- [Improved Windows support.](https://github.com/IndigoUnited/node-cross-spawn#why)
- Higher max buffer. 100 MB instead of 200 KB.
- [Executes locally installed binaries by name.](#preferlocal)
- [Cleans up spawned processes when the parent process dies.](#cleanup)
- [Get interleaved output](#all) from `stdout` and `stderr` similar to what is printed on the terminal. [*(Async only)*](#execasyncfile-arguments-options)
- [Can specify file and arguments as a single string without a shell](#execacommandcommand-options)
Using SIGTERM, and after 2 seconds, kill it with SIGKILL.
```js
const subprocess = execa('node');
setTimeout(() => {
subprocess.kill('SIGTERM', {
forceKillAfterTimeout: 2000
});
}, 1000);
```
## API
### execa(file, arguments, options?)
Execute a file. Think of this as a mix of [`child_process.execFile()`](https://nodejs.org/api/child_process.html#child_process_child_process_execfile_file_args_options_callback) and [`child_process.spawn()`](https://nodejs.org/api/child_process.html#child_process_child_process_spawn_command_args_options).
No escaping/quoting is needed.
Unless the [`shell`](#shell) option is used, no shell interpreter (Bash, `cmd.exe`, etc.) is used, so shell features such as variables substitution (`echo $PATH`) are not allowed.
Returns a [`child_process` instance](https://nodejs.org/api/child_process.html#child_process_class_childprocess) which:
- is also a `Promise` resolving or rejecting with a [`childProcessResult`](#childProcessResult).
- exposes the following additional methods and properties.
#### kill(signal?, options?)
Same as the original [`child_process#kill()`](https://nodejs.org/api/child_process.html#child_process_subprocess_kill_signal) except: if `signal` is `SIGTERM` (the default value) and the child process is not terminated after 5 seconds, force it by sending `SIGKILL`.
##### options.forceKillAfterTimeout
Type: `number | false`\
Default: `5000`
Milliseconds to wait for the child process to terminate before sending `SIGKILL`.
Can be disabled with `false`.
#### cancel()
Similar to [`childProcess.kill()`](https://nodejs.org/api/child_process.html#child_process_subprocess_kill_signal). This is preferred when cancelling the child process execution as the error is more descriptive and [`childProcessResult.isCanceled`](#iscanceled) is set to `true`.
#### all
Type: `ReadableStream | undefined`
Stream combining/interleaving [`stdout`](https://nodejs.org/api/child_process.html#child_process_subprocess_stdout) and [`stderr`](https://nodejs.org/api/child_process.html#child_process_subprocess_stderr).
This is `undefined` if either:
- the [`all` option](#all-2) is `false` (the default value)
- both [`stdout`](#stdout-1) and [`stderr`](#stderr-1) options are set to [`'inherit'`, `'ipc'`, `Stream` or `integer`](https://nodejs.org/dist/latest-v6.x/docs/api/child_process.html#child_process_options_stdio)
### execa.sync(file, arguments?, options?)
Execute a file synchronously.
Returns or throws a [`childProcessResult`](#childProcessResult).
### execa.command(command, options?)
Same as [`execa()`](#execafile-arguments-options) except both file and arguments are specified in a single `command` string. For example, `execa('echo', ['unicorns'])` is the same as `execa.command('echo unicorns')`.
If the file or an argument contains spaces, they must be escaped with backslashes. This matters especially if `command` is not a constant but a variable, for example with `__dirname` or `process.cwd()`. Except for spaces, no escaping/quoting is needed.
The [`shell` option](#shell) must be used if the `command` uses shell-specific features (for example, `&&` or `||`), as opposed to being a simple `file` followed by its `arguments`.
Same as [`execa.command()`](#execacommand-command-options) but synchronous.
Returns or throws a [`childProcessResult`](#childProcessResult).
### execa.node(scriptPath, arguments?, options?)
Execute a Node.js script as a child process.
Same as `execa('node', [scriptPath, ...arguments], options)` except (like [`child_process#fork()`](https://nodejs.org/api/child_process.html#child_process_child_process_fork_modulepath_args_options)):
- the current Node version and options are used. This can be overridden using the [`nodePath`](#nodepath-for-node-only) and [`nodeOptions`](#nodeoptions-for-node-only) options.
- the [`shell`](#shell) option cannot be used
- an extra channel [`ipc`](https://nodejs.org/api/child_process.html#child_process_options_stdio) is passed to [`stdio`](#stdio)
### childProcessResult
Type: `object`
Result of a child process execution. On success this is a plain object. On failure this is also an `Error` instance.
