Maybe you can achieve this with the Private Tab extension (pref: allowOpenExternalLinksInPrivateTabs) or ask to add this feature.

• Private Tab: https://addons.mozilla.org/firefox/addon/private-tab/

• http://forums.mozillazine.org/viewtopic.php?f=48&t=2665169

@cor-el so how am i going to open private tab via command line and navigate url ?

1. Go to the Firefox menu.
2. Go to open private window

Another window will pop up on firefox, and then you can use private browsing.

I'm not sure if you can do this via the command line.

• Bug 829180 - Externally opened urls may open in private browsing windows

(Please DO NOT comment in bug reports: https://bugzilla.mozilla.org/page.cgi?id=etiquette.html)

You should be able to drag a link in a Private Browsing mode window or a private tab.
Note that the Private Tab extension has a check-box in the right-click context menu of the tab on the tab bar to toggle the private mode of a tab.

I need to somehow open a url in private window programmatically

It seems to work if you set Firefox to always start in Private Browsing mode (browser.privatebrowsing.autostart = true)

• Tools > Options > Privacy > Firefox will: "Use custom settings for history": [X] "Always use private browsing mode"

user_pref("browser.privatebrowsing.autostart", true);

@cor-el yes but it is a very lame solution actually it is not a solution

It is a workaround that you can consider because other ways probably aren't possible.

You could reserve a second profile in cases where you need to use the command line if you do not want to do this in the current default profile.

See:

• http://kb.mozillazine.org/Creating_a_new_Firefox_profile_on_Windows
• http://kb.mozillazine.org/Shortcut_to_a_specific_profile
• http://kb.mozillazine.org/Using_multiple_profiles_-_Firefox

You can use the -no-remote command line switch to open another Firefox instance with its own profile and run multiple Firefox instances simultaneously.

• http://kb.mozillazine.org/Opening_a_new_instance_of_Firefox_with_another_profile

@cor-el for a very simple feature, so much work. But it seems this the fault of developers. can't be helped