110 lines
3.0 KiB
Markdown
110 lines
3.0 KiB
Markdown
# npm-which
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### Locate a program or locally installed node module executable
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[](https://travis-ci.org/timoxley/npm-which)
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Use `npm-which` to locate executables which may be installed in the
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local 'node_modules/.bin', or in a parent 'node_modules/.bin' directory.
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`npm-which` runs in the context of an npm lifecycle script with its npm-modified PATH.
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i.e. if you install a module that has an executable script using npm install, that module's executable will be picked up by `npm-which` from anywhere in the ./node_modules tree.
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## Installation
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```bash
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> npm install -g npm-which
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```
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## Usage
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### Programmatic
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`npm-which` will find executables relative to the cwd you supply.
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The cwd is required in order to be explicit and reduce confusion when
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things that should be found are not.
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#### Asynchronous
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```js
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var which = require('npm-which')(process.cwd()) // remember to supply cwd
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which('tape', function(err, pathToTape) {
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if (err) return console.error(err.message)
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console.log(pathToTape) // /Users/.../node_modules/.bin/tape
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})
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```
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#### Synchronous
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```js
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var which = require('npm-which')(__dirname) // __dirname often good enough
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var pathToTape = which.sync('tape')
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console.log(pathToTape) // /Users/.../node_modules/.bin/tape
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```
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#### Options
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Both async and sync versions take an optional options object:
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* Set `options.env` if you wish to use something other than `process.env` (the default)
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* Set `options.cwd` to supply the cwd as a named argument. Mainly for semi-backwards compatibility with npm-which 1.0.0.
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```js
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which('tape', {cwd: '/some/other/path'}, function() {
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// ...
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})
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```
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### Command Line
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```bash
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> npm-which tape
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/Users/timoxley/Projects/npm-which/node_modules/.bin/tape
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```
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This is the equivalent of running an npm script with the body: `which tape`.
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### Example
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```bash
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# unless something is installed in a node_modules
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# npm-which and which(1) will have the same output:
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> which tape
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/usr/local/bin/tape
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> npm-which tape
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/usr/local/bin/tape
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# install tape local to current dir
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# tape includes an executable 'tape'
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> npm install tape
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> ./node_modules/.bin/tape && echo 'found'
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found
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# vanilla which(1) still finds global tape
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> which tape
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/usr/local/bin/tape
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# npm-which finds locally installed tape :)
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> npm-which tape
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/Users/timoxley/Projects/npm-which/node_modules/.bin/tape
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```
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## Why
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#### npm is slow to boot
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* Shelling out to `npm bin` is very slow; it has to wait for all of npm to boot up – this often takes longer than the actual script you want to execute!
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#### Hard-coding paths to modules is very fragile
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* You can't rely on './node_modules' actually containing your module! The module may exist much higher in the directory hierarchy.
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* `npm bin` returns the location of the `./node_modules/.bin` directory, but it does not take into account being called within the context of another module, also, npm slow.
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* If the module does exist in a parent directory, then './node_modules/.bin' will be missing your module's executable.
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## License
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MIT
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