Make the OS-level stdout/stderr capture work in the frontends.

IPython/frontend/prefilterfrontend.py

@@ -21,8 +21,7 b' from linefrontendbase import LineFrontEndBase, common_prefix'
 
 from IPython.ipmaker import make_IPython
 from IPython.ipapi import IPApi
-from IPython.kernel.core.file_like import FileLike
-from IPython.kernel.core.output_trap import OutputTrap
+from IPython.kernel.core.redirector_output_trap import RedirectorOutputTrap
 
 from IPython.genutils import Term
 import pydoc
@@ -60,17 +59,9 b' class PrefilterFrontEnd(LineFrontEndBase):'
         # Make sure the raw system call doesn't get called, as we don't
         # have a stdin accessible.
         self._ip.system = xterm_system
-        # Redefine a serie of magics to avoid os.system:
-        # FIXME: I am redefining way too much magics.
-        for alias_name, (_, alias_value) in \
-                    _ip.IP.shell.alias_table.iteritems():
-            magic = lambda s : _ip.magic('sx %s %s' % (alias_value, s))
-            setattr(_ip.IP, 'magic_%s' % alias_name, magic)
-        # FIXME: I should create a real file-like object dedicated to this
-        # terminal
-        self.shell.output_trap = OutputTrap(
-                                out=FileLike(write_callback=self.write),
-                                err=FileLike(write_callback=self.write),
+        self.shell.output_trap = RedirectorOutputTrap(
+                            out_callback=self.write,
+                            err_callback=self.write,
                                             )
         # Capture and release the outputs, to make sure all the
         # shadow variables are set

IPython/kernel/core/redirector_output_trap.py

@@ -59,7 +59,10 b' class RedirectorOutputTrap(OutputTrap):'
             redirectors.
         """
         OutputTrap.unset(self)
+        # Flush the redirectors before stopping them
+        self.on_out_write('')
         self.err_redirector.stop()
+        self.on_err_write('')
         self.out_redirector.stop()
 
 
@@ -69,11 +72,22 b' class RedirectorOutputTrap(OutputTrap):'
     def on_out_write(self, string):
         """ Callback called when there is some Python output on stdout.
         """
-        self.out_callback(self.out_redirector.getvalue() + string)
+        try:
+            self.out_callback(self.out_redirector.getvalue() + string)
+        except:
+            # If tracebacks are happening and we can't see them, it is
+            # quasy impossible to debug
+            self.unset()
+            raise
 
     def on_err_write(self, string):
         """ Callback called when there is some Python output on stderr.
         """
-        self.err_callback(self.err_redirector.getvalue() + string)
-
+        try:
+            self.err_callback(self.err_redirector.getvalue() + string)
+        except:
+            # If tracebacks are happening and we can't see them, it is
+            # quasy impossible to debug
+            self.unset()
+            raise