Made output pipe to shell command featuer much more reliable

The ability to pipe the output of a cmd2 command to a shell command no longer depends on the presence of the "cat" shell command.

It now directly pipes the contents of a file as the stdin to the shell command.

2 files changed, 24 insertions, 18 deletions

diff --git a/cmd2.py b/cmd2.py
index 10b12516..ca431279 100755
--- a/cmd2.py
+++ b/cmd2.py
@@ -900,17 +900,16 @@ class Cmd(cmd.Cmd):
                 self.kept_state = None
 
                 if statement.parsed.pipeTo:
-                    # cat the tempfile and pipe the output to the specified shell command
-                    cat_command = 'cat'
-                    p1 = subprocess.Popen([cat_command, self._temp_filename], stdout=subprocess.PIPE)
-                    p2 = subprocess.Popen(shlex.split(statement.parsed.pipeTo), stdin=p1.stdout, stdout=subprocess.PIPE)
-                    p1.stdout.close()  # Allow p1 to receive a SIGPIPE if p2 exits.
-                    output, err = p2.communicate()
-
-                    if six.PY3:
-                        self.stdout.write(output.decode())
-                    else:
-                        self.stdout.write(output)
+                    # Pipe the contents of tempfile to the specified shell command
+                    with open(self._temp_filename) as fd:
+                        pipe_proc = subprocess.Popen(shlex.split(statement.parsed.pipeTo), stdin=fd,
+                                                     stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+                        output, err = pipe_proc.communicate()
+
+                        if six.PY3:
+                            self.stdout.write(output.decode())
+                        else:
+                            self.stdout.write(output)
 
                     os.remove(self._temp_filename)
                     self._temp_filename = None
diff --git a/tests/test_cmd2.py b/tests/test_cmd2.py
index adf47d31..efc82294 100644
--- a/tests/test_cmd2.py
+++ b/tests/test_cmd2.py
@@ -402,15 +402,22 @@ def test_input_redirection(base_app, request):
 
 
 def test_pipe_to_shell(base_app):
-    # Get help on help and pipe it's output to the input of the word count shell command
-    out = run_cmd(base_app, 'help help | wc')
-
     if sys.platform == "win32":
-        expected = normalize("1      11      71")
+        # Windows
+        # Get help menu and pipe it's output to the sort shell command
+        out = run_cmd(base_app, 'help | sort')
+        expected = normalize("""
+_relative_load  edit  history  pause  pyscript  run   set    shortcuts
+========================================
+cmdenvironment  help  load     py     quit      save  shell  show
+Documented commands (type help <topic>):""")
+        assert out == expected
     else:
-        expected = normalize("1      11      70")
-
-    assert out[0].strip() == expected[0].strip()
+        # Mac and Linux
+        # Get help on help and pipe it's output to the input of the word count shell command
+        out = run_cmd(base_app, 'help help | wc')
+        expected = normalize("1 11 70")
+        assert out[0].strip() == expected[0].strip()
 
 
 def test_send_to_paste_buffer(base_app):