- Helpful magic variables like `__file`, `__dir`, and `__os`
- Logging that supports colors and is compatible with [Syslog Severity levels](http://en.wikipedia.org/wiki/Syslog#Severity_levels) as well as the [twelve-factor](http://12factor.net/) guidelines
We're looking for endorsement! Are you also using b3bp? [Let us know](https://github.com/kvz/bash3boilerplate/issues/new?title=I%20use%20b3bp) and get listed.
Although this option introduces a Node.js dependency, this does allow for easy version pinning and distribution in environments that already have this prerequisite. But, this is optional and nothing prevents you from ignoring this possibility.
As of `v1.0.3`, b3bp adds some nice re-usable libraries in `./src`. In order to make the snippets in `./src` more useful, we recommend these guidelines.
It's nice to have a Bash package that can be used in the terminal and also be invoked as a command line function. To achieve this the exporting of your functionality *should* follow this pattern:
1. In functions, use `local` before every variable declaration
1. Use `UPPERCASE_VARS` to indicate environment variables that can be controlled outside your script
1. Use `__double_underscore_prefixed_vars` to indicate global variables that are solely controlled inside your script, with the exception of arguments wich are already prefixed with `arg_`, and functions, over which b3bp poses no restrictions.
### Coding style
1. Use two spaces for tabs
1. Use long options (`logger --priority` vs `logger -p`). If you're on cli, abbreviations make sense for efficiency. but when you're writing reusable scripts a few extra keystrokes will pay off in readability and avoid ventures into man pages in the future by you or your collaborators. Similarly, we prefer `set -o nounset` over `set -u`.
1. Use `{}` to enclose your variables in. Otherwise Bash will try to access the `$ENVIRONMENT_app` variable in `/srv/$ENVIRONMENT_app`, whereas you probably intended `/srv/${ENVIRONMENT}_app`. Since it's easy to miss cases like this, we recommend making enclosing a habit.
1. Use `set` rather than relying on a shebang like `#!/usr/bin/env bash -e` as that is neutralized when someone runs your script as `bash yourscript.sh`
1. Use `#!/usr/bin/env bash` as it is more portable than `#!/bin/bash`.
1. Use `${BASH_SOURCE[0]}` if you refer to current file even if it is sourced by a parent script. Otherwise use `${0}`
1. Use `:-` if you want to test variables that could be undeclared. For instance with `if [ "${NAME:-}" = "Kevin" ]`, `$NAME` will evaluate to `Kevin` if the variable is empty. The variable itself will remain unchanged. The syntax to assign a default value is `${NAME:=Kevin}`.
