Modify configuration files where it makes sense to do so, and ignore the rest.
Table 1-1 in the introduction to Chapter 1 describes the location of the two important file areas that Firefox uses: the install area and the profile area. This hack runs through the files in those two folders, pointing out which ones can be modified for good effect and which ones are pointless to modify. If changes are made to these files using the Firefox GUI, then a restart is rarely required. If files are changed by hand, as described here, then a full restart of the browser is almost always required and is always a sensible policy.
Note that on Windows, the %TMP% directory is also used. The self-extracting Firefox installer temporarily unpacks its files into that directory. On Linux, you must untar non-RPM install bundles by hand to an arbitrary temporary directory before install. On all operating systems, OS files, or at least desktop files, are also touched during install.
Many of the following files can be modified with a simple text editor, although few are designed with that in mind. Of the rest, mostly binary files, small tools exist that can expose their content. To get these tools, either compile Firefox [Hack #93] or explore the contents of a nightly build [Hack #92] .
The preference system [Hack #23] spans the install and profile areas. It is not discussed in detail here.
Here is a breakdown of the install-area subdirectories. ...