Disable output if terminal lacks capabilities

2 files changed, 8 insertions, 1 deletions

diff --git a/ttystatus/messager.py b/ttystatus/messager.py
index 5f08690..f9ab912 100644
--- a/ttystatus/messager.py
+++ b/ttystatus/messager.py
@@ -46,6 +46,9 @@ class Messager(object):
         except IOError:
             self._enabled = False
 
+        if not self._terminal.has_capabilities():
+            self._enabled = False
+
         self._area = ttystatus.AreaManager()
         self._area.set_terminal(self._terminal)
 
@@ -122,6 +125,6 @@ class Messager(object):
 
     def finish(self):
         '''Finalize output.'''
-        if self._cached_message is not None:
+        if self._enabled and self._cached_message is not None:
             self.write(self._cached_message)
             self._terminal.write('\n')
diff --git a/ttystatus/tty.py b/ttystatus/tty.py
index f37b825..21e75cc 100644
--- a/ttystatus/tty.py
+++ b/ttystatus/tty.py
@@ -31,6 +31,10 @@ class PhysicalTerminal(object):
         self._terminal = open('/dev/tty', 'wb')
         curses.setupterm(None, self._terminal.fileno())
 
+    def has_capabilities(self):
+        return all(curses.tigetstr(x) is not None
+                   for x in ['cuu', 'cud', 'cr', 'el'])
+
     def get_up_sequence(self):
         return curses.tparm(curses.tigetstr('cuu'), 1)