The default web browser in Debian's GNOME environment is Firefox.
The default web browser in Debian's KDE environment is Konqueror.
These can be changed to fit your needs. If you prefer a different browser (e.g. Chromium), read below to find out how to change it in your preferred desktop.
- Foreign applications
- Removing alternative browsers from the system
- Opening the default browser from a script
Default for GNOME sessions (user-specific)
In the Default Applications section of the GNOME Settings, you can set your default web browser for your user in the "Web" dropdown.
Default for GNOME sessions (system-wide)
The default GNOME browser can be changed for the whole system by reconfiguring the alternative.
# update-alternatives --config gnome-www-browser
Default for KDE sessions (user-specific)
Under System Settings > Applications > Default Applications > Web Browser, change the "Open http and https URLs" setting to "in the following application" and choose your preferred browser from the dropdown list, then apply the change.
To change how htm or html files are handled when they are clicked in your file manager, change the preference under System Settings > Applications > File Associations, then search for "html" in the filetype search bar at the top. Under the "text" category, the "html" item lets you set the application preference in order. Move your favorite browser to the top.
Default for foreign programs (system-wide)
Programs which are not designed for the user's desktop environment do not obey the browser settings of the desktop environment (GNOME or KDE). For example, Thunderbird ignores desktop environment-specific browser settings. The default browser for generic applications can be changed for the whole system by reconfiguring the x-www-browser alternative.
# update-alternatives --config x-www-browser
Default for foreign programs (user-specific)
Some applications use xdg-open (part of xdg-utils). xdg-settings can be used to both get and change the default browser. Local settings can also be found in the users' home in ~/.config/mimeapps.list.
$ xdg-settings get default-web-browser chromium.desktop
$ xdg-settings set default-web-browser firefox-esr.desktop
Removing alternative browsers from the system
This method involves removing all the other browsers installed on the system, so that the desired one remains the only one. Sometimes this is not feasable (multiuser system, dependencies) and is the least elegant.
Any of the previous methods is preferred to this one, but this method can be useful for lightweight systems.
Opening the default browser from a script
If you're writing a script or application for Debian that needs to be able to open the default browser, your best option is to use thesensible-browser wrapper from the sensible-utils package. This tests the common symlinks (x-www-browser, gnome-www-browser, www-browser, etc.) and chooses the most "sensible" browser out of them.
The environment variable BROWSER can be set to override its selection and force it to always choose your desired browser.