explaingit

idank/explainshell

14,043PythonAudience · developerComplexity · 3/5Setup · moderate

TLDR

A Python web app that breaks apart any shell command and shows you what each flag and argument does, pulling the explanation directly from the relevant Linux manual page.

Mindmap

mindmap
  root((explainshell))
    What it does
      Parse shell commands
      Match flags to man pages
      Web UI display
    How it works
      bashlex syntax tree
      SQLite man page DB
      Flask web server
    Database building
      Prebuilt download
      Manual extraction
      LLM-assisted mode
    Audience
      Developers learning CLI
      Anyone reading scripts
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Code map

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Things people build with this

USE CASE 1

Paste a complex tar, grep, or curl command into the web UI and instantly see what every flag does without reading the full man page.

USE CASE 2

Run explainshell locally to explain shell commands using a prebuilt or self-built SQLite database of processed man pages.

USE CASE 3

Use the LLM-powered extraction mode to build a man page database that accurately identifies which text describes which option.

Tech stack

PythonFlaskSQLitebashlex

Getting it running

Difficulty · moderate Time to first run · 30min

Must download or build a SQLite man page database separately before any explanations work, the prebuilt version is available as a GitHub release.

License terms were not described in the explanation.

In plain English

explainshell is a Python-based web tool that takes a shell command and explains what each part of it does. If you paste in something like tar -xzvf archive.tar.gz, it breaks the command apart and shows you the relevant help text for each flag, pulled from the manual page for that command. The goal is to make terminal commands readable for someone who does not have every option memorized. The tool works by keeping a local database of processed Linux manual pages. Each manual page is analyzed to extract the list of options it documents and their descriptions. When you submit a command, explainshell parses it into a syntax tree using a library called bashlex, then walks through each node in that tree, matching commands and flags to stored descriptions. The results are rendered in a web interface built with Flask. Building the database is a separate offline step. You can either download a prebuilt copy or process man pages yourself using a command-line manager tool. The extractor supports two methods: parsing the raw formatting macros in the man page directly, or calling an LLM (such as a GPT model via the OpenAI API) that reads the page as markdown and identifies which line ranges correspond to which options. The LLM approach does not write new descriptions, it only picks out slices of the original text, so the explanations always come from the actual man page wording, not generated content. The SQLite database uses three tables: one for the raw compressed man page source, one for extracted options and metadata, and one that maps command names to the right man page entry. A single man page can have multiple mappings when it covers several subcommands or aliases. The live database for the public site is published as a GitHub release so you can download it without re-running extraction. You can run explainshell locally by cloning the repo, setting up a Python virtual environment, downloading the database, and starting the Flask server on port 5000. A test suite covers linting, unit tests, and end-to-end checks.

Copy-paste prompts

Prompt 1
I cloned explainshell and want to run it locally, walk me through downloading the prebuilt SQLite database and starting the Flask server on port 5000.
Prompt 2
How does explainshell parse a command like find . -name *.py -exec grep -l TODO ? Walk me through how it matches each token to a man page entry.
Prompt 3
I want to add a custom man page to the explainshell database, what command do I run to extract its options and insert them into the local SQLite DB?
Prompt 4
Explain the three SQLite tables explainshell uses and what each one stores, so I can query the database directly.
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