We covered a lot in this series, including:
- What dotfiles and dot directories are
- What version management is, and why it matters
- What shims are
- What a shebang is
- What the
$PATH variable is, and how it's used
- How to read and modify UNIX's file permissions
- What the internal field separator (aka
$IFS) is, and what it's useful for
- How to look up documentation on our machine, using both the
man and help commands
- What a shell is
- What POSIX is
- What a "builtin" command is
- How to find out which shell is your machine's default
- What a
.rc file is
- What shell options are, and how to set them with the
set command
- Some common shell options (
set -e and set -x), and what they do
- How to write boolean conditions in a shell script using the
[ or test command
- Some useful flags for
[ ... ] (such as -n and -f).
- Double- vs. single-
= in a shell script
- Single-
[ ... ] vs. double-[[ ... ]] in a shell script
- Using the
$@ symbol to fetch the list of arguments provided to a script
- How to iterate over arguments in a shell script, using a for-loop
- How to write a case statement in Bash
- What
export statements are, and why they're useful
- The difference between shell variables and environment variables
- The
exec command, how it differs from forking, and when to use each one
- What a "process" is
- How to use Github and the repository's git history to figure out *why* the code is the way that it is.
And possibly more, as well. I lost count lol.
I still have more questions!
Such as:
- What happens inside the child process that gets created by the call to
exec at the end of the shim file?
- We still haven't seen the actual logic which picks the right version number, so it must be happening somewhere else. Where does that live, and how does it work?
- We only scratched the surface of what can be done in Bash. What are some other Bash-isms that we can learn from the RBENV codebase?
These and more questions will be answered in the upcoming soup-to-nuts walk-through of the RBENV codebase. By the end of the walk-through, we will have learned:
- how RBENV keeps your Ruby versions separate, organized, and compartmentalized.
- how RBENV implements the "order of precedence" (`shell > script local > cwd local > global`) mentioned here.
- how to patch RBENV's behavior using hooks and plugins.
- how to use common Bash tools like
sed, awk, and command substitution
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