feat(bin): two bins (shell, non-shell) (#104)

Revert the default bin (cross-env) to its v3 behavior (not using the shell option). Add a new
(cross-env-shell)  which uses the shell option.

BREAKING CHANGE: Scripts using quotes or escape sequences will see a difference in behavior.
Switching to the second bin should resolve any issue.

Closes #99.

README.md

@@ -58,7 +58,8 @@ I use this in my npm scripts:
 }
 ```
 
-Ultimately, the command that is executed (using `cross-spawn`) is:
+Ultimately, the command that is executed (using [`cross-spawn`][cross-spawn])
+is:
 
 ```
 webpack --config build/webpack.config.js
@@ -84,19 +85,32 @@ the parent. This is quite useful for launching the same command with different
 env variables or when the environment variables are too long to have everything
 in one line.
 
-## Gotchas
+## `cross-env` vs `cross-env-shell`
 
-If you want to have the environment variable apply to several commands in series
-then you will need to wrap those in quotes in your script. For example:
+The `cross-env` module exposes two bins: `cross-env` and `cross-env-shell`. The
+first one executes commands using [`cross-spawn`][cross-spawn], while the
+second one uses the `shell` option from Node's `spawn`.
+
+The main use case for `cross-env-shell` is when your need an environment
+variable to be set across an entire inline shell script, rather than just one
+command.
+
+For example, if you want to have the environment variable apply to several
+commands in series then you will need to wrap those in quotes and use 
+`cross-env-shell` instead of `cross-env`.
 
 ```json
 {
   "scripts": {
-    "greet": "cross-env GREETING=Hi NAME=Joe \"echo $GREETING && echo $NAME\""
+    "greet": "cross-env-shell GREETING=Hi NAME=Joe \"echo $GREETING && echo $NAME\""
   }
 }
 ```
 
+The rule of thumb is: if you want to pass to `cross-env` a command that
+contains special shell characters *that you want interpreted*, then use
+`cross-env-shell`. Otherwise stick to `cross-env`.
+
 ## Inspiration
 
 I originally created this to solve a problem I was having with my npm scripts in
@@ -164,3 +178,4 @@ MIT
 [all-contributors]: https://github.com/kentcdodds/all-contributors
 [win-bash]: https://msdn.microsoft.com/en-us/commandline/wsl/about
 [angular-formly]: https://github.com/formly-js/angular-formly
+[cross-spawn]: https://www.npmjs.com/package/cross-spawn

src/bin/cross-env-shell.js

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+
+const crossEnv = require('..')
+
+crossEnv(process.argv.slice(2), {shell: true})

src/index.js

@@ -6,15 +6,15 @@ module.exports = crossEnv
 
 const envSetterRegex = /(\w+)=('(.+)'|"(.+)"|(.+))/
 
-function crossEnv(args) {
+function crossEnv(args, options = {}) {
   const [envSetters, command, commandArgs] = parseCommand(args)
   if (command) {
     const proc = spawn(
       commandConvert(command),
       commandArgs.map(commandConvert),
       {
         stdio: 'inherit',
-        shell: true,
+        shell: options.shell,
         env: getEnvVars(envSetters),
       },
     )

src/index.test.js

@@ -44,7 +44,9 @@ it(`should handle equality signs in quoted strings`, () => {
 })
 
 it(`should handle quoted scripts`, () => {
-  crossEnv(['GREETING=Hi', 'NAME=Joe', 'echo $GREETING && echo $NAME'])
+  crossEnv(['GREETING=Hi', 'NAME=Joe', 'echo $GREETING && echo $NAME'], {
+    shell: true,
+  })
   expect(
     crossSpawnMock.spawn,
   ).toHaveBeenCalledWith('echo $GREETING && echo $NAME', [], {
@@ -94,7 +96,7 @@ function testEnvSetting(expected, ...envSettings) {
   expect(crossSpawnMock.spawn).toHaveBeenCalledTimes(1)
   expect(crossSpawnMock.spawn).toHaveBeenCalledWith('echo', ['hello world'], {
     stdio: 'inherit',
-    shell: true,
+    shell: undefined,
     env: Object.assign({}, process.env, env),
   })