nodejs1

Usage

Overview

Node.js is a set of libraries for JavaScript which allows it to be used outside of the browser. It is primarily focused on creating simple, easy-to-build network clients and servers.

Execute node without arguments to start a REPL.

Options

-

Alias for stdin, analogous to the use of - in other command-line utilities. The executed script is read from stdin, and remaining arguments are passed to the script.

--

Indicate the end of command-line options. Pass the rest of the arguments to the script.

If no script filename or eval/print script is supplied prior to this, then the next argument will be used as a script filename.

--abort-on-uncaught-exception

Aborting instead of exiting causes a core file to be generated for analysis.

--allow-fs-read

Allow file system read access when using the permission model.

--allow-fs-write

Allow file system write access when using the permission model.

--allow-addons

Allow using native addons when using the permission model.

--allow-child-process

Allow spawning process when using the permission model.

--allow-wasi

Allow execution of WASI when using the permission model.

--allow-worker

Allow creating worker threads when using the permission model.

--completion-bash

Print source-able bash completion script for Node.js.

-C, --conditions string

Use custom conditional exports conditions. string

--cpu-prof

Start the V8 CPU profiler on start up, and write the CPU profile to disk before exit. If --cpu-prof-dir is not specified, the profile will be written to the current working directory with a generated file name.

--cpu-prof-dir

The directory where the CPU profiles generated by --cpu-prof will be placed. The default value is controlled by the --diagnostic-dir. command-line option.

--cpu-prof-interval

The sampling interval in microseconds for the CPU profiles generated by --cpu-prof. The default is 1000.

--cpu-prof-name

File name of the V8 CPU profile generated with --cpu-prof.

--diagnostic-dir

Set the directory for all diagnostic output files. Default is current working directory. Set the directory to which all diagnostic output files will be written to. Defaults to current working directory. Affects the default output directory of: --cpu-prof-dir. --heap-prof-dir. --redirect-warnings.

--disable-proto=mode

Disable the `Object.prototype.__proto__` property. If mode is `delete`, the property will be removed entirely. If mode is `throw`, accesses to the property will throw an exception with the code `ERR_PROTO_ACCESS`.

--disable-wasm-trap-handler=mode

Disable trap-handler-based WebAssembly bound checks and fall back to inline bound checks so that WebAssembly can be run with limited virtual memory.

--disallow-code-generation-from-strings

Make built-in language features like `eval` and `new Function` that generate code from strings throw an exception instead. This does not affect the Node.js `vm` module.

--enable-fips

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

--enable-source-maps

Enable Source Map V3 support for stack traces.

--experimental-default-type=type

Interpret as either ES modules or CommonJS modules input via --eval or STDIN, when --input-type is unspecified;

--experimental-import-meta-resolve

Enable experimental ES modules support for import.meta.resolve().

--experimental-loader=module

Specify the module to use as a custom module loader.

--experimental-network-imports

Enable experimental support for loading modules using `import` over `https:`.

--experimental-permission

Enable the experimental permission model.

--experimental-policy

Use the specified file as a security policy.

--experimental-shadow-realm

Use this flag to enable ShadowRealm support.

--experimental-test-coverage

Enable code coverage in the test runner.

--experimental-test-module-mocks

Enable module mocking in the test runner.

--experimental-eventsource

Enable experimental support for the EventSource Web API.

--experimental-websocket

Enable experimental support for the WebSocket API.

--no-experimental-fetch

Disable experimental support for the Fetch API.

--no-experimental-global-customevent

Disable exposition of the CustomEvent on the global scope.

--no-experimental-global-webcrypto

Disable exposition of the Web Crypto API on the global scope.

--no-experimental-repl-await

Disable top-level await keyword support in REPL.

--experimental-vm-modules

Enable experimental ES module support in VM module.

--experimental-wasi-unstable-preview1

Enable experimental WebAssembly System Interface support. This flag is no longer required as WASI is enabled by default.

--experimental-wasm-modules

Enable experimental WebAssembly module support.

--force-context-aware

Disable loading native addons that are not context-aware.

--force-fips

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

--frozen-intrinsics

Enable experimental frozen intrinsics support.

