>>> f = open('/tmp/foo.txt', 'rb+')
>>> f.write(b'0123456789abcdef')
16
>>> f.seek(5)     # 移动到文件的第六个字节
5
>>> f.read(1)
b'5'
>>> f.seek(-3, 2) # 移动到文件的倒数第三字节
13
>>> f.read(1)
b'd'

>>> with open('/tmp/foo.txt', 'r') as f:
...     read_data = f.read()
>>> f.closed
True

f = open("forwrite.txt", "w+",encoding='utf-8')
f.write("7777777 6666")  # 此时文件对象在最后一行，如果读取，将读不到数据
s=f.tell()     # 返回文件对象当前位置
f.seek(0,0)    # 移动文件对象至第一个字符
str=f.read()
print(s,str,len(str))

with open('test.txt', 'r+') as f:
    # 检测文件对象是否连接到终端设备
    print(f.isatty())
    # 截取两个字节
    f.truncate(2)
    print(f.read())

pickle.dump(obj, file, [,protocol])
x = pickle.load(file)

#!/usr/bin/python3
import pickle

# 使用pickle模块将数据对象保存到文件
data1 = {'a': [1, 2.0, 3, 4+6j],
         'b': ('string', u'Unicode string'),
         'c': None}

selfref_list = [1, 2, 3]
selfref_list.append(selfref_list)

output = open('data.pkl', 'wb')

# Pickle dictionary using protocol 0.
pickle.dump(data1, output)

# Pickle the list using the highest protocol available.
pickle.dump(selfref_list, output, -1)

output.close()

#!/usr/bin/python3
import pprint, pickle

#使用pickle模块从文件中重构python对象
pkl_file = open('data.pkl', 'rb')

data1 = pickle.load(pkl_file)
pprint.pprint(data1)

data2 = pickle.load(pkl_file)
pprint.pprint(data2)

pkl_file.close()