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Scenario (Ubuntu 14.04.2) :
I wake Ubuntu from suspend.
I know (from past experience) that it only takes 2 or 3 seconds for the lock screen to become available.
My monitor, however, takes longer - maybe 3 - 5 seconds.
So usually I will start typing my password at the lock screen before my monitor's ready. (I hold off pressing "Enter" until I can see the lock screen though, just in case).
90% of the time, this works fine.

However ... on rare occasions, when my monitor comes on, I see an error message at the command line. Something like "... kernel: [68165.146584] ata5: COMRESET failed (errno=-16)" for example.
Then in another second or two when the lock screen appears, the password field is empty.

My question is :
Where does my partially-typed password go, when I unknowingly type it at an error message on the command line ?
... Would someone with physical access to my computer be able to switch to a particular VTY/TTY and see my partial password ?
Or, say, kill X and see it sitting - in plain text - at a shell prompt indefinitely somewhere ?

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When you type keys are stored in a buffer, when that buffer is filled you will start listening bips whenever you type extra caracters, those characters are discarded (if my memory serves me well).

The next thing depends on what the first program that access that buffer do. If it first discards the buffer content a start reading your keystrokes will be lost, if it reads that buffer then your keystrokes are recovered, as if you lauch a command in the command line and takes some time, you can type something and it will be displayed later.

Regarding if someone can see what you are typing... if he has access to the buffer before it is read or erased then yes, someone can read what you typed.

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    Ah, I'm not concerned about my password being stored in memory (in a buffer, as you say). Rather, I am concerned that when I type my password NOT at the password prompt of the lock screen, that each individual character of my password is printed to the console somewhere where I couldn't normally see it once X has started back up soon after wake-up. Does that help clarify what I mean to ask ? Commented Mar 16, 2015 at 16:57
  • YoMismo: This is a half-decent answer to the question’s title, but not a very good answer to the question. “The next thing depends on … the first program that access[es] [the keystroke] buffer …” OK, when the computer is waking from suspend, what process other than the lock screen has access to the keyboard input buffer? … (Cont’d) Commented Mar 16, 2015 at 19:49
  • (Cont’d) … And your statement, “if [someone] has access to the buffer before it is read or erased then yes, [he] can read what you typed.” is a non-answer. It’s as if I asked, “Can anybody see what I do in my windowless basement from outside my house?” and you answered, “If someone can see through bricks, rocks, and stones, then, yes, he can see into your basement.” This is what’s known as begging the question. Commented Mar 16, 2015 at 19:50
  • @scott or has set a tv cammera in your basement with outside communication. Yes, someone can see what you do in your basement. If you are completly sure no one has entered your basement and set a cammera, then rethink and don't be so sure. Commented Mar 17, 2015 at 7:11
  • @YoMismo: Exactly! That would be a reasonable answer to the question “Can anybody see what I do in my windowless basement from outside my house?” But, “If someone can see through bricks, rocks, and stones, then, yes, he can see into your basement” is not a useful answer, because it just leads to the question, “Can anybody can see through bricks, rocks, and stones?” And, in just the same way, “if [someone] has access to the buffer before it is read or erased then yes, [he] can read what you typed” is useless because it’s hypothetical; it doesn’t say whether any actual person has that ability. Commented Mar 17, 2015 at 7:24

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