man > nodejs(1)

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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 exe‐
cuted 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.

--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 work‐
ing directory with a generated file name.

--cpu-prof-dir
The directory where the CPU profiles generated by --cpu-prof will be placed. The de‐
fault 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 direc‐
tory. 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`.

--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` mod‐
ule.

--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-global-customevent
Expose the CustomEvent on the global scope.

--experimental-global-webcrypto
Expose the Web Crypto API on the global scope.

--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-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.

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

--no-experimental-repl-await
Disable top-level await keyword support in REPL.

--experimental-specifier-resolution
Select extension resolution algorithm for ES Modules; either 'explicit' (default) or
'node'.

--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 re‐
quired 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=[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 in‐
stances 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 inter‐
operability with non-conformant HTTP implementations. It may also allow request smug‐
gling 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 plat‐
forms 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 con‐
trolled 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 applica‐
tion. 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 prede‐
fined) 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 Win‐
dows). Default signal is SIGUSR2.

--report-uncaught-exception
Enables diagnostic report to be generated on un-caught exceptions. Useful when in‐
specting JavaScript stack in conjunction with native stack and other runtime environ‐
ment data.

--secure-heap=n
Specify the size of the OpenSSL secure heap. Any value less than 2 disables the se‐
cure 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-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` op‐
tion set.

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

--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 in‐
stance).

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 er‐
ror), `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 indi‐
cate 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 overrid‐
den). Node.js will exit with an error if an option that is not allowed in the envi‐
ronment 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. Over‐
riding 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 ig‐
nored.

SSL_CERT_DIR dir
If --use-openssl-ca is enabled, this overrides and sets OpenSSL's directory contain‐
ing 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.