Add --active-only flag to only run pywal on active ttys

pywal/__main__.py

@@ -67,6 +67,9 @@ def get_args():
     arg.add_argument("--vte", action="store_true",
                      help="Fix text-artifacts printed in VTE terminals.")
 
+    arg.add_argument("--active-only", action="store_true",
+                     help="Only send sequences to active terminals.")
+
     arg.add_argument("-c", action="store_true",
                      help="Delete all cached colorschemes.")
 
@@ -200,7 +203,9 @@ def parse_args(parser):
     if args.p:
         theme.save(colors_plain, args.p, args.l)
 
-    sequences.send(colors_plain, to_send=not args.s, vte_fix=args.vte)
+    sequences.send(
+        colors_plain, to_send=not args.s,
+        vte_fix=args.vte, only_active=args.active_only)
 
     if sys.stdout.isatty():
         colors.palette()

pywal/sequences.py

@@ -70,7 +70,8 @@ def create_sequences(colors, vte_fix=False):
     return "".join(sequences)
 
 
-def send(colors, cache_dir=CACHE_DIR, to_send=True, vte_fix=False):
+def send(colors, cache_dir=CACHE_DIR, to_send=True,
+         vte_fix=False, only_active=False):
     """Send colors to all open terminals."""
     if OS == "Darwin":
         tty_pattern = "/dev/ttys00[0-9]*"
@@ -82,8 +83,13 @@ def send(colors, cache_dir=CACHE_DIR, to_send=True, vte_fix=False):
 
     # Writing to "/dev/pts/[0-9] lets you send data to open terminals.
     if to_send:
+        ttys = []
+        if only_active:
+            ttys = util.fetch_active_ttys()
+
         for term in glob.glob(tty_pattern):
-            util.save_file(sequences, term)
+            util.save_to_tty(
+                    sequences, term, active_ttys=ttys)
 
     util.save_file(sequences, os.path.join(cache_dir, "sequences"))
     logging.info("Set terminal colors.")

pywal/util.py

@@ -134,6 +134,33 @@ def save_file(data, export_file):
         logging.warning("Couldn't write to %s.", export_file)
 
 
+def save_to_tty(data, tty_name, active_ttys=[]):
+    """Write data to a tty."""
+    if active_ttys:
+        if os.path.basename(tty_name) not in active_ttys:
+            logging.info("Not saving to inactive tty %s.", tty_name)
+            return
+    save_file(data, tty_name)
+
+
+def fetch_active_ttys():
+    try:
+        out, err = subprocess.Popen(
+                ["who"], stdout=subprocess.PIPE).communicate()
+    except FileNotFoundError:
+        # who is not installed on the machine
+        return None
+
+    if err:
+        logging.warning(
+            "Received stderr output while checking active ttys: %s",
+            err.decode('utf-8'))
+        return None
+    lines = out.decode('utf-8').split("\n")
+    # The format is `username tty ...` and we just want tty
+    return [line.split(' ')[1] for line in lines if line]
+
+
 def save_file_json(data, export_file):
     """Write data to a json file."""
     create_dir(os.path.dirname(export_file))

tests/test_util.py

@@ -46,6 +46,26 @@ class TestUtil(unittest.TestCase):
         result = os.path.isfile(tmp_file)
         self.assertTrue(result)
 
+    def test_save_to_tty_active_tty_saves(self):
+        """> Save colors to an active tty."""
+        tmp_file = "/tmp/test_tty_file_active"
+        util.save_to_tty("Hello, World!", tmp_file, ["test_tty_file_active"])
+        result = os.path.isfile(tmp_file)
+        self.assertTrue(result)
+
+    def test_save_to_tty_inactive_does_not_save(self):
+        """> Does not save colors to an inactive tty."""
+        tmp_file = "/tmp/test_tty_file_inactive"
+        util.save_to_tty("Hello, World!", tmp_file, ["test_tty_file_active"])
+        result = os.path.isfile(tmp_file)
+        self.assertFalse(result)
+
+    def test_save_to_tty_inactive_no_ttys_saves(self):
+        tmp_file = "/tmp/test_tty_file_inactive_save"
+        util.save_to_tty("Hello, World!", tmp_file, [])
+        result = os.path.isfile(tmp_file)
+        self.assertTrue(result)
+
     def test_create_dir(self):
         """> Create a directory."""
         tmp_dir = "/tmp/test_dir"