Use "which" to look for grep / find.

Author: cowboy

package.json

@@ -33,7 +33,8 @@
     "grunt-contrib-watch": "~0.5.3",
     "grunt": "~0.4.1",
     "async": "~0.2.9",
-    "diff": "~1.0.7"
+    "diff": "~1.0.7",
+    "which": "~1.0.5"
   },
   "keywords": [
     "exit",

test/exit_test.js

@@ -25,14 +25,27 @@ var exec = require('child_process').exec;
 var async = require('async');
 var jsdiff = require('diff');
 
+var _which = require('which').sync;
+function which(command) {
+  try {
+    return _which(command);
+  } catch (err) {
+    return false;
+  }
+}
+
+// Look for grep first (any OS). If not found (but on Windows) look for find,
+// which is Windows' horribly crippled grep alternative.
+var grep = which('grep') || process.platform === 'win32' && which('find');
+
 function run(command, options, callback) {
   if (typeof options === 'function') {
     callback = options;
     options = {};
   }
   command += ' 2>&1';
   if (options.pipe) {
-    command += ' | ' + (process.platform === 'win32' ? 'find' : 'grep') + ' "std"';
+    command += ' | ' + grep + ' "std"';
   }
   exec(command, function(error, stdout) {
     callback(command, error ? error.code : 0, stdout);
@@ -69,6 +82,12 @@ exports['exit'] = {
     process.chdir(this.origCwd);
     done();
   },
+  'grep': function(test) {
+    test.expect(1);
+    // Many unit tests depend on this.
+    test.ok(grep, 'A suitable "grep" or "find" program was not found in the PATH.');
+    test.done();
+  },
   'stdout stderr': function(test) {
     var counts = [10, 100, 1000];
     test.expect(counts.length);