03 Python 文件系统访问权限函数类与面向对象自定义模块

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990487026 2015-12-13 15:46:59 博主文章分类：Linux 开发 ©著作权

文章标签 03 Python 文件系统访问权限 文章分类 Python 后端开发

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文件系统和文件

创建一个文件

readline()与readlines()区别

查看指针指向位置

w+写入模式

访问权限

文件的权限修改

修改文件的属主属组

import pickle 将内存持久存入文件中

函数

匿名函数 lambda

filter过滤器

映射器

函数闭包

生成器遍历

生成器泰列表

yield与生成器

生成器自身是可以迭代的

装饰器

带有参数的装饰器

python类与面向对象

我的第一个python类

方法构造器__init__

python父类的继承

谁是谁的子类判断！

自定义模块路径

制作模块包

python 异常

文件系统和文件

In [20]: f1=open("/etc/passwd" ,"r") 打开一个文件

In [21]: f1.next()

Out[21]:'root:x:0:0:root:/root:/bin/bash\n'

In [22]: f1.next()

Out[22]: 'bin:x:1:1:bin:/bin:/sbin/nologin\n'

In [23]: f1.close() 关闭

In [24]: f1.next() 会报错

readline()与readlines()区别

In [25]:f1=open("/etc/passwd" ,"r")

In [26]: f1.readline()

Out[26]:'root:x:0:0:root:/root:/bin/bash\n'

In [27]: f1.readlines() 以列表的形式返回元素

Out[27]:

['bin:x:1:1:bin:/bin:/sbin/nologin\n',

'daemon:x:2:2:daemon:/sbin:/sbin/nologin\n',

'adm:x:3:4:adm:/var/adm:/sbin/nologin\n',

………………………………

In [64]: f1.seek(0) 恢复指针到0

In [65]: f1.tell() 查看指针指向位置，然后指向下一个

Out[65]: 0

In [66]: f1.read(10)

Out[66]: 'root:x:0:0'

In [67]: f1.read(20)

Out[67]:':root:/root:/bin/bash\nbin:x:1:1

In [70]: f1.tell()

Out[70]: 210查看指针指向位置，然后指向下一个

In [71]: f1.next()

Out[71]: 'sync\n'

In [72]: f1.next()

Out[72]:'shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown\n'

In [76]: f1.name

Out[76]: '/etc/passwd'

修改文件

f1=open('/etc/passwd',"r+") r+ 读写模式

w+写入模式必须要有换行符\n 否则会清空文件内容

In [8]: f1.tell()查看指针指向位置

Out[8]: 0

In [14]: f1.seek(0,2)

In [15]: f1.tell()查看指针指向位置

Out[15]: 1887

f1.write("a new line\n") 写入命令

In [1]: import os

In [2]: l2 = os.listdir("/etc")

In [3]: print l2

['bashrc', 'chkconfig.d','xdg', 'pm', ……………………

In [4]: l3=[i for i in os.listdir("/etc")]

In [5]: print l3

['bashrc', 'chkconfig.d','xdg………………………………

In [6]: l3=[i+'haha\n' for i in os.listdir("/etc")]

In [7]: print l3

['bashrchaha\n', 'chkconfig.dhaha\n', 'xdghaha\n', '

创建一个文件，把l3写进去

In [8]:f4=open('/tmp/test','w+')

In [9]: f4.writelines(l3)

In [10]: f4.flush() 把内存的内容同步到磁盘 OK

[root@localhost ~]# cat/tmp/test

bashrchaha

chkconfig.dhaha

xdghaha

pmhaha

DIR_COLORS.256colorh

In [17]: f4.seek(0)

In [18]: f4.readlines()

Out[18]:

['bashrchaha\n',

'chkconfig.dhaha\n',

'xdghaha\n',

'pmhaha\n',

.truncate截取到此，之后的文件内容都不要

In [19]: f4.seek(0)

In [20]: f4.readline()

Out[20]: 'bashrchaha\n'

In [21]: f4.readline()

Out[21]: 'chkconfig.dhaha\n'

In [22]: f4.readline()

Out[22]: 'xdghaha\n'

In [23]: f4.readline()

Out[23]: 'pmhaha\n'

In [24]:f4.truncate(f4.tell())

In [25]: f4.seek(0)

你看看

In [26]: f4.readlines()

Out[26]: ['bashrchaha\n','chkconfig.dhaha\n', 'xdghaha\n', 'pmhaha\n']

In[28]: f4.mode 获取当前文件的打开模式

Out[28]:'w+'

In[30]: f4.closed 查看文件是否关闭

Out[30]:True

创建目录的接口

In [31]:os.mkdir("/tmp/haha")

