Control the Firefox Browser With 'About' Commands

firefox about commands
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This article is only intended for users running the Mozilla Firefox browser on Linux, Mac OS X, macOS Sierra, or Windows operating systems.

Firefox's address bar, also known as the Awesome Bar, allows you to enter the URL of your desired destination page. It functions as a search bar as well, letting you submit keywords to a search engine or website. Your past browsing history, bookmarks and other personal items are also searchable via the Awesome Bar.

Another powerful feature of the address bar lies in the ability to navigate the browser's preferences interface as well as dozens of behind-the-scenes settings by entering predefined syntax. These custom commands, several which are listed below and are usually preceded by 'about:', can be utilized to take complete control of your Firefox browser.

General Preferences

To access Firefox's General preferences, enter the following text in the address bar: about:preferences#general. The following settings and features are found within this section.

  • Designate Firefox as your default browser
  • Define Firefox's startup behavior each time it is launched
  • Change your home page
  • Modify the location where downloaded files are saved
  • Configure Firefox's tabbed browsing settings

Search Preferences

Firefox's Search preferences are accessible by typing the following text into the address bar: about:preferences#search.

The following search-related settings are available on this page.

  • Set Firefox's default search engine to one of several preinstalled options
  • Enable/disable search suggestions from within the Awesome Bar
  • Modify individual search engine settings for Firefox's One-Click Search feature
  • Install new search engines or delete existing options

    Content Preferences

    Enter the following text into the address bar to load the Content preferences interface: about:preferences#content. The options below will be displayed.

    • Instruct Firefox whether or not to play DRM-controlled audio and video content within the browser
    • Control how the browser handles Push Notifications
    • Manage Firefox's integrated pop-up blocker
    • Modify the browser's default font style and size as well as background, text and link color designations
    • Choose from dozens of preferred languages to display Web page verbiage

    Applications Preferences

    By entering the following syntax in the Awesome Bar, Firefox allows you to specify what actions should be taken each time a certain file type is opened: about:preferences#applications. An example would be associating the Preview in Firefox action with all PDF files.

    Privacy Preferences

    To load Firefox's Privacy preferences in the active tab, enter the following text in the address bar: about:preferences#privacy. The options listed below are found on this screen.

      Security Preferences

      The Security preferences below are accessible via the following address bar command: about:preferences#security.

      • Enable/disable warnings whenever a website attempts to install an add-on
      • By default, Firefox will block content it deems dangerous and/or deceptive; these restrictions can be disabled on this page
      • Manage stored login information, including usernames and passwords
      • Enable and configure a Master Password

      Sync Preferences

      Firefox provides the ability to synchronize your browsing history, bookmarks, saved passwords, installed add-ons, open tabs, and individual preferences across multiple devices and platforms.

      To access the browser's sync-related settings, type the following into the address bar: about:preferences#sync.

      Advanced Preferences

      To access Firefox's Advanced preferences, enter the following in the browser's address bar: about:preferences#advanced. There are many configurable settings found here, including those shown below.

      • Toggle accessibility features on and off, including an on-screen touch keyboard
      • Enable/disable autoscrolling, smooth scrolling and hardware acceleration
      • Control the level of data that is recorded and shared with Mozilla, including Firefox's Crash Reporter and Health Report
      • Manage Firefox's network settings, including proxy server configuration
      • Modify the amount of space reserved for browser cache
      • Dictate which websites have permission to store offline Web content on your computer for future use
      • Configure how and when browser or search engine updates are downloaded and installed
      • Access Firefox's Certificate and Device Manager interfaces

