Disable coloring when requested/on Windows/no tty

qutebrowser/app.py

@@ -171,6 +171,8 @@ class QuteBrowser(QApplication):
                             "(empty for no config storage)")
         parser.add_argument('-d', '--debug', help="Turn on debugging options.",
                             action='store_true')
+        parser.add_argument('--nocolor', help="Turn off colored logging.",
+                            action='store_false', dest='color')
         parser.add_argument('command', nargs='*', help="Commands to execute "
                             "on startup.", metavar=':command')
         # URLs will actually be in command

qutebrowser/utils/log.py

@@ -17,6 +17,8 @@
 
 """Loggers and utilities related to logging."""
 
+import os
+import sys
 import logging
 from logging import getLogger
 from collections import deque
@@ -70,16 +72,15 @@ def init_log(args):
     datefmt = '%H:%M:%S'
 
     if numeric_level <= logging.DEBUG:
-        console_fmt = (extended_fmt if ColoredFormatter is None
-                       else extended_fmt_colored)
+        console_fmt = extended_fmt
+        console_fmt_colored = extended_fmt_colored
     else:
-        console_fmt = (simple_fmt if ColoredFormatter is None
-                       else simple_fmt_colored)
-    if ColoredFormatter is None:
-        console_formatter = logging.Formatter(console_fmt, datefmt, '{')
-    else:
-        console_formatter = ColoredFormatter(console_fmt, datefmt,
-            log_colors={
+        console_fmt = simple_fmt
+        console_fmt_colored = simple_fmt_colored
+    if (ColoredFormatter is not None and os.name == 'posix' and
+            sys.stderr.isatty() and args.color):
+        console_formatter = ColoredFormatter(
+            console_fmt_colored, datefmt, log_colors={
                 'DEBUG':    'cyan',
                 'INFO':     'green',
                 'WARNING':  'yellow',
@@ -87,6 +88,8 @@ def init_log(args):
                 'CRITICAL': 'red',
             }
         )
+    else:
+        console_formatter = logging.Formatter(console_fmt, datefmt, '{')
     console_handler = logging.StreamHandler()
     console_handler.addFilter(logfilter)
     console_handler.setLevel(level)