For the current version, it's not too bad if you're on a "popular enough" OS. For example, Firefox has a bootstrap.py script for Linux which will install the right packages on either Ubuntu or Fedora Core. See https://developer.mozilla.org/en-US/docs/Mozilla/Developer_g...

https://developer.mozilla.org/en-US/docs/Mozilla/Developer_g... lists the actual set of libraries and whatnot needed; converting those to the relevant package names for the Linux distro of your choice is tedious, but not too hard.

For an old version, things could be more complicated, depending...