From 6acab007f605f2f58c2ab5aa901d200184f43e90 Mon Sep 17 00:00:00 2001
From: XiongNeng <yidao620@gmail.com>
Date: Wed, 24 Sep 2014 00:20:03 +0800
Subject: [PATCH] =?UTF-8?q?5.12=E5=B0=8F=E8=8A=82=E5=AE=8C=E6=88=90?=
MIME-Version: 1.0
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---
 cookbook/c05/p12_file_existence.py            | 27 ++++++++
 .../p12_test_for_the_existence_of_file.rst    | 66 ++++++++++++++++++-
 2 files changed, 90 insertions(+), 3 deletions(-)
 create mode 100644 cookbook/c05/p12_file_existence.py

diff --git a/cookbook/c05/p12_file_existence.py b/cookbook/c05/p12_file_existence.py
new file mode 100644
index 0000000..9f9b48d
--- /dev/null
+++ b/cookbook/c05/p12_file_existence.py
@@ -0,0 +1,27 @@
+#!/usr/bin/env python
+# -*- encoding: utf-8 -*-
+"""
+Topic: 测试文件或目录是否存在
+Desc : 
+"""
+import os
+import time
+
+
+def file_existence():
+    print(os.path.exists('/etc/passwd'))
+    print(os.path.exists('/tmp/spam'))
+
+    print(os.path.isfile('/etc/passwd'))
+    print(os.path.isdir('/etc/passwd'))
+    print(os.path.islink('/usr/local/bin/python3'))
+    print(os.path.realpath('/usr/local/bin/python3'))
+
+    print(os.path.getsize('/etc/passwd'))
+    print(os.path.getmtime('/etc/passwd'))
+    print(time.ctime(os.path.getmtime('/etc/passwd')))
+
+
+if __name__ == '__main__':
+    file_existence()
+
diff --git a/source/c05/p12_test_for_the_existence_of_file.rst b/source/c05/p12_test_for_the_existence_of_file.rst
index 75bb7ae..f0329bf 100644
--- a/source/c05/p12_test_for_the_existence_of_file.rst
+++ b/source/c05/p12_test_for_the_existence_of_file.rst
@@ -5,14 +5,74 @@
 ----------
 问题
 ----------
-todo...
+你想测试一个文件或目录是否存在。
+
+|
 
 ----------
 解决方案
 ----------
-todo...
+使用 ``os.path`` 模块来测试一个文件或目录是否存在。比如：
+
+.. code-block:: python
+
+    >>> import os
+    >>> os.path.exists('/etc/passwd')
+    True
+    >>> os.path.exists('/tmp/spam')
+    False
+    >>>
+
+你还能进一步测试这个文件时什么类型的。
+在下面这些测试中，如果测试的文件不存在的时候，结果都会返回False：
+
+.. code-block:: python
+
+    >>> # Is a regular file
+    >>> os.path.isfile('/etc/passwd')
+    True
+
+    >>> # Is a directory
+    >>> os.path.isdir('/etc/passwd')
+    False
+
+    >>> # Is a symbolic link
+    >>> os.path.islink('/usr/local/bin/python3')
+    True
+
+    >>> # Get the file linked to
+    >>> os.path.realpath('/usr/local/bin/python3')
+    '/usr/local/bin/python3.3'
+    >>>
+
+如果你还想获取元数据(比如文件大小或者是修改日期)，也可以使用 ``os.path`` 模块来解决：
+
+.. code-block:: python
+
+    >>> os.path.getsize('/etc/passwd')
+    3669
+    >>> os.path.getmtime('/etc/passwd')
+    1272478234.0
+    >>> import time
+    >>> time.ctime(os.path.getmtime('/etc/passwd'))
+    'Wed Apr 28 13:10:34 2010'
+    >>>
+
+|
 
 ----------
 讨论
 ----------
-todo...
\ No newline at end of file
+使用 ``os.path`` 来进行文件测试是很简单的。
+在写这些脚本时，可能唯一需要注意的就是你需要考虑文件权限的问题，特别是在获取元数据时候。比如：
+
+.. code-block:: python
+
+    >>> os.path.getsize('/Users/guido/Desktop/foo.txt')
+    Traceback (most recent call last):
+        File "<stdin>", line 1, in <module>
+        File "/usr/local/lib/python3.3/genericpath.py", line 49, in getsize
+            return os.stat(filename).st_size
+    PermissionError: [Errno 13] Permission denied: '/Users/guido/Desktop/foo.txt'
+    >>>
+