# Run a project's local tools

> Run the tools a project installed in node_modules/.bin by name, from any directory inside it, with runPath — npm-run-path's contract, without the dependency.

Source: https://bellpull.interlace.tools/docs/recipes/local-tools

`npm run` puts every `node_modules/.bin` from the working directory up in front of `PATH`, which
is why a script can say `lint` rather than `./node_modules/.bin/lint`. `runPath()` builds the
same `PATH`, so a program can run a project's tools the way its scripts do:

```js title="local.mjs"
import { chmodSync, mkdirSync, writeFileSync } from 'node:fs';
import { relative } from 'node:path';

import { run } from 'bellpull';
import { runPath } from 'bellpull/which';

import { runtimeWith } from './tools.mjs';

// A project with a locally installed tool, and a script one directory down.
mkdirSync('node_modules/.bin', { recursive: true });
writeFileSync('node_modules/.bin/lint', "#!/usr/bin/env node\nconsole.log('lint: 0 problems');\n");
chmodSync('node_modules/.bin/lint', 0o755);
mkdirSync('packages/app', { recursive: true });

const base = runtimeWith();
const runtime = { ...base, cwd: `${base.cwd}/packages/app` };
const local = { ...runtime, env: { ...runtime.env, PATH: runPath({ runtime }) } };

const result = await run('lint', [], { runtime: local });
console.log(result.stdout.trim());
console.log('from', relative(base.cwd, result.executable.from));
```

```text title="node local.mjs"
lint: 0 problems
from node_modules/.bin
```

The walk starts at the runtime's working directory, goes up one directory at a time, and stops
at the filesystem root — or the drive root on Windows, where the walk is in Windows dialect.
The nearest `node_modules/.bin` comes first, so a workspace package's own install wins over
the root's. `which.test.ts` checks all three.