apt-get install firefox

You can set different Useragents (about:config) via configfile

Change to the dir, the defaultname is different for everybody

cd /home/<USERNAME>/.mozilla/firefox/*default/

The default config is located in “prefs.js” which should not be edited, you can create the file “user.js” to add your own settings. Example Useragents:

user_pref("general.useragent.override", "Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:59.0) Gecko/20100101 Firefox/59.0");
user_pref("general.useragent.override", "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:69.0) Gecko/20100101 Firefox/69.0");
user_pref("general.useragent.override", "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:70.0) Gecko/20100101 Firefox/70.0");

Start firefox without GUI

firefox -headless https://lunetikk.de