Command Line Options Node.js v6.2.0 Manual & Documentation

Node.js

- About these Docs
- Usage & Example

- Assertion Testing
- Buffer
- C/C++ Addons
- Child Processes
- Cluster
- Command Line Options
- Console
- Crypto
- Debugger
- DNS
- Domain
- Errors
- Events
- File System
- Globals
- HTTP
- HTTPS
- Modules
- Net
- OS
- Path
- Process
- Punycode
- Query Strings
- Readline
- REPL
- Stream
- String Decoder
- Timers
- TLS/SSL
- TTY
- UDP/Datagram
- URL
- Utilities
- V8
- VM
- ZLIB

- GitHub Repo & Issue Tracker
- Mailing List

# Command Line Options#

Node.js comes with a wide variety of CLI options. These options expose built-in debugging, multiple ways to execute scripts, and other helpful runtime options.

To view this documentation as a manual page in your terminal, run `man node`.

## Synopsis#

`node [options] [v8 options] [script.js | -e "script"] [arguments]`

`node debug [script.js | -e "script" | <host>:<port>] …`

`node --v8-options`

Execute without arguments to start the REPL.

For more info about `node debug`, please see the debugger documentation.

## Options#

### `-v`, `--version`#

Print node's version.

### `-h`, `--help`#

Print node command line options. The output of this option is less detailed than this document.

### `-e`, `--eval "script"`#

Evaluate the following argument as JavaScript. The modules which are predefined in the REPL can also be used in `script`.

### `-p`, `--print "script"`#

Identical to `-e` but prints the result.

### `-c`, `--check`#

Syntax check the script without executing.

### `-i`, `--interactive`#

Opens the REPL even if stdin does not appear to be a terminal.

### `-r`, `--require module`#

Preload the specified module at startup.

Follows `require()`'s module resolution rules. `module` may be either a path to a file, or a node module name.

### `--no-deprecation`#

Silence deprecation warnings.

### `--trace-deprecation`#

Print stack traces for deprecations.

### `--throw-deprecation`#

Throw errors for deprecations.

### `--no-warnings`#

Silence all process warnings (including deprecations).

### `--trace-warnings`#

Print stack traces for process warnings (including deprecations).

### `--trace-sync-io`#

Prints a stack trace whenever synchronous I/O is detected after the first turn of the event loop.

### `--zero-fill-buffers`#

Automatically zero-fills all newly allocated Buffer and SlowBuffer instances.

### `--preserve-symlinks`#

Instructs the module loader to preserve symbolic links when resolving and caching modules.

By default, when Node.js loads a module from a path that is symbolically linked to a different on-disk location, Node.js will dereference the link and use the actual on-disk "real path" of the module as both an identifier and as a root path to locate other dependency modules. In most cases, this default behavior is acceptable. However, when using symbolically linked peer dependencies, as illustrated in the example below, the default behavior causes an exception to be thrown if `moduleA` attempts to require `moduleB` as a peer dependency:

    {appDir}
     ├── app
     │   ├── index.js
     │   └── node_modules
     │       ├── moduleA -> {appDir}/moduleA
     │       └── moduleB
     │           ├── index.js
     │           └── package.json
     └── moduleA
         ├── index.js
         └── package.json

The `--preserve-symlinks` command line flag instructs Node.js to use the symlink path for modules as opposed to the real path, allowing symbolically linked peer dependencies to be found.

Note, however, that using `--preserve-symlinks` can have other side effects. Specifically, symbolically linked native modules can fail to load if those are linked from more than one location in the dependency tree (Node.js would see those as two separate modules and would attempt to load the module multiple times, causing an exception to be thrown).

### `--track-heap-objects`#

Track heap object allocations for heap snapshots.

### `--prof-process`#

Process v8 profiler output generated using the v8 option `--prof`.

### `--v8-options`#

Print v8 command line options.

Note: v8 options allow words to be separated by both dashes (`-`) or underscores (`_`).

For example, `--stack-trace-limit` is equivalent to `--stack_trace_limit`.

### `--tls-cipher-list=list`#

Specify an alternative default TLS cipher list. (Requires Node.js to be built with crypto support. (Default))

### `--enable-fips`#

Enable FIPS-compliant crypto at startup. (Requires Node.js to be built with `./configure --openssl-fips`)

### `--force-fips`#

Force FIPS-compliant crypto on startup. (Cannot be disabled from script code.) (Same requirements as `--enable-fips`)

### `--icu-data-dir=file`#

Specify ICU data load path. (overrides `NODE_ICU_DATA`)

## Environment Variables#

### `NODE_DEBUG=module[,…]`#

`','`-separated list of core modules that should print debug information.

### `NODE_PATH=path[:…]`#

`':'`-separated list of directories prefixed to the module search path.

Note: on Windows, this is a `';'`-separated list instead.

### `NODE_DISABLE_COLORS=1`#

When set to `1` colors will not be used in the REPL.

### `NODE_ICU_DATA=file`#

Data path for ICU (Intl object) data. Will extend linked-in data when compiled with small-icu support.

### `NODE_REPL_HISTORY=file`#

Path to the file used to store the persistent REPL history. The default path is `~/.node_repl_history`, which is overridden by this variable. Setting the value to an empty string (`""` or `" "`) disables persistent REPL history.