Firefox omni.ja tweaks

A script that directly edits the internal Firefox files stored in the omni.ja and browser/omni.ja archives to customize the behavior of Firefox such as disabling clickSelectsAll, copying automatic URL bar selection to clipboard, etc. This also applies to Firefox ESR.

Where does this script work?

The script works for me. 😉 And I’m running Firefox Nightly on Arch Linux. This is the software setup that I’ve tested — it may work for other setups, too, and this script is likely to work with later versions as well:

• Firefox Nightly 91 (2020-07-01) through 105 (2022-08-14) (64-bit)
• Firefox ESR 78 through 102 (64-bit)
• Arch Linux (core/linux 5.8.1.arch1-1 through 5.18.16.arch1-1)
• Gnome Desktop (extra/gnome-desktop 1:3.36.5-1 through 1:42.4-1)
• Bash 4.x+
• Info-ZIP UnZip (extra/unzip 6.0-14 through 6.0-18)
• Info-ZIP Zip (extra/zip 3.0-9 through 3.0-10)

Note: the versions will only be updated for substantial changes to the script.

How to run the script?

The script applies changes to a set of Firefox install paths; it needs to be executed after an update of the Firefox install paths. It should not be executed a second time before another Firefox update.

The script automatically modifies the omni.ja files and the browser/omni.ja files, and clears the browsers’ startup caches and creates .purgecaches files, in order to assure that the changes are properly applied when starting Firefox.

This step-by-step guide describes default script execution, i.e. without any presets or options passed. You can use the web app to choose custom presets for the script or pass options listed below.

Also see my Super User answer for detailed steps.

Before using the script for the first time

1. Download the script from the original source.
2. Set the script as a runnable file.

Before running the script

3. Update all Firefox browsers you want to fix and start each Firefox browser so they install all the updates properly.
4. Close all Firefox browsers you want to fix.

Running the script

5. Execute the script.

   • Interactively: Either click it in your file manager, then click the Run in terminal button, or run it directly as e.g. bash ./fixfx.sh.
   • Non-interactively: Click it in your file manager, then click the Run button (i.e. running in background; no terminal shown).

   Interactive execution is recommended.

6. The script should find your Firefox install path(s) automatically. If multiple viable paths are found, you can select the ones you want to fix. If no paths are found, you can either

   • call the script with the --firefox option, specifying the Firefox install paths, or
   • use the web app to download a version of the script with the paths specified in the presets.

   The correct paths contain an omni.ja file, as well as a browser directory with another omni.ja file in it.

7. The script checks if you have write access to all relevant directories: the Firefox install paths, the backup path, and /tmp, where the unzipping happens. If not, you’ll be asked to enter your root password. You can also run the script with sudo instead.
8. All specified Firefox paths are processed:
   1. A backup of the internal application resources (omni.ja and browser/omni.ja) of your Firefox installation is created (in /tmp, by default).
   2. After a few moments, you should be able to launch the processed Firefox browser normally. If everything went well, you can now test your browser with an improved user experience! Press Enter to exit.
   3. However, if the Firefox browser won’t run properly, close Firefox, and restore the backup by typing r and Enter. The backup will be restored. Start Firefox again to go back to normal.
   4. Repeat for the next Firefox path; at the end, the script will exit.

Let me know if something went wrong by creating a new issue. Provide details about terminal output, your system setup, and your software versions.

Since this script partially relies on Firefox making sure to use the newly changed omni.ja and browser/omni.ja, as opposed to a cached version of these files, additional care must be taken to make issues reproducible. See the wiki about the startup cache to gain insight into the cache clearing mechanism.

You may some day receive a warning about a pattern failing to match due to the original Firefox code having changed. Please report these warnings as well.

Restoring the backup

The script offers an opportunity to test Firefox and restore the backup in case something went wrong. It also tells you which file paths are being used and tells you the command lines for restoring the backup, if not already applied.

