Elixir Ports

Ports are Elixir's mechanism for communicating with external OS programs via stdin/stdout. A Port is not a network port — it is a process-like entity that manages an external OS program, forwarding messages as bytes and delivering responses back to the owning Elixir process.

When to Use This Skill

Activate when:

• Spawning and communicating with external programs or scripts
• Implementing binary protocols over stdin/stdout
• Wrapping a port in a GenServer for lifecycle management
• Deciding between Port, NIF, C Node, or System.cmd
• Handling port crashes, exit status, or monitoring ports
• Working with long-running external processes

Port Fundamentals

Open a port with Port.open/2. The most common name forms are {:spawn, command} and {:spawn_executable, path}.