nodejs/doc/api/cli.md

Command Line Options

Node.js comes with a 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)

--openssl-config=file

Load an OpenSSL configuration file on startup. Among other uses, this can be used to enable FIPS-compliant crypto if Node.js is built with ./configure --openssl-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_PRESERVE_SYMLINKS=1

When set to 1, instructs the module loader to preserve symbolic links when resolving and caching modules.

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.

NODE_TTY_UNSAFE_ASYNC=1

When set to 1, writes to stdout and stderr will be non-blocking and asynchronous when outputting to a TTY on platforms which support async stdio. Setting this will void any guarantee that stdio will not be interleaved or dropped at program exit. Use of this mode is not recommended.