issue #55: add BUNYAN_NO_COLOR envvar support

CHANGES.md

@@ -2,7 +2,9 @@
 
 ## bunyan 0.16.5 (not yet released)
 
-(nothing yet)
+- issue #55: Add support for `BUNYAN_NO_COLOR` environment variable to
+  turn off all output coloring. This is still overridden by the `--color`
+  and `--no-color` options.
 
 
 ## bunyan 0.16.4

bin/bunyan

@@ -191,6 +191,10 @@ function printHelp() {
     console.log("    %s %d", n, levelFromName[name]);
   });
   console.log("");
+  console.log("Environment Variables:");
+  console.log("  BUNYAN_NO_COLOR    Set to a non-empty value to force no output ");
+  console.log("                     coloring. See '--no-color'.");
+  console.log("");
   console.log("See <https://github.com/trentm/node-bunyan> for more complete docs.");
   console.log("Please report bugs to <https://github.com/trentm/node-bunyan/issues>.");
 }
@@ -314,7 +318,7 @@ function parseArgv(argv) {
   var parsed = {
     args: [],
     help: false,
-    color: process.stdout.isTTY,
+    color: null,
     outputMode: OM_PAUL,
     jsonIndent: 2,
     level: null,
@@ -1114,6 +1118,14 @@ function main(argv) {
       opts.pid, opts.args.join(' '));
     return drainStdoutAndExit(1);
   }
+  if (opts.color === null) {
+    if (process.env.BUNYAN_NO_COLOR &&
+        process.env.BUNYAN_NO_COLOR.length > 0) {
+      opts.color = false;
+    } else {
+      opts.color = process.stdout.isTTY;
+    }
+  }
   var stylize = (opts.color ? stylizeWithColor : stylizeWithoutColor);
 
   var retval = 0;

docs/bunyan.1

@@ -197,6 +197,12 @@ Each of these probes has a single argument: the string that would be written to
 .P
 See \fIhttps://github\.com/trentm/node\-bunyan#dtrace\-support\fR for more details\.
 .
+.SH "ENVIRONMENT"
+.
+.TP
+\fBBUNYAN_NO_COLOR\fR
+Set to a non\-empty value to force no output coloring\. See \'\-\-no\-color\'\.
+.
 .SH "PROJECT & BUGS"
 \fBbunyan\fR is written in JavaScript and requires node\.js (\fBnode\fR)\. The project lives at \fIhttps://github\.com/trentm/node\-bunyan\fR and is published to npm as "bunyan"\.
 .

docs/bunyan.1.html

@@ -66,6 +66,7 @@
     <a href="#LOG-LEVELS">LOG LEVELS</a>
     <a href="#OUTPUT-FORMATS">OUTPUT FORMATS</a>
     <a href="#DTRACE-SUPPORT">DTRACE SUPPORT</a>
+    <a href="#ENVIRONMENT">ENVIRONMENT</a>
     <a href="#PROJECT-BUGS">PROJECT &amp; BUGS</a>
     <a href="#LICENSE">LICENSE</a>
     <a href="#COPYRIGHT">COPYRIGHT</a>
@@ -230,6 +231,13 @@ the log message is less than that of any stream.</p>
 
 <p>See <a href="https://github.com/trentm/node-bunyan#dtrace-support" data-bare-link="true">https://github.com/trentm/node-bunyan#dtrace-support</a> for more details.</p>
 
+<h2 id="ENVIRONMENT">ENVIRONMENT</h2>
+
+<dl>
+<dt><code>BUNYAN_NO_COLOR</code></dt><dd>Set to a non-empty value to force no output coloring. See '--no-color'.</dd>
+</dl>
+
+
 <h2 id="PROJECT-BUGS">PROJECT &amp; BUGS</h2>
 
 <p><code>bunyan</code> is written in JavaScript and requires node.js (<code>node</code>). The project

docs/bunyan.1.ronn

@@ -156,6 +156,12 @@ the log message is less than that of any stream.
 See <https://github.com/trentm/node-bunyan#dtrace-support> for more details.
 
 
+## ENVIRONMENT
+
+  * `BUNYAN_NO_COLOR`:
+    Set to a non-empty value to force no output coloring. See '--no-color'.
+
+
 ## PROJECT & BUGS
 
 `bunyan` is written in JavaScript and requires node.js (`node`). The project