{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# 与操作系统进行交互：os 模块"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "`os` 模块提供了对系统文件进行操作的方法："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "import os"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 文件路径操作"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "- `os.remove(path)` 或 `os.unlink(path)` ：删除指定路径的文件。路径可以是全名，也可以是当前工作目录下的路径。\n",
    "- `os.removedirs`：删除文件，并删除中间路径中的空文件夹\n",
    "- `os.chdir(path)`：将当前工作目录改变为指定的路径\n",
    "- `os.getcwd()`：返回当前的工作目录\n",
    "- `os.curdir`：表示当前目录的符号\n",
    "- `os.rename(old, new)`：重命名文件\n",
    "- `os.renames(old, new)`：重命名文件，如果中间路径的文件夹不存在，则创建文件夹\n",
    "- `os.listdir(path)`：返回给定目录下的所有文件夹和文件名，不包括 `'.'` 和 `'..'` 以及子文件夹下的目录。（`'.'` 和 `'..'` 分别指当前目录和父目录）\n",
    "- `os.mkdir(name)`：产生新文件夹\n",
    "- `os.makedirs(name)`：产生新文件夹，如果中间路径的文件夹不存在，则创建文件夹\n",
    "\n",
    "当前目录："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'/home/lijin/notes-python/05. advanced python'"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "os.getcwd()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "当前目录的符号："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'.'"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "os.curdir"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "当前目录下的文件："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['05.01 overview of the sys module.ipynb',\n",
       " '05.05 datetime.ipynb',\n",
       " '05.13 decorator usage.ipynb',\n",
       " '.ipynb_checkpoints',\n",
       " '05.03 comma separated values.ipynb',\n",
       " '05.02 interacting with the OS - os.ipynb',\n",
       " '05.10 generators.ipynb',\n",
       " '05.15 scope.ipynb',\n",
       " '05.12 decorators.ipynb',\n",
       " '05.09 iterators.ipynb',\n",
       " 'my_database.sqlite',\n",
       " '05.11 context managers and the with statement.ipynb',\n",
       " '05.16 dynamic code execution.ipynb',\n",
       " '05.14 the operator functools itertools toolz fn funcy module.ipynb',\n",
       " '05.04 regular expression.ipynb',\n",
       " '05.07 object-relational mappers.ipynb',\n",
       " '05.08 functions.ipynb',\n",
       " '05.06 sql databases.ipynb']"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "os.listdir(os.curdir)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "产生文件："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "True\n"
     ]
    }
   ],
   "source": [
    "f = open(\"test.file\", \"w\")\n",
    "f.close()\n",
    "\n",
    "print \"test.file\" in os.listdir(os.curdir)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "重命名文件："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "False\n",
      "True\n"
     ]
    }
   ],
   "source": [
    "os.rename(\"test.file\", \"test.new.file\")\n",
    "\n",
    "print \"test.file\" in os.listdir(os.curdir)\n",
    "print \"test.new.file\" in os.listdir(os.curdir)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "删除文件："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "os.remove(\"test.new.file\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "collapsed": true
   },
   "source": [
    "## 系统常量"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "当前操作系统的换行符："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'\\n'"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# windows 为 \\r\\n\n",
    "os.linesep"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "当前操作系统的路径分隔符："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'/'"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "os.sep"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "当前操作系统的环境变量中的分隔符（`';'` 或 `':'`）："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "':'"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "os.pathsep"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 其他"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "`os.environ` 是一个存储所有环境变量的值的字典，可以修改。"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'lijin'"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "os.environ[\"USER\"]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "`os.urandom(len)` 返回指定长度的随机字节。"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## os.path 模块"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "不同的操作系统使用不同的路径规范，这样当我们在不同的操作系统下进行操作时，可能会带来一定的麻烦，而 `os.path` 模块则帮我们解决了这个问题。"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "import os.path"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 测试"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "- `os.path.isfile(path)` ：检测一个路径是否为普通文件\n",
    "- `os.path.isdir(path)`：检测一个路径是否为文件夹\n",
    "- `os.path.exists(path)`：检测路径是否存在\n",
    "- `os.path.isabs(path)`：检测路径是否为绝对路径"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### split 和 join"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "- `os.path.split(path)`：拆分一个路径为 `(head, tail)` 两部分\n",
    "- `os.path.join(a, *p)`：使用系统的路径分隔符，将各个部分合成一个路径"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 其他"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "- `os.path.abspath()`：返回路径的绝对路径\n",
    "- `os.path.dirname(path)`：返回路径中的文件夹部分\n",
    "- `os.path.basename(path)`：返回路径中的文件部分\n",
    "- `os.path.splitext(path)`：将路径与扩展名分开\n",
    "- `os.path.expanduser(path)`：展开 `'~'` 和 `'~user'`"
   ]
  }
 ],
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