Merge PR #459 (issue 297)

closes gh-110
closes gh-459

IPython/core/interactiveshell.py

@@ -1872,22 +1872,44 b' class InteractiveShell(SingletonConfigurable, Magic):'
     # Things related to the running of system commands
     #-------------------------------------------------------------------------
 
-    def system(self, cmd):
-        """Call the given cmd in a subprocess.
+    def system_piped(self, cmd):
+        """Call the given cmd in a subprocess, piping stdout/err
 
         Parameters
         ----------
         cmd : str
-          Command to execute (can not end in '&', as bacground processes are
-          not supported.
+          Command to execute (can not end in '&', as background processes are
+          not supported.  Should not be a command that expects input
+          other than simple text.
         """
+        if cmd.rstrip().endswith('&'):
+            # this is *far* from a rigorous test
         # We do not support backgrounding processes because we either use
         # pexpect or pipes to read from.  Users can always just call
-        # os.system() if they really want a background process.
-        if cmd.endswith('&'):
+            # os.system() or use ip.system=ip.system_raw
+            # if they really want a background process.
             raise OSError("Background processes not supported.")
 
-        return system(self.var_expand(cmd, depth=2))
+        # we explicitly do NOT return the subprocess status code, because
+        # a non-None value would trigger :func:`sys.displayhook` calls.
+        # Instead, we store the exit_code in user_ns.
+        self.user_ns['_exit_code'] = system(self.var_expand(cmd, depth=2))
+    
+    def system_raw(self, cmd):
+        """Call the given cmd in a subprocess using os.system
+        
+        Parameters
+        ----------
+        cmd : str
+          Command to execute.
+        """
+        # We explicitly do NOT return the subprocess status code, because
+        # a non-None value would trigger :func:`sys.displayhook` calls.
+        # Instead, we store the exit_code in user_ns.
+        self.user_ns['_exit_code'] = os.system(self.var_expand(cmd, depth=2))
+    
+    # use piped system by default, because it is better behaved
+    system = system_piped
 
     def getoutput(self, cmd, split=True):
         """Get output (possibly including stderr) from a subprocess.
@@ -1905,7 +1927,8 b' class InteractiveShell(SingletonConfigurable, Magic):'
           manipulation of line-based output.  You can use '?' on them for
           details.
           """
-        if cmd.endswith('&'):
+        if cmd.rstrip().endswith('&'):
+            # this is *far* from a rigorous test
             raise OSError("Background processes not supported.")
         out = getoutput(self.var_expand(cmd, depth=2))
         if split:
@@ -2172,7 +2195,9 b' class InteractiveShell(SingletonConfigurable, Magic):'
             prefilter_failed = False
             if len(cell.splitlines()) == 1:
                 try:
-                    cell = self.prefilter_manager.prefilter_line(cell)
+                    # use prefilter_lines to handle trailing newlines
+                    # restore trailing newline for ast.parse
+                    cell = self.prefilter_manager.prefilter_lines(cell) + '\n'
                 except AliasError as e:
                     error(e)
                     prefilter_failed=True

IPython/core/tests/test_interactiveshell.py

@@ -107,3 +107,10 b' class InteractiveShellTestCase(unittest.TestCase):'
         io.stderr = save_err
         self.assertEquals(err.split(':')[0], 'ERROR')
 
+    def test_trailing_newline(self):
+        """test that running !(command) does not raise a SyntaxError"""
+        ip = get_ipython()
+        ip.run_cell('!(true)\n', False)
+        ip.run_cell('!(true)\n\n\n', False)
+
+

IPython/frontend/terminal/interactiveshell.py

@@ -86,6 +86,12 b' class TerminalInteractiveShell(InteractiveShell):'
             config=config, ipython_dir=ipython_dir, user_ns=user_ns,
             user_global_ns=user_global_ns, custom_exceptions=custom_exceptions
         )
+        # use os.system instead of utils.process.system by default, except on Windows
+        if os.name == 'nt':
+            self.system = self.system_piped
+        else:
+            self.system = self.system_raw
+        
         self.init_term_title()
         self.init_usage(usage)
         self.init_banner(banner1, banner2, display_banner)

IPython/utils/_process_posix.py

@@ -130,9 +130,7 b' class ProcessHandler(object):'
 
         Returns
         -------
-        None : we explicitly do NOT return the subprocess status code, as this
-        utility is meant to be used extensively in IPython, where any return
-        value would trigger :func:`sys.displayhook` calls.
+        int : child's exitstatus
         """
         pcmd = self._make_cmd(cmd)
         # Patterns to match on the output, for pexpect.  We read input and
@@ -181,6 +179,7 b' class ProcessHandler(object):'
             finally:
                 # Ensure the subprocess really is terminated
                 child.terminate(force=True)
+        return child.exitstatus
 
     def _make_cmd(self, cmd):
         return '%s -c "%s"' % (self.sh, cmd)

IPython/utils/_process_win32.py

@@ -96,6 +96,9 b' def _system_body(p):'
         line = line.decode(enc, 'replace')
         print(line, file=sys.stderr)
 
+    # Wait to finish for returncode
+    return p.wait()
+
 
 def system(cmd):
     """Win32 version of os.system() that works with network shares.
@@ -116,7 +119,7 b' def system(cmd):'
     with AvoidUNCPath() as path:
         if path is not None:
             cmd = '"pushd %s &&"%s' % (path, cmd)
-        process_handler(cmd, _system_body)
+        return process_handler(cmd, _system_body)
 
 
 def getoutput(cmd):