add THEFUCK_HISTORY_LIMIT, my machine is so slow

README.md

@@ -302,7 +302,8 @@ Or via environment variables:
 * `THEFUCK_NO_COLORS` – disable colored output, `true/false`;
 * `THEFUCK_PRIORITY` – priority of the rules, like `no_command=9999:apt_get=100`,
 rule with lower `priority` will be matched first;
-* `THEFUCK_DEBUG` – enables debug output, `true/false`.
+* `THEFUCK_DEBUG` – enables debug output, `true/false`;
+* `THEFUCK_HISTORY_LIMIT` – how many history commands will be scanned, like `2000`.
 
 For example:
 

thefuck/conf.py

@@ -24,7 +24,8 @@ ENV_TO_ATTR = {'THEFUCK_RULES': 'rules',
                'THEFUCK_REQUIRE_CONFIRMATION': 'require_confirmation',
                'THEFUCK_NO_COLORS': 'no_colors',
                'THEFUCK_PRIORITY': 'priority',
-               'THEFUCK_DEBUG': 'debug'}
+               'THEFUCK_DEBUG': 'debug',
+               'THEFUCK_HISTORY_LIMIT': 'history_limit'}
 
 SETTINGS_HEADER = u"""# ~/.thefuck/settings.py: The Fuck settings file
 #
@@ -125,3 +126,4 @@ class Settings(dict):
 
 
 settings = Settings(DEFAULT_SETTINGS)
+settings.init()

thefuck/shells.py

@@ -10,6 +10,7 @@ from time import time
 import io
 import os
 from .utils import DEVNULL, memoize, cache
+from .conf import settings
 
 
 class Generic(object):
@@ -59,10 +60,16 @@ class Generic(object):
 
     def get_history(self):
         """Returns list of history entries."""
+        tail_num = settings.get("history_limit", None)
         history_file_name = self._get_history_file_name()
         if os.path.isfile(history_file_name):
-            with io.open(history_file_name, 'r',
-                         encoding='utf-8', errors='ignore') as history:
+            if tail_num is not None:
+                _, f = os.popen2("tail -n {} {}".format(tail_num, history_file_name))
+                _.close()
+            else:
+                f = io.open(history_file_name, 'r',
+                         encoding='utf-8', errors='ignore')
+            with f as history:
                 for line in history:
                     prepared = self._script_from_history(line)\
                                    .strip()