just-bash: Bash for Agents
Open-source TypeScript tool creates in-memory virtual filesystem with optional network access for AI agents
Just-bash is a new TypeScript-based simulated bash environment that provides AI agents with a secure, sandboxed shell execution environment featuring an in-memory virtual filesystem. Created as an open-source tool, it addresses the critical security challenge of allowing AI agents to execute bash commands without exposing host systems to risk. The environment supports optional network access through curl with secure-by-default URL filtering and offers Vercel Sandbox compatibility, making it particularly valuable for developers building agentic AI systems that require shell interaction.
The tool provides four filesystem implementations: InMemoryFs (default), OverlayFs for copy-on-write operations, ReadWriteFs for direct disk access, and MountableFs for complex setups. Each exec() call is isolated—environment variables, functions, and current working directory don't persist across calls, though the filesystem does. The system includes execution protection against infinite loops and supports custom TypeScript commands via defineCommand API. As beta software, it represents a significant step toward safer AI agent deployment by providing controlled bash access without requiring full VM isolation.
- TypeScript-based simulated bash environment with in-memory virtual filesystem for AI agent security
- Four filesystem implementations: InMemoryFs, OverlayFs, ReadWriteFs, and MountableFs with different access patterns
- Optional network access via curl with URL filtering and execution protection against infinite loops
Why It Matters
Enables safer deployment of AI agents that need shell access without compromising system security or requiring full VM isolation.