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I have Firefox 3.6 installed on my OS X (10.6) box. I would like to open an URL in the running Firefox instance (in a new tab or window, no matter) from the command line. I tried several ways, neither switches -new-tab, -new-window, -url, or none helped me. I always get the A copy of Firefox is already open. Only one copy of Firefox can be open at a time. error message.

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The exact same thing is happening for me with the same setup. – Toby Feb 26 '10 at 16:32
up vote 6 down vote accepted



from the command line will (at least for me) open a new tab to in firefox (which is my default browser)

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open -a FireFox if you have a different default browser – cobbal Feb 26 '10 at 17:16
@cobbal, though it will work whatever case you use, Firefox really just needs one uppercase F... :-) – Arjan Feb 27 '10 at 10:22
Indeed, I think I've been using too much Objective-C, where everything is camelCased – cobbal Feb 28 '10 at 1:54
It works, thanks. – Török Gábor Mar 1 '10 at 14:50
@cobbal, bad ExCuse, not EveryThing is CamelCased. ;-) – Arjan Mar 2 '10 at 8:24

Sounds like a bug in FireFox, since the mozilla website clearly states that for opening a website (from command line) under OS-X should be:

firefox -url

The -url can be omitted, and the -new-tab switch added to force a new tab.

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I just tried it under windows and "firefox.exe" opens google in a new tab, in a running browser. – Roald van Doorn Feb 26 '10 at 20:17
Yes, I know it should work the way you mentioned, but it doesn't for some reason. – Török Gábor Mar 1 '10 at 14:49

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