Add 'x' command argument for tracing

sh.py

@@ -1273,6 +1273,8 @@ class Command:
         # sometimes we may return just a plain unicode string
         "return_cmd": False,
         "async": False,
+        # whether to echo each command before executing it
+        "x": False,
     }
 
     # this is a collection of validators to make sure the special kwargs make
@@ -1478,6 +1480,8 @@ def __call__(self, *args, **kwargs):
         final_args = split_args
 
         cmd.extend(final_args)
+        if call_args["x"]:
+            print(" ".join(cmd))
 
         # if we're running in foreground mode, we need to completely bypass
         # launching a RunningCommand and OProc and just do a spawn

tests/sh_test.py

@@ -3233,6 +3233,18 @@ def test_ok_code_ignores_bad_sig_exception(self):
             else:
                 self.assertEqual(p.exit_code, -sig)
 
+    def test_x(self):
+        import sh
+
+        stdout = StringIO()
+        original_stdout = sys.stdout
+        sys.stdout = stdout
+
+        echo = sh.echo("hello", "world", _x=True, _return_cmd=True)
+
+        self.assertIn(str(" ".join(echo.cmd)), stdout.getvalue().strip())
+        sys.stdout = original_stdout
+
 
 class MockTests(BaseTests):
     def test_patch_command_cls(self):