The child process [fails](#failed) when:
- its [exit code](#exitcode) is not `0`
- it was [killed](#killed) with a [signal](#signal)
- [timing out](#timedout)
- [being canceled](#iscanceled)
- there's not enough memory or there are already too many child processes
The file and arguments that were run, for logging purposes.
This is not escaped and should not be executed directly as a process, including using [`execa()`](#execafile-arguments-options) or [`execa.command()`](#execacommandcommand-options).
#### escapedCommand
Type: `string`
Same as [`command`](#command) but escaped.
This is meant to be copy and pasted into a shell, for debugging purposes.
Since the escaping is fairly basic, this should not be executed directly as a process, including using [`execa()`](#execafile-arguments-options) or [`execa.command()`](#execacommandcommand-options).
The numeric exit code of the process that was run.
#### stdout
Type: `string | Buffer`
The output of the process on stdout.
#### stderr
Type: `string | Buffer`
The output of the process on stderr.
#### all
Type: `string | Buffer | undefined`
The output of the process with `stdout` and `stderr` interleaved.
This is `undefined` if either:
- the [`all` option](#all-2) is `false` (the default value)
-`execa.sync()` was used
#### failed
Type: `boolean`
Whether the process failed to run.
#### timedOut
Type: `boolean`
Whether the process timed out.
#### isCanceled
Type: `boolean`
Whether the process was canceled.
#### killed
Type: `boolean`
Whether the process was killed.
#### signal
Type: `string | undefined`
The name of the signal that was used to terminate the process. For example, `SIGFPE`.
If a signal terminated the process, this property is defined and included in the error message. Otherwise it is `undefined`.
#### signalDescription
Type: `string | undefined`
A human-friendly description of the signal that was used to terminate the process. For example, `Floating point arithmetic error`.
If a signal terminated the process, this property is defined and included in the error message. Otherwise it is `undefined`. It is also `undefined` when the signal is very uncommon which should seldomly happen.
#### message
Type: `string`
Error message when the child process failed to run. In addition to the [underlying error message](#originalMessage), it also contains some information related to why the child process errored.
The child process [stderr](#stderr) then [stdout](#stdout) are appended to the end, separated with newlines and not interleaved.
#### shortMessage
Type: `string`
This is the same as the [`message` property](#message) except it does not include the child process stdout/stderr.
#### originalMessage
Type: `string | undefined`
Original error message. This is the same as the `message` property except it includes neither the child process stdout/stderr nor some additional information added by Execa.
This is `undefined` unless the child process exited due to an `error` event or a timeout.
### options
Type: `object`
#### cleanup
Type: `boolean`\
Default: `true`
Kill the spawned process when the parent process exits unless either:
- the spawned process is [`detached`](https://nodejs.org/api/child_process.html#child_process_options_detached)
- the parent process is terminated abruptly, for example, with `SIGKILL` as opposed to `SIGTERM` or a normal exit
#### preferLocal
Type: `boolean`\
Default: `false`
Prefer locally installed binaries when looking for a binary to execute.\
If you `$ npm install foo`, you can then `execa('foo')`.
#### localDir
Type: `string`\
Default: `process.cwd()`
Preferred path to find locally installed binaries in (use with `preferLocal`).
Path to the Node.js executable to use in child processes.
This can be either an absolute path or a path relative to the [`cwd` option](#cwd).
Requires [`preferLocal`](#preferlocal) to be `true`.
For example, this can be used together with [`get-node`](https://github.com/ehmicky/get-node) to run a specific Node.js version in a child process.
#### buffer
Type: `boolean`\
Default: `true`
Buffer the output from the spawned process. When set to `false`, you must read the output of [`stdout`](#stdout-1) and [`stderr`](#stderr-1) (or [`all`](#all) if the [`all`](#all-2) option is `true`). Otherwise the returned promise will not be resolved/rejected.
If the spawned process fails, [`error.stdout`](#stdout), [`error.stderr`](#stderr), and [`error.all`](#all) will contain the buffered data.
#### input
Type: `string | Buffer | stream.Readable`
Write some input to the `stdin` of your binary.\
Streams are not allowed when using the synchronous methods.
#### stdin
Type: `string | number | Stream | undefined`\
Default: `pipe`
Same options as [`stdio`](https://nodejs.org/dist/latest-v6.x/docs/api/child_process.html#child_process_options_stdio).
