ports

ports is a skill for Claude Code from vinnie357/claude-skills. It costs 48 tokens per session (3,948 once invoked), scanned C, original, MIT.

A guide to Elixir and Erlang Ports, which let an Elixir program communicate with an external operating-system process through standard input and output.

In plain words
What is it for?
Use it when starting external programs from Elixir, building a process wrapper, defining a communication protocol, or comparing Ports with other integration methods.
Why use it?
It explains how to choose and use this connection safely, including how to send data, receive responses, and close the process.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the elixir plugin — 9 skills, 1 agent shipped together

Good fit Use it when starting external programs from Elixir, building a process wrapper, defining a communication protocol, or comparing Ports with other integration methods.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/vinnie357/claude-skills/ports
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add vinnie357/claude-skills --skill ports
Clone the repo
git clone --depth 1 https://github.com/vinnie357/claude-skills

Made for: Claude Code.

Or install elixir, the plugin that ships this one along with the rest of its 9 skills, 1 agent.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for ports

README.md
[![agentmods](https://agentmods.dev/badge/skills/vinnie357/claude-skills/ports/github.svg)](https://agentmods.dev/skills/vinnie357/claude-skills/ports)
Your own site
<a href="https://agentmods.dev/skills/vinnie357/claude-skills/ports"><img src="https://agentmods.dev/badge/skills/vinnie357/claude-skills/ports/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for ports

Your own site · 80×15
<a href="https://agentmods.dev/skills/vinnie357/claude-skills/ports"><img src="https://agentmods.dev/badge/skills/vinnie357/claude-skills/ports.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,948 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00048 $0.03948
Opus 5 $0.00024 $0.01974
Sonnet 5 $0.00010 $0.00790
Haiku 4.5 $0.00005 $0.00395

Measured 11d ago against content hash 5cb6fdca97c8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade C, and why

ports scanned grade C with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Recursive force deletehighDestructive command

rm -rf with a variable or a broad path is one typo away from removing the wrong tree.

user_input = "file.txt; rm -rf /"
plugins/languages/elixir/skills/ports/SKILL.md · 432 lines

How it starts

The opening of the file, as written. The whole thing — 432 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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.

Port Fundamentals

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

# Spawn by shell command string (uses shell, PATH lookups apply)
port = Port.open({:spawn, "cat"}, [:binary])

# Spawn executable directly (no shell, preferred for security)
port = Port.open({:spawn_executable, "/usr/bin/python3"}, [
  :binary,
  args: ["-u", "my_script.py"]
])

Send data to the port and receive from it:

# Send bytes to the external process's stdin
Port.command(port, "hello\n")

# Receive response — messages arrive in the process mailbox
receive do
  {^port, {:data, data}} ->
    IO.puts("Got: #{data}")
end

Close the port explicitly or let it close when the owner process exits:

Port.close(port)
# The port will reply {port, :closed} after the external process exits

Port Options Reference

Option Description
:binary Deliver data as binaries (recommended; default is charlists)
{:packet, N} Prefix each message with N-byte length header (N = 1, 2, or 4)
{:line, L} Deliver complete lines up to L bytes; partial lines flagged
:stream No framing — raw bytes delivered as received (default)
:exit_status Send {port, {:exit_status, code}} when the program exits
:use_stdio Use stdin/stdout for communication (default)
:stderr_to_stdout Merge stderr into stdout stream
{:cd, dir} Set working directory for the external process
{:env, env_list} EXTENDS the spawned process's environment (does NOT replace it)
{:args, arg_list} Argument list when using :spawn_executable
{:arg0, string} Override argv[0] for the external process
:parallelism Hint to scheduler for improved throughput

Read the full file on GitHub · 432 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 11d ago First seen · 432 lines · 48 tokens per session scan C 5cb6fdca97c8

Subscribe to this mod's changes

ports is a skill published in the GitHub repository vinnie357/claude-skills (25 stars, last pushed yesterday), licensed MIT. It adds 48 tokens to every session and 3,948 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it C with 1 finding (recursive force delete). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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