bashvar

bashvar is a small Ruby library that parses the output produced by running the following Bash snippet:

compgen -v | while read -r var; do declare -p "$var" 2>/dev/null; done

It provides a robust, dependency-free way to marshal Bash variables into Ruby data structures.

Project Origin

This library was initially scaffolded with assistance from Google Gemini CLI. All code has been reviewed and modified by human contributors. See LICENSE (MIT) for terms.

Installation

Add this line to your application's Gemfile:

gem 'bashvar'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install bashvar

Usage

First, capture your Bash variables into a file (e.g., /tmp/bash_vars.txt):

echo "$(compgen -v | while read -r v; do declare -p "$v" 2>/dev/null; done)" > /tmp/bash_vars.txt

Then, parse them in Ruby:

require "bashvar"

input = File.read("/tmp/bash_vars.txt")
vars  = BashVar.parse(input)

puts vars["HOME"]
puts vars["PATH"]

# Example for array/hash variables
require 'pp' # For pretty printing
pp vars["LIST"] if vars.key?("LIST")
pp vars["MAP"] if vars.key?("MAP")

Supported Bash Declarations → Ruby Types

Bash Flags	Example `declare -p` line	Ruby Value Type	Notes
`--` (none), `-x`, `-r`, combos w/out `a`, `A`, `i`	`declare -- HOME="/home/u"`	`String`	Attribute flags ignored for value type. Export/readonly not preserved.
`-i`	`declare -i COUNT="42"`	`Integer` (if parseable) else `String`	Numeric conversion best‑effort via `Integer()`; fallback to raw decoded string.
`-a`	`declare -a LIST='([0]="a" [1]="b")'`	`Array<String>`	Indices respected; assigning to `result[index] = value` (Ruby auto-expands & fills `nil`).
`-A`	`declare -A MAP='([k]="v" [x]="y")'`	`Hash<String,String>`	Keys preserved as strings exactly as given inside brackets.

Escapes / Special Characters

Double‑quoted values and ANSI-C quoted ($'...') values emitted by declare -p may contain backslash escapes (e.g., \n, \t, \", \\). These are decoded to their actual characters in the returned Ruby value.

Limitations

Does not preserve attribute metadata (export, readonly, nameref, etc.). Only value typing.
Does not attempt to resolve nameref (-n) targets.
Does not evaluate arithmetic expressions beyond what Bash already evaluated in the declare -p output.
Does not parse function definitions.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/fd00/bashvar.

License

The gem is available as open source under the terms of the MIT License.