aromatt / cachenv

Memoize shell commands

cachenv

Versatile memoizing cache for program invocations, with a virtualenv-like interface.

Note: this repo is still in early development; the README is aspirational.

Overview

cachenv is a lightweight tool that provides caching for your commands, scripts, and pipelines. In fact, any program that calls exec() can use cachenv.

It's like function memoization, but at the process boundary. This is useful in a variety of contexts, especially testing and rapid iteration.

The workflow mirrors that of virtualenv - you create an environment, activate it, and work within it.

Use Cases

• Creating consistent, dependency-free testing environments
• Rapidly iterating on scripts or notebooks that rely on external services or data processing
• Efficiently constructing CLI pipelines that involve large inputs or expensive filters/aggregations
• Eliminating redundant calls to metered APIs

Usage

Initialize and activate a new cachenv:

$ cachenv init .cachenv
Created activate script at .cachenv/activate

$ source .cachenv/activate

Enable memoization for ls:

(.cachenv) $ cachenv add ls
Command 'ls' added to memoized commands.
Refreshed symlink for ls

Enjoy(?) memoization for ls:

(.cachenv) $ ls
foo

(.cachenv) $ touch bar
(.cachenv) $ ls
foo

Try diff mode:

(.cachenv) $ cachenv diff ls
0a1
> bar

Features

Implemented	Feature	Description
✅	Comprehensive Caching	Captures stdout, stderr, and exit codes, providing a complete snapshot of a program's behavior given a particular input.
	Selective Memoization	Supports precise configuration to selectively enable caching based on program name, arguments, and/or input patterns.
	Streaming Mode	Supports caching at the line level, keyed by stdin.
	File Awareness	Can optionally distinguish cache entries based on the contents of files provided as arguments (e.g., for grep foo bar.txt, refresh the cache when the content of bar.txt changes).
	Pipeline Compatibility	Naturally integrates with command pipelines, allowing a mix of cached and live executions within complex command chains. Also includes optimizations which can effectively cache entire pipelines.
✅	Diff Mode	Can show changes in a program's behavior against a cached snapshot.
✅	Cross-Environment Portability	Enables cache sharing and reuse across different machines and operating systems.