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Ruby and rbenv Cheat Sheet

Essential Ruby and rbenv Commands

Check Installed Ruby Version

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ruby -v

Install Multiple Ruby Versions

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rbenv install 3.0.6
rbenv install 3.1.0

List Installed Versions

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rbenv versions

Set Global Ruby Version

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rbenv global <version>

Set Local Ruby Version (Per Directory)

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rbenv local <version>

Update Shims (Ensure Commands Use the Correct Ruby Version)

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rbenv rehash

Install a Gem System-Wide

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gem install <gem_name>

Troubleshooting Running WPScan with Ruby 3.0.6 and Metasploit with Ruby 3.1.0

Step 1: Set Global Ruby Version for WPScan

To ensure WPScan runs with Ruby 3.0.6, set it as the global version:

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rbenv global 3.0.6
rbenv rehash

Verify the active version:

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rbenv versions

Install WPScan:

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gem install wpscan

Step 2: Configure Ruby 3.1.0 for Metasploit

To ensure Metasploit uses Ruby 3.1.0, set a local Ruby version inside its directory:

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cd /usr/share/metasploit-framework
rbenv local 3.1.0
rbenv rehash

Running Metasploit from Any Directory

Alternative 1

By default, msfconsole -q will only work inside /usr/share/metasploit-framework. To run it from anywhere, use one of these approaches:

Approach 1: Specify the Version Inline
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RBENV_VERSION=3.1.0 msfconsole -q

Modify your .zshrc file:

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sudo nano ~/.zshrc

Add the following function at the bottom:

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# Wrapper for Metasploit to ensure it runs with Ruby 3.1.0
msfconsole() {
  echo "Launching Metasploit..."
  (cd /usr/share/metasploit-framework && exec /usr/share/metasploit-framework/msfconsole "$@")
}

Apply the changes:

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source ~/.zshrc

Now, both wpscan and msfconsole can be used from anywhere in the system with their respective Ruby versions.

Alternative 2

I finally went for this.

I'm using rbenv, with rbenv global set to system, and ruby version to 3.3.7.

Create the bash script ~/.local/bin/run_tool:

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#!/bin/bash

# Tool → Ruby version mapping
declare -A ruby_versions=(
  [wpscan]="3.0.6"
  [msfconsole]="system"
#  Adding a new tool:
# [msfvenom]="system"
)

tool="$1"
shift  # Remove the tool from the argument list

if [[ -z "$tool" ]]; then
  echo "Usage: ./run_tool.sh <tool> [args...]"
  exit 1
fi

if [[ ${ruby_versions[$tool]+_} ]]; then
  export RBENV_VERSION="${ruby_versions[$tool]}"
  echo "[*] Using Ruby version: $RBENV_VERSION for $tool"
else
  echo "[!] No Ruby version mapped for $tool — using current rbenv version."
fi

# Rehash to ensure shims are updated
eval "$(rbenv init -)" &>/dev/null
rbenv rehash

# Execute the tool
exec "$tool" "$@"

We need to be sure that ~/.local/bin/ is in the $PATH environmental variable.

Now in my ~/.zshr, I added these lines and, after that I sourced the file:

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alias wpscan='~/.local/bin/run_tool wpscan'
alias msfconsole='~/.local/bin/run_tool msfconsole'
Last update: 2025-04-13
Created: February 23, 2025 12:06:38