Try to be a bit more consistent on all platforms:

nnorwitz · nnorwitz · commit 72c2c062d71c · 2006-03-09T05:58:11.000Z
python .
  python &lt; .

both print a message, return non-zero and do not core dump.
diff --git a/Lib/test/test_cmd_line.py b/Lib/test/test_cmd_line.py
@@ -16,19 +16,8 @@ def exit_code(self, cmd_line):
         return subprocess.call([sys.executable, cmd_line], stderr=subprocess.PIPE)
 
     def test_directories(self):
-        if sys.platform == 'win32':
-            # Exit code for "python .", Error 13: permission denied = 2
-            expected_exit_code = 2
-        elif sys.platform.startswith('freebsd'):
-            # On FreeBSD, it more likely raise SyntaxError for binary
-            # directory data.
-            expected_exit_code = 1
-        else:
-            # Linux has no problem with "python .", Exit code = 0
-            expected_exit_code = 0
-        self.assertEqual(self.exit_code('.'), expected_exit_code)
-
-        self.assertTrue(self.exit_code('< .') != 0)
+        self.assertNotEqual(self.exit_code('.'), 0)
+        self.assertNotEqual(self.exit_code('< .'), 0)
 
     def verify_valid_flag(self, cmd_line):
         data = self.start_python(cmd_line)
diff --git a/Modules/main.c b/Modules/main.c
@@ -364,7 +364,8 @@ Py_Main(int argc, char **argv)
 				struct stat sb;
 				if (fstat(fileno(fp), &sb) == 0 &&
 				    S_ISDIR(sb.st_mode)) {
-					fprintf(stderr, "%s: warning '%s' is a directory\n", argv[0], filename);
+					fprintf(stderr, "%s: '%s' is a directory, cannot continue\n", argv[0], filename);
+					return 1;
 				}
 			}
 		}
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
@@ -1037,7 +1037,10 @@ _PySys_Init(void)
 		struct stat sb;
 		if (fstat(fileno(stdin), &sb) == 0 &&
 		    S_ISDIR(sb.st_mode)) {
-			Py_FatalError("<stdin> is a directory");
+			/* There's nothing more we can do. */
+			/* Py_FatalError() will core dump, so just exit. */
+			PySys_WriteStderr("Python error: <stdin> is a directory, cannot continue\n");
+			exit(EXIT_FAILURE);
 		}
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -364,7 +364,8 @@ Py_Main(int argc, char **argv)`
`364`	`364`	`struct stat sb;`
`365`	`365`	`if (fstat(fileno(fp), &sb) == 0 &&`
`366`	`366`	`S_ISDIR(sb.st_mode)) {`
`367`		`- fprintf(stderr, "%s: warning '%s' is a directory\n", argv[0], filename);`
	`367`	`+ fprintf(stderr, "%s: '%s' is a directory, cannot continue\n", argv[0], filename);`
	`368`	`+ return 1;`
`368`	`369`	`}`
`369`	`370`	`}`
`370`	`371`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1037,7 +1037,10 @@ _PySys_Init(void)`
`1037`	`1037`	`struct stat sb;`
`1038`	`1038`	`if (fstat(fileno(stdin), &sb) == 0 &&`
`1039`	`1039`	`S_ISDIR(sb.st_mode)) {`
`1040`		`- Py_FatalError("<stdin> is a directory");`
	`1040`	`+ /* There's nothing more we can do. */`
	`1041`	`+ /* Py_FatalError() will core dump, so just exit. */`
	`1042`	`+ PySys_WriteStderr("Python error: <stdin> is a directory, cannot continue\n");`
	`1043`	`+ exit(EXIT_FAILURE);`
`1041`	`1044`	`}`
`1042`	`1045`	`}`
`1043`	`1046`