capabilities: don't show progress bar when stderr is redirected to a file

capa/capabilities/dynamic.py

@@ -6,6 +6,7 @@
 # Unless required by applicable law or agreed to in writing, software distributed under the License
 #  is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and limitations under the License.
+import sys
 import logging
 import itertools
 import collections
@@ -146,6 +147,10 @@ def find_dynamic_capabilities(
                 # to disable progress completely
                 def pbar(s, *args, **kwargs):
                     return s
+            elif not sys.stderr.isatty():
+                # don't display progress bar when stderr is redirected to a file
+                def pbar(s, *args, **kwargs):
+                    return s
 
             processes = list(extractor.get_processes())
 

capa/capabilities/static.py

@@ -6,6 +6,7 @@
 # Unless required by applicable law or agreed to in writing, software distributed under the License
 #  is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and limitations under the License.
+import sys
 import time
 import logging
 import itertools
@@ -155,6 +156,10 @@ def find_static_capabilities(
                 # to disable progress completely
                 def pbar(s, *args, **kwargs):
                     return s
+            elif not sys.stderr.isatty():
+                # don't display progress bar when stderr is redirected to a file
+                def pbar(s, *args, **kwargs):
+                    return s
 
             functions = list(extractor.get_functions())
             n_funcs = len(functions)