Prevent error messages/exit code 120 after exiting on EPIPE

CHANGES.rst

@@ -39,6 +39,7 @@ Unreleased
 -   Add documentation for ``ignore_unkown_options``. (`#684`_)
 -   Add bright colors support for ``click.style`` and fix the reset option for parameters ``fg`` and ``bg``. (`#703`_, `#809`_)
 -   Add ``show_envvar`` for showing environment variables in help. (`#710`_)
+-   Avoid ``BrokenPipeError`` during interpreter shutdown when stdout or stderr is a closed pipe. (`#712`_, `#1106`_)
 -   Document customizing option names. (`#725`_, `#1016`_)
 -   Disable ``sys._getframes()`` on Python interpreters that don't support it. (`#728`_)
 -   Fix bug in test runner when calling ``sys.exit`` with ``None``. (`#739`_)
@@ -129,6 +130,7 @@ Unreleased
 .. _#706: https://github.com/pallets/click/pull/706
 .. _#709: https://github.com/pallets/click/pull/709
 .. _#710: https://github.com/pallets/click/pull/710
+.. _#712: https://github.com/pallets/click/pull/712
 .. _#719: https://github.com/pallets/click/issues/719
 .. _#725: https://github.com/pallets/click/issues/725
 .. _#728: https://github.com/pallets/click/pull/728
@@ -214,6 +216,7 @@ Unreleased
 .. _#1061: https://github.com/pallets/click/pull/1061
 .. _#1088: https://github.com/pallets/click/issues/1088
 .. _#1105: https://github.com/pallets/click/pull/1105
+.. _#1106: https://github.com/pallets/click/pull/1106
 .. _#1108: https://github.com/pallets/click/pull/1108
 .. _#1115: https://github.com/pallets/click/pull/1115
 

click/core.py

@@ -7,7 +7,8 @@
 from functools import update_wrapper
 
 from .types import convert_type, IntRange, BOOL
-from .utils import make_str, make_default_short_help, echo, get_os_args
+from .utils import PacifyFlushWrapper, make_str, make_default_short_help, \
+     echo, get_os_args
 from .exceptions import ClickException, UsageError, BadParameter, Abort, \
      MissingParameter, Exit
 from .termui import prompt, confirm, style
@@ -734,6 +735,8 @@ def main(self, args=None, prog_name=None, complete_var=None,
                 sys.exit(e.exit_code)
             except IOError as e:
                 if e.errno == errno.EPIPE:
+                    sys.stdout = PacifyFlushWrapper(sys.stdout)
+                    sys.stderr = PacifyFlushWrapper(sys.stderr)
                     sys.exit(1)
                 else:
                     raise

click/utils.py

@@ -414,3 +414,27 @@ def get_app_dir(app_name, roaming=True, force_posix=False):
     return os.path.join(
         os.environ.get('XDG_CONFIG_HOME', os.path.expanduser('~/.config')),
         _posixify(app_name))
+
+
+class PacifyFlushWrapper(object):
+    """This wrapper is used to catch and suppress BrokenPipeErrors resulting
+    from ``.flush()`` being called on broken pipe during the shutdown/final-GC
+    of the Python interpreter. Notably ``.flush()`` is always called on
+    ``sys.stdout`` and ``sys.stderr``. So as to have minimal impact on any
+    other cleanup code, and the case where the underlying file is not a broken
+    pipe, all calls and attributes are proxied.
+    """
+
+    def __init__(self, wrapped):
+        self.wrapped = wrapped
+
+    def flush(self):
+        try:
+            self.wrapped.flush()
+        except IOError as e:
+            import errno
+            if e.errno != errno.EPIPE:
+                raise
+
+    def __getattr__(self, attr):
+        return getattr(self.wrapped, attr)