If you need to restore the backup later on, you can type commands into the terminal which are based on the following snippet. Check if you need to run this as root, and double-check the file paths.

firefox_dir=$(whereis -b firefox | cut -d ' ' -f 2)          # Or put the correct path here, like `firefox_dir=/usr/lib/firefox`.
                                                             # `cut -d ' ' -f 2` just takes the first path found, which might not be the right one.
cp -p /tmp/omni-n.ja~ "$firefox_dir/omni.ja"                 # Replace `n` by the incremental number of the backup file name.
cp -p /tmp/browser_omni-n.ja~ "$firefox_dir/browser/omni.ja" # Replace `n` by the incremental number of the backup file name.
touch "$firefox_dir/browser/.purgecaches"                    # This is necessary only here. A "$firefox_dir/.purgecaches" is ignored.

Using the web app

The web app lets you choose all the options and tweaks that you want and put them into a customized shell script as presets.

Once you’ve downloaded the customized script, set it as a runnable file, make sure Firefox is up-to-date and closed, and then run the script (steps 2, 3, and 4). The script should then run exactly as specified. You can make sure if the presets are set correctly: they’re in the settings array between # Begin presets. and # End presets..

You can theoretically still pass command line options to the script; these will get additionally applied. For example, if you specified a firefoxDirs|0 in the web app, passing another -f directory will add it as firefoxDirs|1. Opt-in options such as -q, -a, or -y cannot be disabled once they’ve been enabled. A -b or -o option is overridden by a later instance of the same option.

Running the web app

If you fork this repo, the web app can be served using a simple HTTP server, e.g. http-server from NPM.

Options in detail

As usual, short options can be combined, e.g. -qyab '/tmp' which expands into -q -y -a -b '/tmp'. A -- marks the end of options, meaning every option after that will be ignored. There are no positional arguments for this script, so in fact, after --, everything is ignored.

• -f DIR, --firefox DIR

  Adds DIR to the collection of Firefox install paths that are to be fixed. Can be used multiple times: -f DIR1 -f DIR2, etc.

  Note that DIR must include an omni.ja file and a browser/omni.ja file. If it doesn’t, the path is ignored.

  You can use this together with -a to add all automatically found paths to the collection.

• -a, --add-all-found

  Automatically find all Firefox install paths and add them to the collection of Firefox install paths that are to be fixed.

  If neither -f nor -y are passed, the script acts as if the option is enabled by default, with one exception: the script will interactively prompt for a choice of Firefox paths if and only if

  • more than one path is found, and
  • an interactive prompt hasn’t already occured, and
  • the script is executed interactively, and
  • -q is not passed, and
  • -a is not passed, and
  • -y is not passed, and
  • -f is not passed.

  In other words, the script attempts to fix all Firefox paths by default, but since this isn’t requested explicitly, the script will ask, if possible.

• -y, --fix-only-youngest

  Pick only the Firefox install path from the collection with the most recent modification / install date, to be fixed.

• -o FIX_OPTION, --option FIX_OPTION

  Choose which functionality you want to change in the internal files. Can be used multiple times: -o FIX_OPTION1 -o FIX_OPTION2, etc.

  FIX_OPTION can have a few different forms:

  • To turn the option yourOptionHere off, use yourOptionHere= (e.g. --option preventClickSelectsAll= or -o preventClickSelectsAll=). This sets the option entry’s value to an empty string, which acts as a false value in Bash.
  • To turn the option yourOptionHere on, just type yourOptionHere by itself, or with any other substring after = (e.g. -o preventClickSelectsAll or -o preventClickSelectsAll=true).
  • To supply a custom value, use yourOptionHere=yourValueHere.

  See the available options below. Unrecognized options are ignored.

• -b DIR, --backup DIR

  Stores backup of internal Firefox files omni.ja and browser/omni.ja in DIR.

  DIR must either point to an existing directory, or its parent directory must exist. DIR pointing to anything other than a directory is not allowed. One directory is automatically created if not yet existing.

  Incremental files like omni-0.ja~, omni-1.ja~, etc., and browser_omni-0.ja~, browser_omni-1.ja~, etc. are created within that directory.