获取当前操作的路径

In [33]: os.getcwd()

Out[33]: '/root'

更改操作路径

In [34]:os.chdir("/tmp")

In [35]: os.getcwd()

Out[35]: '/tmp'

获取文件 1的状态

In [36]:os.stat("/tmp/haha/1")

Out[36]:posix.stat_result(st_mode=33188, st_ino=1441801, st_dev=64768L, st_nlink=1,st_uid=0, st_gid=0, st_size=0, st_atime=1431609591, st_mtime=1431609591,st_ctime=1431609591)

递归生成目录

In [37]:os.makedirs("/e/r/t")

创建快捷方式

In [38]: os.getcwd()

Out[38]: '/tmp'

In [39]:os.symlink("jj","kk")

你看看

-rw-r--r-- 1 root root 0 May 14 21:34 jj

lrwxrwxrwx 1 root root 2 May 14 21:35 kk -> jj

g1=os.walk("/etc")

In [41]: g1.next() 遍历出来

Out[41]:

('/etc', 顶级目录

['chkconfig.d',

'xdg',

'pm',

'vsftpd',

访问权限

In [44]:os.access("jj",0) 0就是root

Out[44]: True

In [45]:os.access("jj",20)

Out[45]: False

文件的权限修改

In [47]:os.chmod("jj",0677)

你看看

-rw-r----- 1 root root 0 May 14 21:34 jj

-rw-rwxrwx 1 root root 0 May 14 21:34 jj

修改文件的属主属组

[root@localhost tmp]# useraddhaha

[root@localhost tmp]# id haha

uid=503(haha) gid=503(haha)groups=503(haha)

os.chown("jj",503,503)

-rw-rwxrwx 1 root root 0 May 14 21:34 jj

-rw-rwxrwx 1 haha haha 0 May 14 21:34 jj

import os.path

dir1 =os.path.dirname("/etc/sysconfig/network-scripts/")

In [53]: print dir1

/etc/sysconfig/network-scripts

#!/usr/local/python27/bin/python2.7

import os

import os.path

filename='/home/a.txt'

if os.path.isfile(filename):

f1=open(filename,'a+')

while True:

line = raw_input("enter ")

if line =='q' or line =='quit' :

break

f1.write(line+'\n')

f1.close()

import pickle 将内存持久存入文件中

函数

返回这个函数

函数变量，本地没有去全局（global）找

In [1]: def f1():

...: x=6

...: def f2():

...: y="welcome"

...: print x,y

...: return f2

...:

In [2]: a1=f1()

In [4]: type (a1)

Out[4]: function

In [9]: a1()

6 welcome 6 闭包的记忆效应

函数举例

In [10]: def f2(x,y):

....: print x+y

In [11]: f2(4,8)

In [13]:f2("LCL"," linux")

LCL linux

默认是元组

默认是字典

混合

分解赋值

元素个数不匹配会出错

自动匹配

匿名函数 lambda

In [14]: lambda x,y:x+y

Out[14]: <function__main__.<lambda>>

In [15]: f2=lambda x,y:x+y

In [16]: f2(3,9)

Out[16]: 12

引用

In [17]: l3 = [(lambdax:x*3),(lambda y:y*5)]

In [18]: for i in l3 :

....: print i(3)

....:

函数式编程

filter过滤器

In [19]:l1=[4,8,6,4,5,6,7,8,9,23,9]

In [20]: def fun1(x):

....: if x > 4:

....: return True

....: else:

....: return False

In [22]: filter(fun1 ,l1)

Out[22]: [8, 6, 5, 6, 7, 8,9, 23, 9]

map

这个功能略吊

In [25]: l1=[ 2, 3, 4, 5, 6,7, 8, 9, 10, 11]

In [26]: l2=[4, 5, 6, 7, 8,9, 10, 11, 12, 13]

In [27]: map(None ,l2,l1)

Out[27]:

[(4, 2),

(5, 3),

(6, 4),

(7, 5),

(8, 6),

(9, 7),

(10, 8),

(11, 9),

(12, 10),

(13, 11)]

In [29]: def f3(x):

return x*3

In [30]: map (f3,l1)

Out[30]: [6, 9, 12, 15, 18,21, 24, 27, 30, 33]

reduce函数

In [32]: def f5(x,y):

....: return x +y

In [33]: reduce (f5,l2)

Out[33]: 85

In [34]: reduce (f5,l2,50)

Out[34]: 135

函数闭包

In [35]: def f1(x):

....: def f2(y):

....: return x**y

....: return f2

....:

