Walkthrough code comments
Use `$OSTYPE` instead of `$MACHTYPE`
`$OSTYPE` is a better descriptor of the operating system. Let's not abuse
the content of `$MACHTYPE` that is meant to describe the architecture.
Unset variables just before exiting
Make sure the anti-recursive checks behave well
Move documentation to README
Option to avoid exporting functions and variables
Avoid unnecessary bashisms
Avoid external processes in `shell_is_*` functions
OS detection without launching external `uname` process
Initial file from Joseph Wecker
Original location: <https://gist.github.com/3320963>.
NH discussion: <https://news.ycombinator.com/item?id=4369485>.
New project bashrc_dispatch