[lloeki]

Might be. Some terminal emulators save logs. "Unlimited scrolling" often goes to disk, possibly in a file, possibly in swap (Terminal.app makes it stay in memory, which once consumed 3GB of RAM for my long-lived "rails server" tab). iTerm2 allows you to navigate back in time, while Terminal.app saves some data on quit to display on restore (if OSX autosave is enabled).

[jaseg]

When you allow less common tools to be used, one could use the bash or zsh read-builtin to read the master password without echoing (e.g. dash's read can not do that) and use xclip or similar to directly put the password into the X clipboard. With xclip's -l option you could even automagically "forget" the clipboard after it was pasted once.