      Other about: Commands

      • about: Displays versioning and licensing details for your specific Firefox build
      • about:addons: Launches Firefox's Add-On Manager, where you can control all installed extensions, themes and plugins.
      • about:buildconfig: Shows build source, platform details, configuration options, and other information about your Firefox application
      • about:cache: Provides in-depth details about memory allocation, disk and application cache including number of entries, location and usage data
      • about:crashes: Lists all crash reports that have been submitted to Mozilla
      • about:credits: Shows a lenghty list of people who have contributed to Mozilla, in alphabetical order
      • about:downloads: Displays a record of files downloaded through the browser; including filename, size, origin site, and date/timestamp
      • about:home: Loads the Firefox Start Page in the active tab.
      • about:healthreport: Opens the Firefox Health Report, a detailed interface that shows low-level performance information about your specific version of Firefox
      • about:license: Presents the Mozilla Public License (MPL) as well as dozens of other open source licenses applicable to the browser
      • about:logo: Displays the current Firefox logo, centered upon a solid black background
      • about:memory: Lets you measure the browser's memory usage and save either concise or verbose reports for analysis purposes
      • about:mozilla: Launches a hidden Easter egg that shows a quote taken from the fictitious 'Book of Mozilla'
      • about:networking: Details network connections made within the browser, broken down into several categories (HTTP, Sockets, DNS, WebSockets)
      • about:newtab: Opens Firefox's New Tab page, containing thumbnail images of your top sites.
      • about:plugins: Lists all plugins installed in Firefox including versioning information, file path, current state, and description
      • about:rights: Explains your individual rights as a Firefox user
      • about:robots: Another Easter Egg, showing some fun and frightening facts about robots
      • about:sessionrestore: Allows you to restore the previous browsing session, reopening tabs and windows that may have been inadvertently shut down
      • about:support: Provides a bounty of technical information about your Firefox installation, its accompanying add-ons and much more
      • about:telemetry: Opens a page that displays hardware, performance, usage, and customization data collected by Telemetry and submitted to Mozilla (if enabled)

      The about:config Interface

      The about:config interface is very powerful, and some modifications made within it could have serious effects on both your browser and system's behavior. Proceed with caution. First, open Firefox and type the following text in the browser's address bar: about:config.

      Next, hit the Enter key. You should now see a warning message, stating that this may void your warranty. If so, click on the button labeled I accept the risk.

      Below is just a small sampling of the hundreds of preferences found within Firefox's about:config GUI. 

      • app.update.auto: Firefox's default behavior is to automatically download and install updates to the browser whenever they are available. These updates not only serve to enhance Firefox's functionality but also to patch vulnerabilities. From a security standpoint alone, it is recommended that you leave the auto-update feature enabled. However, it can be disabled by changing the value of this preference to false.
      • browser.anchor.color: Defines the hex color value of Web page links that have yet to be clicked on. The default color, blue, is represented by #0000EE. This preference, like many others, can be overridden by the site itself.
      • browser.cache.disk.enable: Enabled by default, this preference dictates whether or not Firefox stores cached images, text and other Web page content on your hard drive to speed up page load times on subsequent visits. Double-click on this preference to toggle cache on and off.
      • browser.formfill.enable: The Autofill feature in Firefox can come in very handy when you're asked to enter the same information over and over again into Web forms, such as your name and address. The browser stores some of this data for the purpose of prepopulating it the next time it is requested. By setting this preference to false, Firefox will no longer save these potentially sensitive items.
      • browser.privatebrowsing.autostart: Firefox provides the ability to enter Private Browsing Mode to ensure that history, cache, cookies and other private data components are not stored on your local hard drive at the end of a browsing session. If you'd like the browser to automatically enter private mode each time the application is launched, set the value of this preference to true.
      • browser.shell.checkDefaultBrowser: Each time Firefox is launched, you may notice that you are asked whether or not you would like to designate it as the default browser (of course, unless, it is already set as the default). If you'd like to disable these notifications from appearing, modify the value of this preference to false.
      • browser.tabs.warnOnClose: If you have multiple tabs open and attempt to close Firefox, a pop-up dialog will appear asking you to confirm that you'd like to close all open tabs. This safety net can come in handy, but can also be an annoyance. To hide this warning and allow Firefox to close all tabs automatically, change this preference's value to false.
      • extensions.update.interval: As mentioned above, Firefox checks on a regular basis to see if an updated version is available. The same logic applies for browser extensions, assuming that you have not disabled this functionality in the past. This particular preference dictates the amount of time allowed to pass between checking for extension updates, measured in milliseconds.