtail.com/linux-and-its-schizophrenic-clipboards is where someone worked out what was going on, an explained it. http://www.nongnu.org/autocutsel/ is some software that provides the solution.
It seems in an X-Window system there is an old and deprecated cutbuffer, where applications can store text. Then there is a modern scheme called 'selections'. Supposedly applications these days use a 'PRIMARY' or a 'CLIPBOARD' selection, and perhaps the mono app uses the cutbuffer. the autocutsel tracks the cutbuffer and a selection (defaulting to CLIPBOARD) and copies text between them.
But that explanation from sparrowtail.com is from 2010, and autocutsel doesn't sort this out for me. The autocutsel package includes a "cutsel" tool that shows you what is in the cutbuffer and the selections. My testing shows that if I highlight something in a gnome terminal, it does show up in the PRIMARY selection. If I do a Shift+Ctrl+C copy it does show up in the CLIPBOARD selection. In KeePass2 if I do a copy it also shows up in the CLIPBOARD selection, (until a timer, and then KeePass2 removes the selection, and 'cutsel' reports Nobody owns the selection.
And while the copied password is in the CLIPBOARD selection (owned by KeePass2) I can past it in GVIM. But I still can't paste it into a terminal.
After reading https://en.wikipedia.org/wiki/X_Window_selection, I suspect an active selection process is occurring, and for some reason KeePass2 is refusing the paste when the other application is a terminal. Continuing to read that suggested I might be able to run xclipboard (to take over the selection). But I'm told another clipboard is already running when I launch it. https://lildude.co.uk/howto-use-xclipboard-with-gnome/ suggests gnome includes it's own clipboard manager now. So I installed glipper, which describes itself as a "Clipboard manager for GNOME". Given that gnome is already a clipboard manager, I'm assuming this will expose some GUI controls so I can interact with the clipboard.
And it kind of does. It keeps a copy of your clipboard. I still can't paste to gnome terminal when KeePass2 has control of the selection, but I can click on the glipper icon in the notification area to select the password from the history list, and then I can paste it.
So now I've got sensitive passwords being kept in a history, but I can paste them where I need to. This seems to have been a very unhealthy dose of yak shaving.