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I have two instances of firefox running under separate profiles:

$ firefox -P default &
$ firefox -no-remote -P second &

Now I can open a new tab from the command line with:

$ firefox -new-tab http://unix.stackexchange.com

But how do I open a new tab in the second profile?


$ firefox -P second -new-tab http://unix.stackexchange.com

opens a tab in the default profile, while:

$ firefox -no-remote -P second -new-tab http://unix.stackexchange.com

complains that there is already an instance running under that profile.

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You need to use -new-instance instead of -no-remote (see bug #716110). But even that doesn't work as of Firefox 29: firefox -P second URL still contacts the first instance. – Gilles May 10 '14 at 11:47

It works now with firefox 29.0 on Linux:

To open a second firefox instance with a different profile:

firefox -P second -new-instance

To open a new tab in the second instance of firefox, which os already running:

firefox -P second -remote "openurl(http://example.com,new-tab)"

See Bug 716110 - split -new-instance flag out of existing -no-remote flag for additional hints (eg: post of Hayo).

As explained in the comments on this bug report, what is missing is a command that can be used for opening the first window and the second tab in the same way:

That could be done with a script along the lines of this (firefox-profile-instance):



if firefox -P "$PROFILE" -remote "ping()" >/dev/null 2>&1 ; then
    firefox -P "$PROFILE" -remote "openurl($URL,new-tab)"
    firefox -P "$PROFILE" -new-instance "$URL" &

Now, while a firefox with the default profile is already running,
the first run of this starts a new browser with profile "second":

firefox-profile-instance second "http://example.com"

and running the same again opens a second tab in the same browser:

firefox-profile-instance second "http://example.com"

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