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Agent skill

Ruby Version Manager

by st0012 in st0012/ruby-skills

Use at session start for Ruby projects (Gemfile, .ruby-version, or .tool-versions present).

MITAuto-check passedBackend & APIs

Install Ruby Version Manager

skills CLI
$ npx skills add st0012/ruby-skills --skill ruby-version-manager -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install st0012/ruby-skills ruby-version-manager --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/st0012/ruby-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/ruby-skills/skills/ruby-version-manager .claude/skills/ruby-version-manager && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
ruby-version-manager
GitHub stars
125
Token cost
~1.3k tokens
SKILL.md length
489 words
Files
5
Skills in repo
3
Repo updated
First seen
Licence
MIT

At a glance

Use at session start for Ruby projects (Gemfile, .ruby-version, or .tool-versions present).

  • Works in 3 steps: Run detect.sh → Parse Output → Execute Ruby Commands
  • Tasks that involve Backend development
  • SKILL.md covers When to Use, Usage, Output Variables and Activation Commands by Manager, plus 3 more sections
  • Runs Shell scripts from its folder; calls rbenv, asdf and bundle

What it does

Ruby Version Manager is an agent skill from st0012/ruby-skills. Use at session start for Ruby projects (Gemfile, .ruby-version, or .tool-versions present). Detect version manager BEFORE running ruby, bundle, gem, rake, rails, rspec, or any Ruby command.

Its SKILL.md is about 1.3k tokens, which your agent loads only when the skill is triggered. The skill folder holds 4 other files (for example `README.md`, `detect-all-managers.sh` and `detect.sh`).

It sits in Backend & APIs, covering Backend development. It works with Ruby. The repository describes itself as: Claude Code plugins for Ruby development. The licence is MIT.

When your agent uses it

  • Tasks that involve Backend development

Example prompts

  • “/ruby-version-manager”

Requirements

  • A Bash shell
  • Docker

Workflow steps

3 steps, taken from the step headings in SKILL.md.

  1. Run detect.sh
  2. Parse Output
  3. Execute Ruby Commands

What it can do on your machine

Read from SKILL.md and the folder at commit b1ea8b5. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Ships script files (Shell), which the agent can run.

    Shell commands in SKILL.md call:

    • rbenv
    • asdf
    • bundle
    • mise
    • ruby
    • gem

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Ruby Version Manager loads about 1.3k tokens when it runs. Until then it costs about 53 tokens; SKILL.md has 489 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~53
When it runs · the whole SKILL.md, loaded when a task matches
~1.3k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from st0012/ruby-skills at commit b1ea8b5, republished under its MIT licence (© st0012). 489 words, ~1,293 tokens.

Download SKILL.mdSave it as .claude/skills/ruby-version-manager/SKILL.md (or your agent's skills folder). This skill also uses 4 other files; get the full folder from GitHub.
name
ruby-version-manager
description
Use at session start for Ruby projects (Gemfile, .ruby-version, or .tool-versions present). Detect version manager BEFORE running ruby, bundle, gem, rake, rails, rspec, or any Ruby command.

Ruby Version Manager Skill

Detects and configures Ruby version managers for proper environment setup.

When to Use

Run detect.sh IMMEDIATELY when:

  • Starting work in a directory with Gemfile, .ruby-version, or .tool-versions
  • Before your first Ruby command (ruby, bundle, gem, rake, rails, rspec, etc.)
  • When switching between Ruby projects

Do NOT wait for commands to fail or user requests. Proactive detection prevents version mismatch errors.

Always chain activation with commands: ACTIVATION_COMMAND && ruby_command

Usage

Step 1: Run detect.sh

Run detect.sh from this skill's directory (path provided by session-start hook).

Step 2: Parse Output

The script outputs key=value pairs:

text
VERSION_MANAGER=rbenv
PROJECT_RUBY_VERSION=3.2.0
VERSION_AVAILABLE=true
ACTIVATION_COMMAND=eval "$(rbenv init -)"
Step 3: Execute Ruby Commands

Chain ACTIVATION_COMMAND with your Ruby command:

bash
eval "$(rbenv init -)" && bundle install
eval "$(rbenv init -)" && bundle exec rspec

Run detect.sh once per project session; reuse ACTIVATION_COMMAND for subsequent commands.

Output Variables

VariableDescription
VERSION_MANAGERDetected: shadowenv, chruby, rbenv, rvm, asdf, rv, mise, or none
VERSION_MANAGER_PATHInstallation path
PROJECT_RUBY_VERSIONVersion required by project
PROJECT_VERSION_SOURCESource file (.ruby-version, .tool-versions, .mise.toml, Gemfile)
RUBY_ENGINEImplementation (ruby, truffleruby, jruby)
INSTALLED_RUBIESComma-separated available versions
VERSION_AVAILABLEtrue/false - whether requested version is installed
ACTIVATION_COMMANDShell command to activate the manager
SYSTEM_RUBY_VERSIONSystem Ruby (when VERSION_MANAGER=none)
WARNINGEnvironment warnings
NEEDS_USER_CHOICEtrue when multiple managers detected without preference
AVAILABLE_MANAGERSList of detected managers (when NEEDS_USER_CHOICE=true)
NEEDS_VERSION_CONFIRMtrue when no version specifier found
SUGGESTED_VERSIONLatest installed Ruby (when NEEDS_VERSION_CONFIRM=true)

Activation Commands by Manager

ManagerActivation CommandNotes
rbenveval "$(rbenv init -)"Or use rbenv exec ruby ...
chrubysource .../chruby.sh && chruby <version>detect.sh provides full command
rvmsource "$HOME/.rvm/scripts/rvm"Or use ~/.rvm/bin/rvm-auto-ruby
asdf (v0.16+)Noneasdf exec ruby ...
asdf (<v0.16)source "$HOME/.asdf/asdf.sh"Then asdf exec ruby ...
miseNonemise x -- ruby ...
rvNonerv ruby run -- ...
shadowenvNoneshadowenv exec -- ruby ...
noneNoneruby ... (uses PATH)