#### stdout
Type: `string | number | Stream | undefined`\
Default: `pipe`
Same options as [`stdio`](https://nodejs.org/dist/latest-v6.x/docs/api/child_process.html#child_process_options_stdio).
#### stderr
Type: `string | number | Stream | undefined`\
Default: `pipe`
Same options as [`stdio`](https://nodejs.org/dist/latest-v6.x/docs/api/child_process.html#child_process_options_stdio).
#### all
Type: `boolean`\
Default: `false`
Add an `.all` property on the [promise](#all) and the [resolved value](#all-1). The property contains the output of the process with `stdout` and `stderr` interleaved.
#### reject
Type: `boolean`\
Default: `true`
Setting this to `false` resolves the promise with the error instead of rejecting it.
#### stripFinalNewline
Type: `boolean`\
Default: `true`
Strip the final [newline character](https://en.wikipedia.org/wiki/Newline) from the output.
#### extendEnv
Type: `boolean`\
Default: `true`
Set to `false` if you don't want to extend the environment variables when providing the `env` property.
---
Execa also accepts the below options which are the same as the options for [`child_process#spawn()`](https://nodejs.org/api/child_process.html#child_process_child_process_spawn_command_args_options)/[`child_process#exec()`](https://nodejs.org/api/child_process.html#child_process_child_process_exec_command_options_callback)
#### cwd
Type: `string`\
Default: `process.cwd()`
Current working directory of the child process.
#### env
Type: `object`\
Default: `process.env`
Environment key-value pairs. Extends automatically from `process.env`. Set [`extendEnv`](#extendenv) to `false` if you don't want this.
#### argv0
Type: `string`
Explicitly set the value of `argv[0]` sent to the child process. This will be set to `file` if not specified.
Specify the kind of serialization used for sending messages between processes when using the [`stdio: 'ipc'`](#stdio) option or [`execa.node()`](#execanodescriptpath-arguments-options):
-`json`: Uses `JSON.stringify()` and `JSON.parse()`.
Prepare child to run independently of its parent process. Specific behavior [depends on the platform](https://nodejs.org/api/child_process.html#child_process_options_detached).
#### uid
Type: `number`
Sets the user identity of the process.
#### gid
Type: `number`
Sets the group identity of the process.
#### shell
Type: `boolean | string`\
Default: `false`
If `true`, runs `file` inside of a shell. Uses `/bin/sh` on UNIX and `cmd.exe` on Windows. A different shell can be specified as a string. The shell should understand the `-c` switch on UNIX or `/d /s /c` on Windows.
We recommend against using this option since it is:
- not cross-platform, encouraging shell-specific syntax.
- slower, because of the additional shell interpretation.
- unsafe, potentially allowing command injection.
#### encoding
Type: `string | null`\
Default: `utf8`
Specify the character encoding used to decode the `stdout` and `stderr` output. If set to `null`, then `stdout` and `stderr` will be a `Buffer` instead of a string.
#### timeout
Type: `number`\
Default: `0`
If timeout is greater than `0`, the parent will send the signal identified by the `killSignal` property (the default is `SIGTERM`) if the child runs longer than timeout milliseconds.
#### maxBuffer
Type: `number`\
Default: `100_000_000` (100 MB)
Largest amount of data in bytes allowed on `stdout` or `stderr`.
#### killSignal
Type: `string | number`\
Default: `SIGTERM`
Signal value to be used when the spawned process will be killed.
#### windowsVerbatimArguments
Type: `boolean`\
Default: `false`
If `true`, no quoting or escaping of arguments is done on Windows. Ignored on other platforms. This is set to `true` automatically when the `shell` option is `true`.
#### windowsHide
Type: `boolean`\
Default: `true`
On Windows, do not create a new console window. Please note this also prevents `CTRL-C` [from working](https://github.com/nodejs/node/issues/29837) on Windows.
`execa` can be combined with [`get-bin-path`](https://github.com/ehmicky/get-bin-path) to test the current package's binary. As opposed to hard-coding the path to the binary, this validates that the `package.json``bin` field is correctly set up.
## Related
- [gulp-execa](https://github.com/ehmicky/gulp-execa) - Gulp plugin for `execa`
- [nvexeca](https://github.com/ehmicky/nvexeca) - Run `execa` using any Node.js version
- [sudo-prompt](https://github.com/jorangreef/sudo-prompt) - Run commands with elevated privileges.
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