add incomplete notes on code style
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README.md
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README.md
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@ -44,3 +44,79 @@ this project must be built on a host running Linux.
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if you are not running Linux, use a VM of some sort.
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i personally use VirtualBox running Alpine Linux.
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i have not tried building with WSL2.
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### Code Style
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this project encourages a heretical and horrifying style of code
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for its shell scripts. the intent is to chain `&&`s while facilitating
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trivial re-ordering of lines. for instance, a `RUN` command in a Dockerfile
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(which just executes a line of shell) might look like this:
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```sh
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RUN : \
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&& echo hello \
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&& note() \
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{ : \
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&& printf '\033[1m%s\033[m: %s\n' >&2 \
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noted "$*" \
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;} \
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&& note '\\( o _ o )//' \
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;
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```
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*gratuitous explanation:*
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* 4-space indentation is a must, since at least three characters
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are needed to contain the operators on the left of each line.
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* `:` is akin to the `true` command; it's used as a no-op
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that only sets the most recent exit code (`$?`) to `0`.
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* `\` continues the code to the next line;
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the proceeding newline is removed and ignored.
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this is purely superficial.
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* `&&` is a short-circuiting operator that only evaluates
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its right-hand side when `$?` is `0`. `&&` is preferred
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over a simple semicolon because most programs use a
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non-zero exit code to indicate that an error occurred,
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whereas `;` will continue executing code,
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even in the presence of an error.
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* `||` is like `&&` but only executes when `$?` is *not* `0`.
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**important:** `||` has a lower precedence than `&&`!
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make sure to wrap your `||`s in braces unless you want to
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capture *everything* before it. for instance:
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` && { test -e myfile || touch myfile ;} \`
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* leftmost `&&`s and `||`s are always centered within their 4-space indent.
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* avoid using pipes (`|`) when possible, because only the
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exit code of the final command in any pipe is respected.
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* functions are declared (`()`) on their own line
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without any braces or other commands.
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* `{ :` is used to begin a multi-line block,
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similar to how `RUN :` begins a shell command.
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sadly, the space between the brace and the colon is not optional.
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* ';}` is used to finish a multi-line block.
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this is aligned with the preceeding `&&` and `||` operators.
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thankfully, the space between `;` and `}` is optional.
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* a final `;` is used to finish off the line-continutation.
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this means that every line before it can end with a `\`,
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which simplifies editing. when podman gives you strange errors,
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double-check that you aren't forgetting the final semicolon.
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* redirections are usually specified *before* a final list of arguments.
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this makes skimming code easier when arguments extend across many lines.
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* **TODO:** explain `if cmd  ;then :  ;fi`.
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* **TODO:** explain `for cmd  ;do :  ;done`.
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* **TODO:** explain `while cmd  ;do :  ;done`.
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* **TODO:** explain `test`s.
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