I don't think FF can go beyond what is in the FF Broswer itself. Anything beyond that is from 3rd party software that you will use to do what your asking.

That would require to modify this pref:

• browser.cache.disk.capacity

You would have to create a script that can edit prefs.js in the profile folder or possibly use a mozilla.cfg in the Firefox installation folder to set this pref.

See Configuration:

• https://developer.mozilla.org/en-US/Firefox/Enterprise_deployment_before_60

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

You can use the mozilla.cfg file in the Firefox program folder to initialize (set/lock) preferences and run privileged JavaScript code.

The mozilla.cfg file needs to be in the main Firefox program folder (Mac).

These functions can be used in mozilla.cfg:

defaultPref();	// set new default value, requires special data: format for localized prefs
pref();	// set pref, allow changes in current session
lockPref();	// lock pref, disallow changes

This requires a local-settings.js file in the "defaults/pref" folder where the channel-prefs.js file is located that specifies to use mozilla.cfg.

//
pref("general.config.filename", "mozilla.cfg");
pref("general.config.obscure_value", 0);

The mozilla.cfg and local-settings.js files need to start with a comment line (//).

See also:

• http://mike.kaply.com/2012/03/16/customizing-firefox-autoconfig-files/

though the information provided is helpful but i am not well versed with Javascript and still i am not able to understand how to fix browser.cache.disk.capacity to certain value.

can you please provide me the right example of this?

I tired to create two files mozilla.cfg and local-settings.js but getting error while opening firefox this time that unable to read the configuration file

mozilla.cfg : under C:\Program Files (x86)\Mozilla Firefox

// defaultPref("browser.startup.homepage","data:text/plain,browser.startup.homepage=http://google.co.in");

pref("browser.rights.3.shown", true);

lockPref("app.update.enabled", false);

================================

local-settings.js under : C:\Program Files (x86)\Mozilla Firefox\defaults\pref

// pref("general.config.filename", "mozilla.cfg"); pref("general.config.obscure_value", 0);

i used the below script and it is working fine as expected

@echo off

FOR /F "tokens=*" %%R IN ('dir /B /AD "%APPDATA%\Mozilla\Firefox\Profiles\*.default"') DO CALL:write_settings %%R GOTO:EOF

write_settings

DIR "%APPDATA%\Mozilla\Firefox\Profiles\%1\prefs.js" /AA /B if ERRORLEVEL 1 GOTO:EOF

echo user_pref("browser.download.useDownloadDir", false); >> "%APPDATA%\Mozilla\Firefox\Profiles\%1\prefs.js" echo user_pref("browser.tabs.autoHide", false); >> "%APPDATA%\Mozilla\Firefox\Profiles\%1\prefs.js" echo user_pref("browser.cache.disk.capacity", 30000); >> "%APPDATA%\Mozilla\Firefox\Profiles\%1\prefs.js" echo user_pref("dom.disable_open_during_load", false); >> "%APPDATA%\Mozilla\Firefox\Profiles\%1\prefs.js"

ATTRIB -A "%APPDATA%\Mozilla\Firefox\Profiles\%1\prefs.js" GOTO:EOF