@bwilliamson/template-engine-cli

Command-line tool for rendering mergeEngine-style templates with JSON data.

Pre-1.0: Expect breaking changes in CLI flags and template syntax until 1.0.0. Pin exact versions and check release notes before upgrading.

Requires Node.js >= 22.12.

Install

npm install -g @bwilliamson/template-engine-cli

Usage

template-engine --template template.txt --data data.json
cat template.txt | template-engine --data data.json
template-engine --help

Options

| Flag | Required | Description | | ------------------- | -------- | -------------------------------------------- | | --data <file> | Yes | JSON file used as the template data context | | --template <file> | No | Template file; reads from stdin when omitted | | --help | No | Show usage |

Rendered output is written to stdout. Errors (including parse failures with source location) go to stderr.

Example

data.json

{ "name": "World" }

template.txt

Hello, <#name#>!

template-engine --template template.txt --data data.json
# Hello, World!

Template language

The CLI uses legacy syntax — the same language parsed by parseLegacy in @bwilliamson/template-engine-core.

| Construct | Syntax | Purpose | | ------------- | ------------------------- | ----------------------------------------- | | Variable | <#name#> | Insert a value from --data | | Loop | <~ ... <*> <[items]> ~> | Repeat for each array element | | Conditional | <~<+> ... <?cond?> ~> | Render one branch | | Function call | <{fn(...)}> | Not available in the CLI (empty registry) |

See the Template Language Reference for the complete guide.

Behavior notes

Stdin: The CLI reads the entire stdin stream before parsing. It does not wait for more input when a tag looks incomplete; if the stream closes mid-tag, parsing fails with a syntax error.

Functions: The CLI intentionally registers no template functions. For custom functions, use the core library in a host application.

Standalone executable

For environments without Node.js, build a single-file binary from the monorepo root:

pnpm --filter @bwilliamson/template-engine-cli run build:standalone:linux   # or :macos / :windows

Output lands in packages/template-engine-cli/dist/. See DEVELOPERS.md for release details.

Links

• Core library
• Repository
• Issues