Set locked preference values in Firefox (this guide applies to Linux)

set_locked_prefs_in_firefox.md

Set my default settings in Firefox

First install dos2unix

This piece of software will convert unix-like text-files to Windows-like text-files, and is recommended by Mozilla when using this method. I have however found that it will work using plain utf8 and unix line-endings (FF 63+).

Now create a file called FIREFOX_INSTALL_DIRECTORY/defaults/pref/local-settings.js with the content:

pref("general.config.filename", "mozilla.cfg");
pref("general.config.obscure_value", 0); // use this to disable the byte-shift

Then create a file called FIREFOX_INSTALL_DIRECTORY/mozilla.cfg with your own personal (locked) settings:

Warning: These are my own settings and will pbly not work for you!

//
pref("browser.startup.homepage", "https://duckduckgo.com/");
lockPref("apz.zoom_animation_duration_ms", 0);
lockPref("browser.cache.disk.capacity", 999999);
lockPref("browser.cache.disk.parent_directory", "/media/elundmark/usbext4/mozilla");
lockPref("browser.cache.disk.smart_size.enabled", false);
lockPref("browser.urlbar.searchSuggestionsChoice", false);
lockPref("browser.urlbar.suggest.searches", false);
lockPref("dom.ipc.processCount", 1);
lockPref("font.name.monospace.x-western", "Courier New");
lockPref("font.name.sans-serif.x-western", "Arial");
lockPref("font.name.serif.x-western", "Times New Roman");
lockPref("font.size.fixed.x-western", 13);
lockPref("image.animation_mode", "once");
lockPref("media.autoplay.enabled", false);
lockPref("media.encoder.webm.enabled", false);
lockPref("media.ffmpeg.enabled", false);
lockPref("media.flac.enabled", false);
lockPref("media.mediasource.webm.audio.enabled", false);
lockPref("media.mediasource.webm.enabled", false);
lockPref("media.mp4.enabled", false);
lockPref("media.ogg.enabled", false);
lockPref("media.ogg.flac.enabled", false);
lockPref("media.opus.enabled", false);
lockPref("media.peerconnection.enabled", false);
lockPref("media.wave.enabled", false);
lockPref("media.webm.enabled", false);
lockPref("mousewheel.with_alt.action", 4);
lockPref("mousewheel.with_control.action", 4);
lockPref("mousewheel.with_win.action", 4);
lockPref("network.dns.disablePrefetch", true);
lockPref("network.predictor.enabled", false);
lockPref("plugin.disable_full_page_plugin_for_types", "application/pdf");
lockPref("privacy.donottrackheader.enabled", true);
lockPref("privacy.trackingprotection.enabled", true);
lockPref("toolkit.cosmeticAnimations.enabled", false);
lockPref("media.webspeech.recognition.enable", false);
lockPref("camera.control.face_detection.enabled", false);
lockPref("dom.imagecapture.enabled", false);
lockPref("geo.enabled", false);
lockPref("browser.sessionhistory.max_entries", 20);
lockPref("media.ffvpx.enabled", false);
lockPref("media.default_volume", "0.8");
lockPref("media.autoplay.block-webaudio", true);
lockPref("media.autoplay.ask-permission", true);
lockPref("extensions.pocket.enabled", false);
lockPref("app.shield.optoutstudies.enabled", false);
lockPref("extensions.getAddons.cache.enabled", false);
lockPref("browser.safebrowsing.downloads.enabled", false);
lockPref("browser.safebrowsing.malware.enabled", false);
lockPref("browser.safebrowsing.phishing.enabled", false);
lockPref("browser.safebrowsing.passwords.enabled", false);
lockPref("browser.newtab.preload", false);
lockPref("network.preload", false);
lockPref("beacon.enabled", false);
lockPref("browser.send_pings", false);
lockPref("dom.battery.enabled", false);
lockPref("media.video_stats.enabled", false);
lockPref("media.navigator.video.enabled", false);
lockPref("media.peerconnection.video.enabled", false);

These settings are my default ones, and will make Firefox safer, and incapable to play any audio or video.

Finally set the files you created to ANSI:

$ unix2dos -1252 -- FIREFOX_INSTALL_DIRECTORY/mozilla.cfg $ unix2dos -1252 -- FIREFOX_INSTALL_DIRECTORY/defaults/pref/local-settings.js

I have found that skipping this step still works in FF 63+, but to be safe you might as well do it.