Firefox/CommandLineOptions

[Work in progress]

User profile

-allow-downgrade

Firefox 67's downgrade protection prevents accidentally starting Firefox in a profile running a later version of Firefox. Depending on changes between the two versions, some files in a profile may not be downwards compatible. Adding this option bypasses downgrade protection.

-CreateProfile profile_name

Create a new profile in the default directory, but do not start the application. The profile will be named profile_name in the profile manager, the profile_name must not contain spaces ( ). Do not run profile_name while running an instance of the application, you can use the -no-remote option to avoid connecting to a running instance.

firefox -CreateProfile JoelUser

-CreateProfile "profile_name profile_dir"

Creates a new profile in the profile_dir directory, but do not start the application. The profile will be named profile_name in the profile manager. Note profile_name and profile_dir are quoted together, and are separated by exactly 1 space (as with the previous syntax, profile_name must not contain spaces).

Do not run profile_dir while running an instance of the application. You can use the -no-remote option to avoid connecting to a running instance.

firefox -CreateProfile "JoelUser c:\internet\joelusers-moz-profile"

Note: profile_dir must not exist and you must not already have a profile called profile_name.

-migration

Start with import wizard.

-new-instance

Open new instance, not a new window in running instance, which allows multiple copies of application to be open at a time.

firefox -new-instance -P "Another Profile"

Note: Not available for Windows; see bug 855899.

-no-remote

Do not accept or send remote commands. Implies -new-instance.

firefox -no-remote -P "Another Profile"

Note: Since Firefox 9, this does really mean what its name implies on all platforms. i.e. instances created with this parameter do not accept or send remote commands, see bug 650078. That means that such instances won't be re-used. Also when using this argument a new instance is created in any case.

-override /path/to/override.ini

Load the specified override.ini file to override application.ini (browser/app/application.ini). This can be used to suppress the migration wizard at startup by loading the following override.ini. Firefox only.

[XRE] EnableProfileMigrator=0

-ProfileManager

Start with profile manager. Short form: -P without a profile name.

-P "profile_name"

Bypass profile manager and launch application with the profile named profile_name. Useful for dealing with multiple profiles.

firefox -P "Joel User"

Note: profile_name is case sensitive. If you don't specify a profile name then the profile manager is opened instead. You must use an upper case P on Linux with versions older than 7.x, as there lower case invokes purify mode (memory and leak detection). Other platforms accept both upper and lower case.

-profile "profile_path"

Start with the profile with the given path. Firefox, Thunderbird and SeaMonkey2.x only.

"profile_path" can either be an absolute path ("/path/to/profile") or a relative path ("path/to/profile").

Note: On macOS, specifying a relative path is not supported anymore from Firefox 4.0 and up due to a regression; see bug 673955.

Browser

-browser

Start with the browser component. Firefox and SeaMonkey only.

-foreground

Make this instance the active application.

-headless

Runs Firefox in headless mode, which is very useful for purposes such as debugging and automated testing. Available in Firefox 55+ on Linux, and Firefox 56+ on Windows/Mac OS X.

-new-tab URL

Open URL in a new tab. Firefox and SeaMonkey2.x only.

-new-window URL

Open URL in a new window. Firefox and SeaMonkey2.x only.

--kiosk URL

Open URL full screen without user interface. Firefox 71 and later.

-preferences

Open options/preferences window. Firefox and SeaMonkey2.x only.

-private

Opens Firefox in permanent private browsing mode. Firefox 3.6 and later only.

May not be applicable in older Ubuntu for Firefox 20 and later, confirmed to work in 14.04.

-private-window

Opens a new private browsing window in an existing instance of Firefox. Firefox 20 and later only.

-private-window URL

Open URL in a new private browsing window. If a private browsing window is already open, a new tab is opened in the existing window. Firefox 29 and later only. Does not work in Firefox 31 on linux mint 17 nor on Firefox 48 on Windows 7. URL opens in a non-private window.

-search term

Search term with your default search engine. Firefox and SeaMonkey 2.1 and later only.

-setDefaultBrowser

Set the application as the default browser. Firefox only.

-url URL

Open URL in a new tab or window, depend on the browser option. -url can be omitted. You may list multiple URLs, separated by spaces. Firefox and SeaMonkey only.

Note: When opening multiple URLs, Firefox always opens them as tabs in a new window.