root@blackbox:/usr/bin# v firefox*
-rwxr-xr-x 1 root root 113 apr  8 10:12 firefox
lrwxrwxrwx 1 root root  30 mar  8 03:14 firefox-esr -> ../lib/firefox-esr/firefox-esr
lrwxrwxrwx 1 root root  22 mar  8 17:54 firefox-new -> ../lib/firefox/firefox
-rwxr-xr-x 1 root root 113 aug  3  2016 firefox.SAVE_ORIGINAL
root@blackbox:/usr/bin# cat firefox
#!/bin/sh

FIREFOX="$(which firefox)"
[ -x "$FIREFOX.real" ] && exec "$FIREFOX.real" "$@"

exec firefox-new "$@"
root@blackbox:/usr/bin#