store exit code in user_ns['_exit_code']

_exit_code is an equivalent to `$?` in bash.
It always has the most recent exit value of a shell.system
subprocess.

IPython/core/interactiveshell.py

@@ -1890,8 +1890,10 b' class InteractiveShell(SingletonConfigurable, Magic):'
             # if they really want a background process.
             raise OSError("Background processes not supported.")
         
-        # don't return the result, always return None
-        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
@@ -1901,8 +1903,10 b' class InteractiveShell(SingletonConfigurable, Magic):'
         cmd : str
           Command to execute.
         """
-        # don't return the result, always return None
-        os.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'] = os.system(self.var_expand(cmd, depth=2))
     
     # use piped system by default, because it is better behaved
     system = system_piped

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):