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I had Firefox running, then (possibly) as a result of a key combination I don't recall, it quickly vanished from screen and Task Bar/Window List.

ps ax | grep firefox returns the below+the unneeded grep firefox line (Both ps and the GUI Task Manager, show firefox with seemingly unchanging RSS, VM-SIZE and 0% CPU usage):

johndoe      1916 36.6 14.0 923772 504372 tty1    Sl   13:30  12:15 firefox

pstree | grep firefox returns:


How can I tell what state the program is in?

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up vote 1 down vote accepted

It's probably a zombie process.

Z defunct ("zombie") process, terminated but not reaped by its parent.

If you run ps ax | grep firefox it will show you the status of the process, you can check against this list of status of the process (you must read the STAT column). Sadly, is unlikely that without fiddling with debuggers you can recover your data.

tree probably doesn't show you the process for the same reason.

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Thanks Braiam - This is helpful (+1). From that list you referenced, it looks like it is in a interruptible sleep state. I have edited my question with the output of ps ax | grep firefox, hoping that you wouldn't mind elaborating on whether this means it can be recovered without use of debuggers (with a lot of time, I expect!). I see that other process' that are running fine also have a status of S*, so am hopeful that this is a good sign. Lastly, I assume reaped means cleaned up after? – user66001 Oct 19 '13 at 16:46
@user66001 you should ask that in another question, like "how to recover a process from interruptible sleep state". I think you will be more luck if you ask in Unix & Linux since there are pretty nasty Linux/Unix knowable people. – Braiam Oct 19 '13 at 17:18
Okay. Thanks. Historically though, I tend to get more answers/relevant info, on this sub site, than the generic Unix & Linux one, unfortunately. Lastly, I assume reaped means cleaned up after? – user66001 Oct 19 '13 at 17:27

Personally, I like top run from the command line. Works to find that pita app slowing everything down.

top in a terminal window

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Thanks for you answer, but how does this tell me if the program is frozen, running without a GUI window (If this is even possible in Linux), or (I believe is possible) detached from the GUI? – user66001 Oct 18 '13 at 2:52
If does tell you its PID so you can kill the process. Isn't that what you're going to have to do anyway? – Marc Oct 18 '13 at 3:01
If I wanted to kill the process, wouldn't have spent the time writing up the question, and could have used tools mentioned in my question to do so, without using top. There is important work unsaved (realise this is my fault), and if there is any chance that due to my limited Linux knowledge, I am missing something that indicates it is still running, but the window is detached (or something), I want to know. – user66001 Oct 18 '13 at 4:20

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