--heapsnapshot-near-heap-limit=max_count

Generate heap snapshot when the V8 heap usage is approaching the heap limit. No more than the specified number of snapshots will be generated.

--heapsnapshot-signal=signal

Generate heap snapshot on specified signal.

--heap-prof

Start the V8 heap profiler on start up, and write the heap profile to disk before exit. If --heap-prof-dir is not specified, the profile will be written to the current working directory with a generated file name.

--heap-prof-dir

The directory where the heap profiles generated by --heap-prof will be placed. The default value is controlled by the --diagnostic-dir. command-line option.

--heap-prof-interval

The average sampling interval in bytes for the heap profiles generated by --heap-prof. The default is 512 * 1024.

--heap-prof-name

File name of the V8 heap profile generated with --heap-prof.

--icu-data-dir=file

Specify ICU data load path. Overrides NODE_ICU_DATA.

--input-type=type

Set the module resolution type for input via --eval, --print or STDIN.

--inspect-brk=[host:]port

Activate inspector on host:port and break at start of user script.

--inspect-port=[host:]port

Set the host:port to be used when the inspector is activated.

--inspect-publish-uid=stderr,http

Specify how the inspector WebSocket URL is exposed. Valid values are stderr and http. Default is stderr,http.

--inspect-wait=[host:]port

Activate inspector on host:port and wait for debugger to be attached.

--inspect=[host:]port

Activate inspector on host:port. Default is 127.0.0.1:9229.

V8 Inspector integration allows attaching Chrome DevTools and IDEs to Node.js instances for debugging and profiling. It uses the Chrome DevTools Protocol.

--insecure-http-parser

Use an insecure HTTP parser that accepts invalid HTTP headers. This may allow interoperability with non-conformant HTTP implementations. It may also allow request smuggling and other HTTP attacks that rely on invalid headers being accepted. Avoid using this option.

--jitless

Disable runtime allocation of executable memory. This may be required on some platforms for security reasons. It can also reduce attack surface on other platforms, but the performance impact may be severe.

This flag is inherited from V8 and is subject to change upstream. It may disappear in a non-semver-major release.

--max-http-header-size=size

Specify the maximum size of HTTP headers in bytes. Defaults to 16 KiB.

--napi-modules

This option is a no-op. It is kept for compatibility.

--no-deprecation

Silence deprecation warnings.

--no-extra-info-on-fatal-exception

Hide extra information on fatal exception that causes exit.

--no-force-async-hooks-checks

Disable runtime checks for `async_hooks`. These will still be enabled dynamically when `async_hooks` is enabled.

--no-addons

Disable the `node-addons` exports condition as well as disable loading native addons. When `--no-addons` is specified, calling `process.dlopen` or requiring a native C++ addon will fail and throw an exception.

--no-global-search-paths

Do not search modules from global paths.

--no-warnings

Silence all process warnings (including deprecations).

--node-memory-debug

Enable extra debug checks for memory leaks in Node.js internals. This is usually only useful for developers debugging Node.js itself.

--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.

--pending-deprecation

Emit pending deprecation warnings.

--policy-integrity=sri

Instructs Node.js to error prior to running any code if the policy does not have the specified integrity. It expects a Subresource Integrity string as a parameter.

--preserve-symlinks

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

--preserve-symlinks-main

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

--prof

Generate V8 profiler output.

--prof-process

Process V8 profiler output generated using the V8 option --prof.

--redirect-warnings=file

Write process warnings to the given file instead of printing to stderr.

--report-compact

Write diagnostic reports in a compact format, single-line JSON.

--report-dir --report-directory

Location at which the diagnostic report will be generated. The `file` name may be an absolute path. If it is not, the default directory it will be written to is controlled by the --diagnostic-dir. command-line option.

--report-filename

Name of the file to which the diagnostic report will be written.

--report-on-fatalerror

Enables the diagnostic report to be triggered on fatal errors (internal errors within the Node.js runtime such as out of memory) that leads to termination of the application. Useful to inspect various diagnostic data elements such as heap, stack, event loop state, resource consumption etc. to reason about the fatal error.

--report-on-signal

Enables diagnostic report to be generated upon receiving the specified (or predefined) signal to the running Node.js process. Default signal is SIGUSR2.

