Documentation

Docs index

Reference material for operators, automation engineers, and agent developers. For the canonical source, see the docs/ tree on GitHub.

5250Script

Full reference for the scripting language — commands, control flow, functions, error handlers, and variable interpolation.

Themes

The 13 built-in themes and the JSON shape for authoring your own.

README

Installation instructions for Linux, macOS, and Windows, plus the complete command-line flag reference.

Command line

Starting 5250ng from the terminal

5250ng [options]

  -H, --host <hostname>          Host to connect to (auto-connects at startup)
  -p, --port <port>              Port number (default: 23)
      --tls                      Use TLS/SSL encryption
  -s, --load-session-from-name   Load a saved session by name
  -f, --load-session-from-file   Load a session from a JSON file
      --enable-mcp-server        Enable the MCP server on startup
      --mcp-server-port <port>   MCP server port (default: 9250)
  -d, --debug                    Enable debug output
  -h, --help                     Show help
  -v, --version                  Show version

Examples

# Auto-connect on startup
5250ng --host as400.example.com

# TLS on the standard port
5250ng --host as400.example.com --port 992 --tls

# Load a saved session profile
5250ng --load-session-from-name "Production AS400"

# Start with the MCP server enabled
5250ng --enable-mcp-server --mcp-server-port 9250

MCP integration

Using the Model Context Protocol server

When launched with --enable-mcp-server, 5250ng exposes a JSON-RPC 2.0 server over HTTP on the configured port (default 9250). Any MCP-capable client — Claude Desktop, IDE agents, custom tooling — can connect and invoke the session, screen, action, and filesystem tools documented on the home page.

Each MCP session is isolated by session ID, and a per-session busy guard prevents race conditions during script execution. File-system tools gate writes behind explicit user approval in the UI.