doc: document the NO_COLOR and FORCE_COLOR env vars

Signed-off-by: James M Snell <[email protected]> Fixes: nodejs#37404
jasnell · Feb 23, 2021 · 1d4d8b2 · 1d4d8b2
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diff --git a/doc/api/cli.md b/doc/api/cli.md
@@ -1264,6 +1264,18 @@ Print node's version.
 
 ## Environment variables
 
+### `FORCE_COLOR=[1, 2, 3]`
+
+The `FORCE_COLOR` environment variable is used to
+enable ANSI colorized output. The value may be:
+
+* `1` or `true` to indicate 16-color support,
+* `2` to indicate 256-color support, or
+* `3` to indicate 16 million-color support.
+
+When `FORCE_COLOR` is used and set to a supported value, both the `NO_COLOR`,
+and `NODE_DISABLE_COLORS` environment variables are ignored.
+
 ### `NODE_DEBUG=module[,…]`
 <!-- YAML
 added: v0.1.32
@@ -1609,6 +1621,10 @@ and the line lengths of the source file (in the key `lineLengths`).
 }
 ```
 
+### `NO_COLOR=1`
+
+[`NO_COLOR`][]  is an alias for `NODE_DISABLE_COLORS`.
+
 ### `OPENSSL_CONF=file`
 <!-- YAML
 added: v6.11.0
@@ -1704,6 +1720,7 @@ $ node --max-old-space-size=1536 index.js
 [`Buffer`]: buffer.md#buffer_class_buffer
 [`CRYPTO_secure_malloc_init`]: https://www.openssl.org/docs/man1.1.0/man3/CRYPTO_secure_malloc_init.html
 [`NODE_OPTIONS`]: #cli_node_options_options
+[`NO_COLOR`]: https://no-color.org
 [`SlowBuffer`]: buffer.md#buffer_class_slowbuffer
 [`process.setUncaughtExceptionCaptureCallback()`]: process.md#process_process_setuncaughtexceptioncapturecallback_fn
 [`tls.DEFAULT_MAX_VERSION`]: tls.md#tls_tls_default_max_version

diff --git a/doc/node.1 b/doc/node.1
@@ -530,6 +530,23 @@ Print node's version.
 .\" =====================================================================
 .Sh ENVIRONMENT
 .Bl -tag -width 6n
+.It Ev FORCE_COLOR
+Used to enable ANSI colorized output. The value may be one of:
+.Ar 1
+or
+.Ar true
+to
+indicate 16-color support,
+.Ar 2
+to indicate 256-color support, or
+.Ar 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.
+.
+.It Ev NO_COLOR
+Alias for NODE_DISABLE_COLORS
+.
 .It Ev NODE_DEBUG Ar modules...
 Comma-separated list of core modules that should print debug information.
 .

diff --git a/lib/internal/main/print_help.js b/lib/internal/main/print_help.js
@@ -29,6 +29,9 @@ for (const key of ObjectKeys(types))
 // so we gather the documentation here.
 const { hasIntl, hasSmallICU, hasNodeOptions } = internalBinding('config');
 const envVars = new SafeMap(ArrayPrototypeConcat([
+  ['FORCE_COLOR', { helpText: "when set to 'true', 1, 2, or 3, causes " +
+   'NO_COLOR and NODE_DISABLE_COLORS to be ignored.' }],
+  ['NO_COLOR', { helpText: 'Alias for NODE_DISABLE_COLORS' }],
   ['NODE_DEBUG', { helpText: "','-separated list of core modules that " +
     'should print debug information' }],
   ['NODE_DEBUG_NATIVE', { helpText: "','-separated list of C++ core debug " +