Eu tive um problema inverso - quero que o firefox abra os links, mas evince começou o cromo, não importa o que aconteça.
Eu usei strace -o /tmp/output evince
para ver quais funções são chamadas e encontrei isso no log:
open("/home/koniu/.local/share/applications/firefox.desktop;", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
open("/usr/local/share/applications/firefox.desktop;", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
open("/usr/share/applications/firefox.desktop;", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
open("/home/koniu/.local/share/applications/chromium.desktop", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
open("/usr/local/share/applications/chromium.desktop", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
open("/usr/share/applications/chromium.desktop", O_RDONLY|O_LARGEFILE) = 16
Não faço ideia do motivo de haver um ponto-e-vírgula incluído no firefox.desktop, mas criei /home/koniu/.local/share/applications/firefox.desktop
com o seguinte conteúdo:
[Desktop Entry]
Name=Firefox
Exec=/usr/bin/firefox %U
Terminal=false
X-MultipleArgs=false
Type=Application
Icon=firefox
Categories=Network;WebBrowser;
MimeType=text/html;text/xml;application/xhtml_xml;x-scheme-handler/http;x-scheme-handler/https;
StartupNotify=true
E agora evince
começa firefox
conforme desejado.