ruby — Ruby interpreter

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The interpreter that runs Ruby scripts.

Basic Information

What is this command?

ruby interprets scripts line by line. With no compile step you can iterate quickly, and -e runs a single line while -c only checks syntax.

Libraries are gems, with Bundler pinning per-project versions. Using rbenv or rvm instead of extending the system Ruby reduces conflicts during upgrades.

What problems does it solve?

• Running small automation scripts
• Starting Ruby applications such as Rails
• Checking syntax without executing
• Isolating Ruby versions per project

Key features

Running scripts

Pass a file to execute it.

• When to use: Running batch jobs or tooling scripts
• What you get: You see results immediately.
• Limitations: An exception aborts the run with a stack trace.

One-liners

The -e option runs a short snippet directly.

• When to use: Quick string processing or calculations
• What you get: No file needs to be created.
• Limitations: Quoting conflicts with the shell require care.

Syntax check

The -c option checks syntax without running.

• When to use: Validating edited scripts before deployment
• What you get: Finds errors without side effects.
• Limitations: It cannot catch runtime errors.

Installation and usage

Check whether it is installed

ruby --version

sudo apt install ruby-full # Debian/Ubuntu sudo dnf install ruby # Fedora

Real-world examples

Run a script

Execute a file.

ruby script.rb

Run a one-liner

Run a short snippet immediately.

ruby -e 'puts [1,2,3].sum'

Syntax check

Check syntax without executing.

ruby -c script.rb