--report-signal

Sets or resets the signal for diagnostic report generation (not supported on Windows). Default signal is SIGUSR2.

--report-uncaught-exception

Enables diagnostic report to be generated on un-caught exceptions. Useful when inspecting JavaScript stack in conjunction with native stack and other runtime environment data.

--secure-heap=n

Specify the size of the OpenSSL secure heap. Any value less than 2 disables the secure heap. The default is 0. The value must be a power of two.

--secure-heap-min=n

Specify the minimum allocation from the OpenSSL secure heap. The default is 2. The value must be a power of two.

--test

Starts the Node.js command line test runner.

--test-concurrency

The maximum number of test files that the test runner CLI will execute concurrently.

--test-force-exit

Configures the test runner to exit the process once all known tests have finished executing even if the event loop would otherwise remain active.

--test-name-pattern

A regular expression that configures the test runner to only execute tests whose name matches the provided pattern.

--test-reporter

A test reporter to use when running tests.

--test-reporter-destination

The destination for the corresponding test reporter.

--test-only

Configures the test runner to only execute top level tests that have the `only` option set.

--test-shard

Test suite shard to execute in a format of <index>/<total>.

--test-timeout

A number of milliseconds the test execution will fail after.

--throw-deprecation

Throw errors for deprecations.

--title=title

Specify process.title on startup.

--tls-cipher-list=list

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

--tls-keylog=file

Log TLS key material to a file. The key material is in NSS SSLKEYLOGFILE format and can be used by software (such as Wireshark) to decrypt the TLS traffic.

--tls-max-v1.2

Set default maxVersion to 'TLSv1.2'. Use to disable support for TLSv1.3.

--tls-max-v1.3

Set default maxVersion to 'TLSv1.3'. Use to enable support for TLSv1.3.

--tls-min-v1.0

Set default minVersion to 'TLSv1'. Use for compatibility with old TLS clients or servers.

--tls-min-v1.1

Set default minVersion to 'TLSv1.1'. Use for compatibility with old TLS clients or servers.

--tls-min-v1.2

Set default minVersion to 'TLSv1.2'. This is the default for 12.x and later, but the option is supported for compatibility with older Node.js versions.

--tls-min-v1.3

Set default minVersion to 'TLSv1.3'. Use to disable support for TLSv1.2 in favour of TLSv1.3, which is more secure.

--trace-atomics-wait

Print short summaries of calls to Atomics.wait(). This flag is deprecated.

--trace-deprecation

Print stack traces for deprecations.

--trace-event-categories categories

A comma-separated list of categories that should be traced when trace event tracing is enabled using --trace-events-enabled.

--trace-event-file-pattern pattern

Template string specifying the filepath for the trace event data, it supports ${rotation} and ${pid}.

--trace-events-enabled

Enable the collection of trace event tracing information.

--trace-exit

Prints a stack trace whenever an environment is exited proactively, i.e. invoking `process.exit()`.

--trace-sigint

Prints a stack trace on SIGINT.

--trace-sync-io

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

--trace-tls

Prints TLS packet trace information to stderr.

--trace-uncaught

Print stack traces for uncaught exceptions; usually, the stack trace associated with the creation of an Error is printed, whereas this makes Node.js also print the stack trace associated with throwing the value (which does not need to be an Error instance).

Enabling this option may affect garbage collection behavior negatively.

--trace-warnings

Print stack traces for process warnings (including deprecations).

--track-heap-objects

Track heap object allocations for heap snapshots.

--unhandled-rejections=mode

Define the behavior for unhandled rejections. Can be one of `strict` (raise an error), `warn` (enforce warnings) or `none` (silence warnings).

--use-bundled-ca, --use-openssl-ca

Use bundled Mozilla CA store as supplied by current Node.js version or use OpenSSL's default CA store. The default store is selectable at build-time.

The bundled CA store, as supplied by Node.js, is a snapshot of Mozilla CA store that is fixed at release time. It is identical on all supported platforms.

Using OpenSSL store allows for external modifications of the store. For most Linux and BSD distributions, this store is maintained by the distribution maintainers and system administrators. OpenSSL CA store location is dependent on configuration of the OpenSSL library but this can be altered at runtime using environment variables.

