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Manual: nodejs

NAME
node — server-side JavaScript runtime

DESCRIPTION
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 de‐
fault 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 cur‐
rent 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.

--entry-url
Interpret the entry point as a URL.

--experimental-addon-modules
Enable experimental addon module support.

--experimental-default-type=type
Interpret as either ES modules or CommonJS modules input via --eval or STDIN, when --in‐
put-type is unspecified;

--experimental-config-file
Specifies the configuration file to load.

--experimental-default-config-file
Enable support for automatically loading node.config.json.

--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.

--permission
Enable the permission model.

--experimental-shadow-realm
Use this flag to enable ShadowRealm support.

--experimental-test-coverage
Enable code coverage in the test runner.

--experimental-test-isolation=mode
Configures the type of test isolation used in the test runner.

--experimental-test-module-mocks
Enable module mocking in the test runner.

--experimental-transform-types
Enable transformation of TypeScript-only syntax into JavaScript code.

--experimental-eventsource
Enable experimental support for the EventSource Web API.

--no-experimental-fetch
Disable experimental support for the Fetch API.

--no-experimental-websocket
Disable experimental support for the WebSocket API.

--experimental-webstorage
Enable experimental support for the Web Storage 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.

--no-experimental-sqlite
Disable the experimental node:sqlite module.

--no-experimental-strip-types
Disable experimental type-stripping for TypeScript files.

--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-inspector-network-resource
Enable experimental support for inspector network resources.

--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 require‐
ments 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 direc‐
tory 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. De‐
fault 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 interoperabil‐
ity 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.

--localstorage-file=file
The file used to store localStorage data.

--max-http-header-size=size
Specify the maximum size of HTTP headers in bytes. Defaults to 16 KiB.

--max-old-space-size-percentage=percentage
Sets the maximum memory size of V8's old memory section as a percentage of available system
memory. This flag takes precedence over --max-old-space-size when both are specified. The
percentage parameter must be a number greater than 0 and up to 100, representing the percent‐
age of available system memory to allocate to the V8 heap.

Note: This flag utilizes --max-old-space-size, which may be unreliable on 32-bit platforms
due to integer overflow issues.

--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.

--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 ab‐
solute 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). De‐
fault 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-coverage-branches=threshold
Require a minimum threshold for branch coverage (0 - 100).

--test-coverage-exclude
A glob pattern that excludes matching files from the coverage report

--test-coverage-functions=threshold
Require a minimum threshold for function coverage (0 - 100).

--test-coverage-include
A glob pattern that only includes matching files in the coverage report

--test-coverage-lines=threshold
Require a minimum threshold for line coverage (0 - 100).

--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 /.

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

--test-timeout
A number of milliseconds the test execution will fail after.

--test-update-snapshots
Regenerates the snapshot file used by the test runner for snapshot testing.

--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 en‐
abled 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 cre‐
ation of an Error is printed, whereas this makes Node.js also print the stack trace associ‐
ated 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 adminis‐
trators. 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-env-proxy
Parse proxy settings from HTTP_PROXY/HTTPS_PROXY/NO_PROXY environment variables and apply the
setting in global HTTP/HTTPS clients.

--use-system-ca
Use the trusted CA certificates present in the system store, in addition to the certificates
in the bundled Mozilla CA store and certificates from `NODE_EXTRA_CA_CERTS`. On Windows and
macOS, it uses system APIs to integrate additional trusted certificates. On other platforms
it is similar to `--use-openssl-ca` with the difference being that it caches the certificates
on first load, and the system certificates are added in a complementary manner without re‐
placing certificates from other sources. This flag supersedes `--use-openssl-ca`.

--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 proces‐
sors. If the value provided is larger than V8's maximum, then the largest value will be cho‐
sen.

--watch
Starts Node.js in watch mode. When in watch mode, changes in the watched files cause the
Node.js process to restart.

By default, watch mode will watch the entry point and any required or imported module. Use
--watch-path to specify what paths to watch.

--watch-path
Starts Node.js in watch mode and specifies what paths to watch. When in watch mode, changes
in the watched paths cause the Node.js process to restart.

This will turn off watching of required or imported modules, even when used in combination
with --watch.

--watch-kill-signal
Customizes the signal sent to the process on watch mode restarts.

--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 in‐
valid.

-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 mil‐
lion-color support. When used and set to a supported value, both the NO_COLOR and NODE_DIS‐
ABLE_COLORS environment variables are ignored. Any other value will result in colorized out‐
put being disabled.

NO_COLOR
Alias for NODE_DISABLE_COLORS

NODE_COMPILE_CACHE dir
Enable the module compile cache for the Node.js instance.

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_COMPILE_CACHE
Disable the module compile cache for the Node.js instance.

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 certifi‐
cates 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 capa‐
bilities 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_PENDING_PIPE_INSTANCES
Set the number of pending pipe instance handles when the pipe server is waiting for connec‐
tions. This setting applies to Windows only.

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 pass‐
ing --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_TEST_CONTEXT
When set to 'child' , test reporter options will be overridden and test output will be sent
to stdout in the TAP format. If any other value is provided, Node.js makes no guarantees
about the reporter format used or its stability.

NODE_TLS_REJECT_UNAUTHORIZED
When set to 0, TLS certificate validation is disabled.

NODE_USE_ENV_PROXY
When enabled, Node.js parses the HTTP_PROXY , HTTPS_PROXY and NO_PROXY environment variables
during startup, and tunnels requests over the specified proxy.

This currently only affects requests sent over fetch(). Support for other built-in http and
https methods is under way.

NODE_USE_SYSTEM_CA
Similar to --use-system-ca. Use the trusted CA certificates present in the system store, in
addition to the certificates in the bundled Mozilla CA store and certificates from `NODE_EX‐
TRA_CA_CERTS`.

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.

BUGS
Bugs are tracked in GitHub Issues: https://github.com/nodejs/node/issues

Node.js also includes external libraries that are available under a variety of licenses. See
https://github.com/nodejs/node/blob/HEAD/LICENSE for the full license text.

Manual: nodejs

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