Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I would like to open a new instance of Firefox. I tried

firefox -no-remote


MOZ_NO_REMOTE=1 firefox

as detailed in the docs. However I keep getting the message

Firefox is already running, but is not responding. To open a new window, 
you must first close the existing Firefox process, or restart your system.

How can I launch a new instance of Firefox from command line?

share|improve this question
You can use something like firefox -url or just firefox to open a new instance of the browser in a new window. – martineau Feb 16 '13 at 20:26
@martineau I dont think you understand "new instance". That is 2 processes of firefox. – Steven Penny Feb 16 '13 at 20:30
up vote 8 down vote accepted

The -no-remote option is used for running multiple Firefox profiles at the same time. You are getting the "Firefox is already running" message because you are trying to open a second Firefox instance with the same profile.

You should be using this option as follows:

firefox -no-remote -P "Another Profile"


firefox -no-remote -profile "profile_path"

where profile_path is an absolute or relative (to firefox.exe) path.

share|improve this answer

I had the same need like you : running many instances of firefox on the same machine.

Basically, when you run an instance of firefox, there is a folder .mozilla in your $HOME is created ( if it is not existed yet). You can use the multi-profile solution if you want, as iglvzx mentioned above. So all user's profiles live in that .mozilla directory(database).

I have another trick which I think is more elegant than that solution. Create a directory to save a new firefox:

$ mkdir $HOME/new_firefox

$ cd $HOME/new_firefox

$ tar xvf setup/firefox-33.0.tar.bz2

Then create a small script like:

$HOME/firefox/firefox -no-remote &

So now run the scrip to have another instance of firefox. And your new user's profile live in $HOME/new_firefox/.mozilla.

If you use GNOME, just create a new_firefox.desktop file and put it in /usr/share/applications directory or in $HOME/.local/share/applications directory. The Exec argument in that file is Exec=/home/your_name/path-to-your-script. If you don't know how to create one, see an existed one in either of 2 above directory.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.