  Omitting this option defaults to backups being stored in /tmp.

• -q, --quiet

  Only errors (specifically, anything echo’d to STDERR) will be logged. Normal (STDOUT) output will be suppressed. This will also suppress asking for confirmation.

  By default, output will be emitted, but if the script was not executed in an interactive terminal, all interactive selections or confirmation questions are suppressed, regardless of whether the --quiet option was passed or not. Note that these tests aren’t perfect and that they can break using some file descriptor redirection, but it should cover most basic cases of executing this script.

• -h, -?, --help, --?

  If this option is present, the help information is printed, and the script exits. The help text contains contextual information such as the path name of the script source, the default options, etc.

Interaction between -a, -f, -q, and -y

Based on the options passed to the script, the script will first collect certain Firefox paths (e.g. the specified ones from -f, or the automatically found ones), then filter them (e.g. the most recent modification date using -y, or all of them). The script will only process the filtered set of Firefox paths.

Available options

Examples

We’ll assume that the script is callable via ./fixfx.sh. The exact path and file name depends on where you placed the file.

• The following command fixes a specific Firefox installation located under /usr/lib/firefox-de_DE and creates an incremental backup of the original omni.ja files in /tmp. The specified directory must contain an omni.ja and a browser/omni.ja.

  ./fixfx.sh --firefox /usr/lib/firefox-de_DE

• This command fixes a set of automatically determined Firefox installations, while creating a backup of omni.ja and browser/omni.ja in the specified directory. The file names are incremental, e.g. omni-0.ja~, omni-1.ja~, etc.

  ./fixfx.sh -b /home/user/backups/my_firefox_backups

• This command enables the behavior where double-clicking a URL bar selects the entire URL, but not a single click.

  ./fixfx.sh -o preventClickSelectsAll -o doubleClickSelectsAll

  If you want both click behaviors and preventClickSelectsAll is the default in your script (see ./fixfx.sh -h to check), use this instead:

  ./fixfx.sh -o preventClickSelectsAll= -o doubleClickSelectsAll

Exit status

The script distinguishes between four different status codes when exiting. Error codes (i.e. status codes greater than 0) are usually accompanied by an error message printed to STDERR.

• 0 for success: everything went as expected, the script terminated successfully.
• 1 for general failure due to utilities used in the script: e.g. some file was not found, some directory could not be created, directory navigation failed, unzipping or zipping the omni.ja failed, read or write permissions could not be granted, etc.
• 2 for incorrect script usage: e.g. --backup, --firefox, or --option used without values, the specified Backup directory isn’t an existing directory, no valid Firefox path found, etc.
• 130 if the script process was terminated (e.g. via Ctrl+C) or killed.

A brief history of the scope of this repository

See this answer on Super User for full context and an explanation of the script. The repo’s URL used to be https://github.com/SebastianSimon/firefox-selection-fix.

Various browsers have started adopting a particular behavior when clicking the address bar: the entire URL is selected. This goes against good UX practices. In Firefox, there used to be the preferences browser.urlbar.clickSelectsAll, browser.urlbar.update1, and browser.urlbar.update2 to control this behavior and other updates, but the latter two were always expected to be temporary.

Around March 2020, the browser.urlbar.clickSelectsAll preference has been removed. Since then, this bug has been under discussion, where a patch has been suggested — this would involve recompiling Firefox from scratch. As the “clickSelectsAll doesn’t work” duplicates accumulate on Bugzilla to this day, one of these has received a comment by Stephen McCarthy which describes a workaround that involves editing internal Firefox files. This workaround looks like the simplest approach, but the approach didn’t work as-is.

This repo provides a script that attempts to give us users the browser.urlbar.clickSelectsAll = false experience back.

I realized the potential of this script: it could also be used to change any aspect of Firefox’s behavior, not just this selection behavior. Indeed, several months later, some users have requested a few other features, so I started including new features and customization options. Since then, the repo has been renamed to its current name.