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Agent skill

Shell Python Fallback

by HKUDS in HKUDS/OpenSpace

Use runshell with embedded Python heredoc as reliable fallback when code execution tools fail

MITAuto-check passed

Install Shell Python Fallback

skills CLI
$ npx skills add HKUDS/OpenSpace --skill shell-python-fallback -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install HKUDS/OpenSpace shell-python-fallback --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/HKUDS/OpenSpace.git skills-src && mkdir -p .claude/skills && cp -r skills-src/benchmarks/gdpval/skills/shell-python-fallback .claude/skills/shell-python-fallback && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
shell-python-fallback
GitHub stars
7.7k
Token cost
~774 tokens
SKILL.md length
289 words
Files
2
Skills in repo
199
Repo updated
First seen
Licence
MIT

At a glance

Use runshell with embedded Python heredoc as reliable fallback when code execution tools fail

  • Works in 5 steps: Identify the failure: When… → Write your Python script: Prepare the… → Embed in run_shell: Use run_shell with a… → …
  • SKILL.md covers When to Use, The Pattern, Step-by-Step Instructions and Example: PDF Generation, plus 4 more sections
  • Calls python3

What it does

Shell Python Fallback is an agent skill from HKUDS/OpenSpace. Use runshell with embedded Python heredoc as reliable fallback when code execution tools fail

Its SKILL.md is about 770 tokens, which your agent loads only when the skill is triggered. The skill folder holds 1 other file.

It works with Python. The repository describes itself as: "OpenSpace: The Skill Management Layer for AI Agents" -- https://open-space.cloud/. The licence is MIT.

Example prompts

  • “/shell-python-fallback”

Requirements

  • Python 3

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

  1. Identify the failure: When execute_code_sandbox or shell_agent returns "unknown error" repeatedly (2+ attempts), switch to this fallback.
  2. Write your Python script: Prepare the complete Python code you need to execute.
  3. Embed in run_shell: Use run_shell with a heredoc syntax
  4. Handle multi-line scripts: For longer scripts, ensure proper indentation is preserved. The heredoc preserves whitespace exactly.
  5. Check output: Parse the stdout from run_shell to verify success or capture errors.

What it can do on your machine

Read from SKILL.md and the folder at commit 3827781. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • python3

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Shell Python Fallback loads about 774 tokens when it runs. Until then it costs about 29 tokens; SKILL.md has 289 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~29
When it runs · the whole SKILL.md, loaded when a task matches
~774

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from HKUDS/OpenSpace at commit 3827781, republished under its MIT licence (© HKUDS). 289 words, ~774 tokens.

Download SKILL.mdSave it as .claude/skills/shell-python-fallback/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
shell-python-fallback
description
Use run_shell with embedded Python heredoc as reliable fallback when code execution tools fail

Shell Python Fallback

When to Use

Use this pattern when execute_code_sandbox or shell_agent tools consistently fail with "unknown error" for tasks such as:

  • Data processing and transformation
  • PDF generation (reportlab, etc.)
  • File parsing and manipulation
  • Any Python script execution that requires reliability

The Pattern

Instead of using code execution tools, embed your Python script directly in a run_shell command using a heredoc:

bash
python3 << 'EOF'
# Your Python code here
import sys
print("Hello from embedded Python")
EOF

Step-by-Step Instructions

  1. Identify the failure: When execute_code_sandbox or shell_agent returns "unknown error" repeatedly (2+ attempts), switch to this fallback.

  2. Write your Python script: Prepare the complete Python code you need to execute.

  3. Embed in run_shell: Use run_shell with a heredoc syntax:

Command: python3 << 'EOF'
import json
# Your complete script here
data = {"key": "value"}
print(json.dumps(data))
EOF

  1. Handle multi-line scripts: For longer scripts, ensure proper indentation is preserved. The heredoc preserves whitespace exactly.