In [36]: a1=f1(4)

In [37]: a1(2)

Out[37]: 16

深刻示例

In [51]: def f1(x,y):

def f2(m,n):

print "old (%d,%d),new(%d,%d)" %(x, y ,x+m ,y+n)

return f2

....:

In [52]: a1=f1(10,10)

In [53]: a1(2,7)

old (10,10),new (12,17)

生成器à遍历a**2 for a in range(1,11)

In [58]: for i in (a**2 for ain range(1,11)):

print i,

....:

1 4 9 16 25 36 49 64 81 100

生成器à转列表

In [59]: list(i**3 for i inrange(1,11))

Out[59]: [1, 8, 27, 64, 125,216, 343, 512, 729, 1000]

yield与生成器

In [60]: def genNum(x):

....: y=0

....: while y<=x :

....: yield y

....: y+=1

In [61]: g1=genNum(13)

In [62]: g1.next()

Out[62]: 0

In [63]: g1.next()

Out[63]: 1

生成器自身是可以迭代的

In [64]: def genNum(x):

....: i=1

....: while i<=x:

....: yield i**2

....: i+=1

In [70]: g1=genNum(6)

In [71]: for i in g1 :

print i,

....:

1 4 9 16 25 36

装饰器

带有参数的装饰器

递归

In [72]: def f1(x):

....: if x<=1:

....: return 1

....: else:

....: return x*f1(x-1)

....:

In [73]: f1(4)

Out[73]: 24

In [74]: f1(3)

Out[74]: 6

In [75]: f1(6)

Out[75]: 720

练习：实现费伯纳多数列

python类与面向对象

我的第一个python类

In [77]: class FirstClass():

....: data= "welcome my first class"

....: def printdata(self):

....: print self.data

In [79]: ins1= FirstClass() 实例化类

In [81]: ins1.data

Out[81]: 'welcome my firstclass'

In [82]: ins1.printdata()

welcome my first class

我的第二个

In [86]: class Second():

data= "Second"

def set(self,x):

self.str=x

def print1(self):

print self.str

....:

In [88]: a=Second()

In [89]: a.data

Out[89]: 'Second'

In [90]:a.set("haha")

In [91]: a.print1() 关键字不能让那个当类名

haha

方法构造器__init__

In [101]: class Myclass():

data= "hahahah 1 line"

def __init__(self,x):

self.str1=x

In [102]:a1=Myclass("LCL")

In [103]: a1.data

Out[103]: 'hahahah 1 line'

In [105]: a1.str1

Out[105]: 'LCL'

python父类的继承

In [106]: classPclass(object):

.....: gender="M"

.....: def __init__(self,who):

.....: self.name=who

.....:

In [107]: class Cclass(Pclass):

.....: def display (self):

.....: print self.gender,self.name

.....:

In [108]:a=Cclass("haha")

In [109]: a.display()

M haha

In [111]: a.gender

Out[111]: 'M'

In [112]: a.name

Out[112]: 'haha'

In [113]: dir(a) dir查看实例

Out[113]:

['__class__',

'__delattr__',

'__dict__',

'__doc__',

'__format__',

'__getattribute__',

'__hash__',

'__init__',

'__module__',

'__new__',

'__reduce__',

'__reduce_ex__',

'__repr__',

'__setattr__',

'__sizeof__',

'__str__',

'__subclasshook__',

'__weakref__',

'display',

'gender',

'name']

谁是谁的子类判断！

In [115]: issubclass(Pclass,Cclass)

Out[115]: False

In [116]:issubclass(Cclass,Pclass)

Out[116]: True

In [117]:issubclass(Cclass,object)

Out[117]: True

这是不是你的实例

In [118]:isinstance(a,Cclass)

Out[118]: True

显示python默认的所有标准库模块

help("modules")

In [3]: import sys

In[5]: print sys.path

['','/usr/local/python27/bin', '/usr/local/python27/lib/python27.zip','/usr/local/python27/lib/python2.7', '/usr/local/python27/lib/python2.7/plat-linux2','/usr/local/python27/lib/python2.7/lib-tk','/usr/local/python27/lib/python2.7/lib-old','/usr/local/python27/lib/python2.7/lib-dynload','/usr/local/python27/lib/python2.7/site-packages', '/usr/local/python27/lib/python2.7/site-packages/IPython/extensions']

依次在以上路径寻找要导入的库文件

自定义模块路径

我自己/tmp下面写了一个py

#!/usr/bin/python27

x=30

def printInfo():

print x + 30

class MyClass():

data = "hello world!"

def __init__(self,who):

self.name=who

def printName(self):