# Streams

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- **Type:** Skill
- **Install:** `agentstack add skill-posidoni-shell-skill-streams`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [posidoni](https://agentstack.voostack.com/s/posidoni)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [posidoni](https://github.com/posidoni)
- **Source:** https://github.com/posidoni/shell-skill/tree/main/skills/streams

## Install

```sh
agentstack add skill-posidoni-shell-skill-streams
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Streams

fd 0 is stdin, fd 1 is stdout (data), fd 2 is stderr (diagnostics). Depth and
citations in [`reference/streams.md`](../../reference/streams.md); runnable pairs
in [`examples/streams/`](../../examples/streams/).

## Rules at a glance

| Rule | Why | Code |
|------|-----|------|
| Diagnostics and prompts to stderr (`>&2`); data to stdout | keeps stdout pipeable and parseable | review-only |
| Signal failure with a non-zero exit, not just a message | callers test the exit status | — |
| Read lines with `while IFS= read -r line` | preserves whitespace and backslashes | — |
| Don't loop over `$(cat file)` | it word-splits and globs | `SC2013` |
| `cmd >file 2>&1`, not `cmd 2>&1 >file` | `2>&1` copies stdout's target at that moment | `SC2069` |
| Quote the delimiter (`<<'EOF'`) to stop expansion | literal here-doc | — |
| Never read and write the same file in one pipeline | the target is truncated first | — |
| `$(...)` strips trailing newlines | guard with a sentinel when they matter | — |

## Note

ShellCheck catches `SC2013` and `SC2069`, but **not** a diagnostic sent to stdout
instead of stderr — that one is enforced by review. A green lint does not mean
the streams are right.

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [posidoni](https://github.com/posidoni)
- **Source:** [posidoni/shell-skill](https://github.com/posidoni/shell-skill)
- **License:** MIT

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-posidoni-shell-skill-streams
- Seller: https://agentstack.voostack.com/s/posidoni
- Browse the marketplace: https://agentstack.voostack.com/browse

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Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.