Commands Requiring Activation

CategoryCommands
Coreruby, irb, gem, bundle, bundler
Build/Taskrake, rails, thor
Testingrspec, minitest, cucumber
Lintingrubocop, standardrb, reek
LSP/IDEruby-lsp, solargraph, steep
Debugpry, byebug, debug
Gem binariesAny executable from gem install or Gemfile
Show full SKILL.md (176 more words)Show less

Handling Special Cases

Multiple Version Managers (NEEDS_USER_CHOICE=true)

Ask the user which manager to use, then store preference:

bash
/path/to/set-preference.sh chruby  # Saves to ~/.config/ruby-skills/preference.json

Detection priority: shadowenv > chruby > rbenv > rvm > asdf > rv > mise > none

No Version Specifier (NEEDS_VERSION_CONFIRM=true)

Ask: "No .ruby-version found. Use Ruby [SUGGESTED_VERSION] for this session?" If declined, show options from INSTALLED_RUBIES.

Version Not Installed (VERSION_AVAILABLE=false)

Inform user and offer installation:

Ruby {PROJECT_RUBY_VERSION} is not installed. Install with:

  • rbenv: rbenv install {VERSION}
  • rvm: rvm install {VERSION}
  • asdf: asdf install ruby {VERSION}
  • mise: mise install ruby@{VERSION}
  • chruby: ruby-install ruby {VERSION}

Always ask before installing. For chruby, check INSTALLED_RUBIES for compatible versions (same major.minor).

Shadowenv Trust Issues

If "untrusted shadowenv program" error appears, user must run shadowenv trust in the project directory.

Version Format Variations

Supported formats: 3.3.0, ruby-3.3.0, truffleruby-21.3.0, 3.3.0-rc1, 3.3 (matches any patch)

CI/Docker Environments

When VERSION_MANAGER=none, use system Ruby directly.

Troubleshooting

If Ruby commands fail after activation:

  1. Re-run detect.sh to verify environment
  2. Check VERSION_AVAILABLE - install if false
  3. Verify manager installation at VERSION_MANAGER_PATH
  4. chruby: Check ~/.rubies or /opt/rubies for installations
  5. rvm: Check both ~/.rvm and /usr/local/rvm

© st0012, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 4 other files in plugins/ruby-skills/skills/ruby-version-manager of st0012/ruby-skills.

  • SKILL.md
  • README.md
  • detect-all-managers.sh
  • detect.sh
  • set-preference.sh

Open the folder on GitHubat commit b1ea8b5

Compare with similar skills

Ruby Version Manager next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Ruby Version Manager compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Ruby Version Manager this skillst0012/ruby-skills125—~1.3kAutomated safety check: PassMIT
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Backfill Event Datarubyevents/rubyevents569—~2.8kAutomated safety check: PassNone
Upgrade RailsRailsEventStore/ecommerce507—~976Automated safety check: PassMIT
Rails ExpertJeffallan/claude-skills12k—~1.4kAutomated safety check: PassMIT
Production Log Inspectionbikeindex/bike_index308—~3.6kAutomated safety check: PassAGPL-3.0

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Works with

Categories

Questions about Ruby Version Manager

What does Ruby Version Manager do?

Use at session start for Ruby projects (Gemfile, .ruby-version, or .tool-versions present). Ruby Version Manager is an agent skill from st0012/ruby-skills.tool-versions present).

When should I use Ruby Version Manager?

Ruby Version Manager fits situations like: tasks that involve Backend development.

How do I install Ruby Version Manager in Claude Code?

Run `npx skills add st0012/ruby-skills --skill ruby-version-manager -a claude-code`. Or copy the skill folder (plugins/ruby-skills/skills/ruby-version-manager in st0012/ruby-skills) into .claude/skills/ruby-version-manager in your project. Claude Code loads it when a task matches its description.

How do I install Ruby Version Manager in Codex?

Run `npx skills add st0012/ruby-skills --skill ruby-version-manager -a codex`. Or copy the skill folder (plugins/ruby-skills/skills/ruby-version-manager in st0012/ruby-skills) into .agents/skills/ruby-version-manager in your project. Codex loads it when a task matches its description.

Can I use Ruby Version Manager in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add st0012/ruby-skills --skill ruby-version-manager -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/ruby-version-manager, .gemini/skills/ruby-version-manager, .github/skills/ruby-version-manager and .opencode/skills/ruby-version-manager in your project.

What does Ruby Version Manager need to run?

Going by SKILL.md and its folder, Ruby Version Manager needs a shell for the scripts in its folder and the command-line tools its instructions call (rbenv, asdf, bundle, mise, ruby and gem). Our summary lists: A Bash shell; Docker.

Does Ruby Version Manager access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Ruby Version Manager safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Ruby Version Manager use?

Ruby Version Manager is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Ruby Version Manager use?

About 1.3k tokens (SKILL.md is roughly 5.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Ruby Version Manager?

Skills that share tags, products or a category with Ruby Version Manager: Antipattern Prevention (doorkeeper-gem/doorkeeper, 5.5k stars), Backfill Event Data (rubyevents/rubyevents, 569 stars), Upgrade Rails (RailsEventStore/ecommerce, 507 stars) and Rails Expert (Jeffallan/claude-skills, 12k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Ruby Version Manager?

st0012 (a GitHub user) maintains it in st0012/ruby-skills, which has 125 GitHub stars. The repository holds 3 skills in this directory. The repository was last updated on June 13, 2026.

Source: st0012/ruby-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.