  2. Check output: Parse the stdout from run_shell to verify success or capture errors.

Example: PDF Generation

bash
python3 << 'EOF'
from reportlab.lib.pagesizes import letter
from reportlab.pdfgen import canvas

c = canvas.Canvas("output.pdf", pagesize=letter)
c.drawString(100, 750, "Hello World")
c.save()
print("PDF created successfully")
EOF

Example: Data Processing

bash
python3 << 'EOF'
import csv
import json

data = []
with open('input.csv', 'r') as f:
    reader = csv.DictReader(f)
    for row in reader:
        data.append(row)

with open('output.json', 'w') as f:
    json.dump(data, f, indent=2)

print(f"Processed {len(data)} records")
EOF

Best Practices

  • Quote the EOF delimiter (<< 'EOF' not << EOF) to prevent shell variable expansion in your Python code
  • Include error handling in your Python script with try/except blocks
  • Print status messages to stdout so you can verify execution succeeded
  • Use absolute paths or ensure working directory is correct
  • Test incrementally: Start with a minimal script, then expand

Troubleshooting

IssueSolution
Script doesn't runEnsure python3 is available in the shell environment
Indentation errorsCheck that heredoc preserves spaces (use spaces, not tabs)
Module not foundUse python3 -m pip install <module> before running script
File not foundUse absolute paths or pwd to verify working directory

Why This Works

The run_shell tool executes commands directly in the system shell, bypassing the sandbox restrictions or internal errors that affect execute_code_sandbox and shell_agent. The heredoc approach allows multi-line Python scripts while keeping everything in a single shell command.

© HKUDS, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file in benchmarks/gdpval/skills/shell-python-fallback of HKUDS/OpenSpace.

  • SKILL.md
  • .skill_id

Open the folder on GitHubat commit 3827781

Compare with similar skills

Shell Python Fallback next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Shell Python Fallback compared with similar skills
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Shell Python Fallback this skillHKUDS/OpenSpace7.7k—~774Automated safety check: PassMIT
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PDF Processinganthropics/skills180k48 repos~2kAutomated safety check: PassProprietary
NotebookLM Research AssistantPleasePrompto/notebooklm-skill7.8k13 repos~2.4kAutomated safety check: NotesMIT
Manim Video Productionbrowser-use/video-use28k6 repos~3kAutomated safety check: PassMIT
Code Review ChecklistshareAI-lab/learn-claude-code78k5 repos~1.1kAutomated safety check: PassMIT

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Works with

Questions about Shell Python Fallback

What does Shell Python Fallback do?

Use runshell with embedded Python heredoc as reliable fallback when code execution tools fail. Shell Python Fallback is an agent skill from HKUDS/OpenSpace.

How do I install Shell Python Fallback in Claude Code?

Run `npx skills add HKUDS/OpenSpace --skill shell-python-fallback -a claude-code`. Or copy the skill folder (benchmarks/gdpval/skills/shell-python-fallback in HKUDS/OpenSpace) into .claude/skills/shell-python-fallback in your project. Claude Code loads it when a task matches its description.

How do I install Shell Python Fallback in Codex?

Run `npx skills add HKUDS/OpenSpace --skill shell-python-fallback -a codex`. Or copy the skill folder (benchmarks/gdpval/skills/shell-python-fallback in HKUDS/OpenSpace) into .agents/skills/shell-python-fallback in your project. Codex loads it when a task matches its description.

Can I use Shell Python Fallback in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add HKUDS/OpenSpace --skill shell-python-fallback -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/shell-python-fallback, .gemini/skills/shell-python-fallback, .github/skills/shell-python-fallback and .opencode/skills/shell-python-fallback in your project.

What does Shell Python Fallback need to run?

Going by SKILL.md and its folder, Shell Python Fallback needs the command-line tools its instructions call (python3). Our summary lists: Python 3.

Does Shell Python Fallback access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Shell Python Fallback safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Shell Python Fallback use?

Shell Python Fallback is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Shell Python Fallback use?

About 774 tokens (SKILL.md is roughly 3.1k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Shell Python Fallback?

Skills that share tags, products or a category with Shell Python Fallback: MCP Server Builder (anthropics/skills, 180k stars), PDF Processing (anthropics/skills, 180k stars), NotebookLM Research Assistant (PleasePrompto/notebooklm-skill, 7.8k stars) and Manim Video Production (browser-use/video-use, 28k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Shell Python Fallback?

HKUDS (a GitHub organization) maintains it in HKUDS/OpenSpace, which has 7,743 GitHub stars. The repository holds 199 skills in this directory. The repository was last updated on August 12, 2026.

Source: HKUDS/OpenSpace on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.