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@ -29,23 +29,22 @@ they are reusable as-is in most scripts.
## Goals
Delete-Key-**Friendly**. We propose using [`main.sh`](http://bash3boilerplate.sh/main.sh)
as a base and removing the parts you don't need, rather than introducing packages, includes, compilers, etc.
This may feel a bit archaic at first, but that is exactly the strength of Bash scripts that we want to embrace.
Delete-Key-**Friendly**. In stead of introducing packages, includes, compilers, etc., we propose using [`main.sh`](http://bash3boilerplate.sh/main.sh) as a base and removing the parts you don't need.
While this may feel a bit archaic at first, it is exactly the strength of Bash scripts that we should want to embrace.
**Portable**. We're targeting Bash 3 (OSX still ships
with 3 for instance). If you're going to ask people to install
**Portable**. We are targeting Bash 3 (OSX still ships
with 3 for instance). If you are going to ask people to install
Bash 4 first, you might as well pick a more advanced language as a
dependency.
## Features
- Conventions so that after a while, all your scripts will follow the same, battle-tested structure
- Safe by default (break on error, pipefail, etc)
- Conventions that will make sure that all your scripts will follow the same, battle-tested structure
- Safe by default (break on error, pipefail, etc.)
- Configuration by environment variables
- Simple command-line argument parsing that requires no external dependencies. Definitions are parsed from help info, so there is no duplication
- Simple command-line argument parsing that requires no external dependencies. Definitions are parsed from help info, ensuring there will be no duplication
- Helpful magic variables like `__file` and `__dir`
- 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
- 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
## Who uses b3bp?
@ -54,15 +53,15 @@ dependency.
- [Sourcery Institute](http://www.sourceryinstitute.org)
- [Computational Brain Anatomy Laboratory](http://cobralab.ca/)
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.
We are looking for endorsements! Are you also using b3bp? [Let us know](https://github.com/kvz/bash3boilerplate/issues/new?title=I%20use%20b3bp) and get listed.
## Installation
There are 3 different ways you can install b3bp:
There are three different ways to install b3bp:
### option 1: Download the main template
Use curl or wget to download the source, save as your script, and start deleting the unwanted bits, and adding your own logic.
Use curl or wget to download the source and save it as your script. Then you can start deleting the unwanted bits, and adding your own logic.
```bash
wget http://bash3boilerplate.sh/main.sh
@ -71,22 +70,22 @@ vim main.sh
### option 2: Clone the entire project
Besides `main.sh`, this will get you the entire b3bp repository including a few extra functions that we keep in the `./src` directory.
Besides `main.sh`, this will also get you the entire b3bp repository. This includes a few extra functions that we keep in the `./src` directory.
```bash
git clone git@github.com:kvz/bash3boilerplate.git
```
### option 3: Require via npm
### option 3: Require via npm0
As of `v1.0.3`, b3bp can also be installed as a Node module so you can define it as a dependency in `package.json` via:
As of `v1.0.3`, b3bp can also be installed as a Node module, meaning you can define it as a dependency in `package.json` via:
```bash
npm init
npm install --save --save-exact bash3boilerplate
```
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.
Even though this option introduces a Node.js dependency, it does allow for easy version pinning and distribution in environments that already have this prerequisite. This is, however, entirely optional and nothing prevents you from ignoring this possibility.
## Changelog
@ -94,11 +93,11 @@ Please see the [CHANGELOG.md](./CHANGELOG.md) file.
## Best practices
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.
As of `v1.0.3`, b3bp offers some nice re-usable libraries in `./src`. In order to make the snippets in `./src` more useful, we recommend the following guidelines.
### Function packaging
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:
It is nice to have a Bash package that can not only be used in the terminal, but also invoked as a command line function. In order to achieve this, the exporting of your functionality *should* follow this pattern:
```bash
if [ "${BASH_SOURCE[0]}" != "${0}" ]; then
@ -109,7 +108,7 @@ else
fi
```
This allows a user to `source` your script or invoke as a script.
This allows a user to `source` your script or invoke it as a script.
```bash
# Running as a script
@ -123,23 +122,23 @@ $ my_script some more args --blah
### Scoping
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 which are already prefixed with `arg_`, and functions, over which b3bp poses no restrictions.
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 that are already prefixed with `arg_`, as well as 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 a single equal sign when checking `if [ "${NAME}" = "Kevin" ]`, double or triple signs are not needed.
1. Use two spaces for tabs.
1. Use long options (`logger --priority` vs `logger -p`). If you are on cli, abbreviations make sense for efficiency. Nevertheless, when you are writing reusable scripts, a few extra keystrokes will pay off in readability and avoid ventures into man pages in the future, either by you or your collaborators. Similarly, we prefer `set -o nounset` over `set -u`.
1. Use a single equal sign when checking `if [ "${NAME}" = "Kevin" ]`; double or triple signs are not needed.
### Safety and Portability
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}`.
1. Use `{}` to enclose your variables. Otherwise, Bash will try to access the `$ENVIRONMENT_app` variable in `/srv/$ENVIRONMENT_app`, whereas you probably intended `/srv/${ENVIRONMENT}_app`. Since it is easy to miss cases like this, we recommend to make enclosing a habit.
1. Use `set`, rather than relying on a shebang like `#!/usr/bin/env bash -e`, since that is neutralized when someone runs your script as `bash yourscript.sh`.
1. Use `#!/usr/bin/env bash`, as it is more portable than `#!/bin/bash`.
1. Use `${BASH_SOURCE[0]}` if you refer to current file, even if it is sourced by a parent script. In other cases, 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}`.
## Frequently Asked Questions
@ -163,4 +162,4 @@ Please see the [FAQ.md](./FAQ.md) file.
Copyright (c) 2013 Kevin van Zonneveld and [contributors](https://github.com/kvz/bash3boilerplate#authors).
Licensed under [MIT](https://raw.githubusercontent.com/kvz/bash3boilerplate/master/LICENSE).
You are not obligated to bundle the LICENSE file with your b3bp projects as long
as you leave these references intact in header comments of your source files.
as you leave these references intact in the header comments of your source files.