Just downloaded the new Tor browser bundle on my MACBOOK Pro and I get a message that reads "a copy of firefox is already running. Only one copy allowed at a time." Any suggestions for newbie, like myself?

3 Answers 3


Although it is not a "true Linux way", you could also force kill Firefox processes through the
"System Monitor" application, which is a part of Mac OS X system


It sounds like you've opened the .dmg and are trying to run the program before copying it out.

Drag 'TorBrowser' on to your desktop (or a temp folder) and try to execute it again.


Verify, via the terminal command ps aux | grep firefox, that no previous Firefox process was abnormally stopped and kept in 'ghost' status.

If it's the case, kill the process via kill -9 <id> or reboot the machine and then verify again, via terminal command ps aux, that no Firefox process is still running.

  • Using SIGKILL seems a bit excessive. Maybe try SIGTERM first and use SIGKILL if that doesn't work?
    – user5
    Commented Jan 3, 2015 at 14:32
  • I've killed the process via the command posted and still no luck i keep reciving this message: bash: syntax error near unexpected token `11839' Kayras-MacBook-Air:~ MacBook$ killall firefox No matching processes belonging to you were found Kayras-MacBook-Air:~ MacBook$ what should i try next? does this mean i have a virus or my system is hacked? the firefox ID keeps changing with every command i enter.
    – user6815
    Commented Feb 26, 2015 at 2:42

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