See SSL_CERT_DIR and SSL_CERT_FILE.

--use-largepages=mode

Re-map the Node.js static code to large memory pages at startup. If supported on the target system, this will cause the Node.js static code to be moved onto 2 MiB pages instead of 4 KiB pages.

mode must have one of the following values: `off` (the default value, meaning do not map), `on` (map and ignore failure, reporting it to stderr), or `silent` (map and silently ignore failure).

--v8-options

Print V8 command-line options.

--v8-pool-size=num

Set V8's thread pool size which will be used to allocate background jobs. If set to 0 then V8 will choose an appropriate size of the thread pool based on the number of online processors. If the value provided is larger than V8's maximum, then the largest value will be chosen.

--zero-fill-buffers

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

-c, --check

Check the script's syntax without executing it. Exits with an error code if script is invalid.

-e, --eval string

Evaluate string as JavaScript.

-h, --help

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

-i, --interactive

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

-p, --print string

Identical to -e, but prints the result.

-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.js module name.

-v, --version

Print node's version.

Environment

FORCE_COLOR

Used to enable ANSI colorized output. The value may be one of: 1 , true , or an empty string to indicate 16-color support, 2 to indicate 256-color support, or 3 to indicate 16 million-color support. When used and set to a supported value, both the NO_COLOR and NODE_DISABLE_COLORS environment variables are ignored. Any other value will result in colorized output being disabled.

NO_COLOR

Alias for NODE_DISABLE_COLORS

NODE_DEBUG modules...

Comma-separated list of core modules that should print debug information.

NODE_DEBUG_NATIVE modules...

Comma-separated list of C++ core modules that should print debug information.

NODE_DISABLE_COLORS

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

NODE_EXTRA_CA_CERTS file

When set, the well-known “root” CAs (like VeriSign) will be extended with the extra certificates in file. The file should consist of one or more trusted certificates in PEM format.

If file is missing or misformatted, a message will be emitted once using process.emitWarning(), but any errors are otherwise ignored.

This environment variable is ignored when `node` runs as setuid root or has Linux file capabilities set.

The NODE_EXTRA_CA_CERTS environment variable is only read when the Node.js process is first launched. Changing the value at runtime using process.env.NODE_EXTRA_CA_CERTS has no effect on the current process.

NODE_ICU_DATA file

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

NODE_NO_WARNINGS

When set to 1, process warnings are silenced.

NODE_OPTIONS options...

A space-separated list of command-line options, which are interpreted as if they had been specified on the command line before the actual command (so they can be overridden). Node.js will exit with an error if an option that is not allowed in the environment is used, such as --print or a script file.

NODE_PATH directories...

A colon-separated list of directories prefixed to the module search path.

NODE_PENDING_DEPRECATION

When set to 1, emit pending deprecation warnings.

NODE_PRESERVE_SYMLINKS

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

NODE_REDIRECT_WARNINGS file

Write process warnings to the given file instead of printing to stderr. Equivalent to passing --redirect-warnings file on the command line.

NODE_REPL_HISTORY file

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

NODE_REPL_EXTERNAL_MODULE file

Path to a Node.js module which will be loaded in place of the built-in REPL. Overriding this value to an empty string (`''`) will use the built-in REPL.

NODE_SKIP_PLATFORM_CHECK

When set to 1, the check for a supported platform is skipped during Node.js startup. Node.js might not execute correctly. Any issues encountered on unsupported platforms will not be fixed.

NODE_TLS_REJECT_UNAUTHORIZED

When set to 0, TLS certificate validation is disabled.

NODE_V8_COVERAGE dir

When set, Node.js writes JavaScript code coverage information to dir.

OPENSSL_CONF 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.

If the --openssl-config command-line option is used, this environment variable is ignored.

SSL_CERT_DIR dir

If --use-openssl-ca is enabled, this overrides and sets OpenSSL's directory containing trusted certificates.

SSL_CERT_FILE file

If --use-openssl-ca is enabled, this overrides and sets OpenSSL's file containing trusted certificates.

TZ

Specify the timezone configuration.

UV_THREADPOOL_SIZE size

Sets the number of threads used in libuv's threadpool to size.