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README.md

Bash Command Template

This is a GitHub template repo that will be copied instead of forked to create a new Bash command with a command something like this:

gh repo create rwxrob/mycmd -p rwxrob/template-bash-command

Obviously, not all of this is needed for many Bash scripts, but anything with more than two subcommands will benefit from the builtin tab completion, embedded Markdown help documentation support, and included functions (usage, _filter, _buffer, _have, etc.)

Installation

It's usually easiest to install by cloning the repo and adding the full path to this repo to your PATH. That way you can keep up with updates.

Naming Conventions

Name repos containing single bash commands with cmd-
Name template repos beginning with template-
Start command functions with command_ to be completed
Start command functions with command__ to not be completed

Usage

command
command usage
command help [<cmd>]
command foo [<arg>]
command bar [<arg>]

Commands

Command	Summary
usage	Display single line summary of all command usage
help	Display help information
foo	Do the foo
bar	Do the bar

`usage`

The usage command displays a summary of usage.

`help`

The help command prints help information. If no argument is passed displays general help information (main). Otherwise, the documentation for the specific argument keyword is displayed, which usually corresponds to a command name (but not necessarily). All documentation is written in CommonMark (Markdown) and will displayed as Web page if pandoc and $HELP_BROWSER are detected, otherwise, just the Markdown is sent to $PAGER (default: more).

`foo`

The foo command foos.

`bar`

The bar command bars.

Dependencies

Required:

Bash 4+

Optional:

pandoc - for rich help docs

Justification

Bash is the dominate shell scripting language and the official default Linux interactive shell, which reduces cognitive overhead; every command line is a line of code that could be put into script as is. Bash scripts are at the core of cloud, containers, and Kubernetes. Bash 4+ with its associative array support, powerful regular expressions, and multiple ways of feeding data to loops easily covers the needs previously requiring Python and Perl scripts. Bash scripts are also much more powerful, safer, flexible, and performant than POSIX shell or Zsh.

Caveats

Use the official bash path: #!/usr/bin/bash
Using #!/usr/bin/env bash introduces unnecessary risk
Always set the acceptable PATH at beginning of script
Always check script with shellcheck before releasing
Always use bc for any floating point math