You'd like to know just what the heck is with all the initialization, or rc, files.
Here's the cheat sheet for files and what do with them. Some or all of these files may be missing from your system, depending on how it is set up. Systems that use bash by default (e.g., Linux) tend to have a complete set; systems that use some other shell by default are usually missing at least some of them.
Global login environment file for Bourne and similar login shells. We recommend you leave this alone unless you are the system administrator and know what you are doing.
Global environment file for interactive bash subshells. We recommend you leave this alone unless you are the system administrator and know what you are doing.
If this exists, it's almost certainly the configuration file for Ian Macdonald's programmable completion library (see Improving Programmable Completion, "Improving Programmable Completion"). We recommend looking into it—it's pretty cool.
Global GNU Readline configuration. We recommend tweaking
this as desired for the entire system (if you are the
administrator), or tweaking ~/.inputrc for
just you (Getting Started with a Custom Configuration,
"Getting Started with a Custom Configuration"). This is not
executed or sourced but read in via Readline and
bind -f). Note that it may contain
include statements to other ...