Python教程-常用标准库sys

# test.py
import sys
for index, arg in enumerate(sys.argv):    print("第%d个参数是：%s" % (index, arg))

第0个参数是：test.py第1个参数是：1第2个参数是：2第3个参数是：3第4个参数是：4

>>> a = "I like Python!">>> sys.getrefcount(a)2>>> b = a>>> sys.getrefcount(a)3>>> c = a>>> sys.getrefcount(a)4>>> del c>>> sys.getrefcount(a)3>>> del b>>> sys.getrefcount(a)2>>> sys.getrefcount(1)902>>> sys.getrefcount("a")36>>> sys.getrefcount(True)581>>> sys.getrefcount(None)6918

>>> import sys>>> sys.modules{'builtins': <module 'builtins' (built-in)>, 'sys': <module 'sys' (built-in)>, '_frozen_importlib': <module 'importlib._bootstrap' (frozen)>, '_imp': <module '_imp' (built-in)>, '_warnings': <module '_warnings' (built-in)>, '_thread': .......截取部分>>> sys.modules.keys()dict_keys(['builtins', 'sys', '_frozen_importlib', '_imp', '_warnings', '_thread', '_weakref', '_frozen_importlib_external', '_io', 'marshal', 'nt', 'winreg', 'zipimport', 'encodings', 'codecs', '_codecs', 'encodings.aliases', ...截取部分>>> sys.modules.values()dict_values([<module 'builtins' (built-in)>, <module 'sys' (built-in)>, <module 'importlib._bootstrap' (frozen)>, <module '_imp' (built-in)>, <module '_warnings' (built-in)>, <module '_thread' (built-in)>, <module '_weakref' module 'urllib.parse' from 'C:\\Python36\\lib\\urllib\\parse.py'>]).......截取部分>>> sys.modules['sys']<module 'sys' (built-in)>

import sys
def find_module(module):    if module in sys.builtin_module_names:        print(module, " 内置于=> ", "__builtin__")    else:        print(module, "模块位于=> ", __import__(module).__file__)

find_module('os')find_module('sys')find_module('time')find_module('zlib')find_module('string')
#----------运行结果：os 模块位于=>  C:\Python36\lib\os.pysys  内置于=>  __builtin__time  内置于=>  __builtin__zlib  内置于=>  __builtin__string 模块位于=>  C:\Python36\lib\string.py

>>> sys.path['', 'C:\\Python36\\Lib\\idlelib', 'C:\\Python36\\python36.zip', 'C:\\Python36\\DLLs', 'C:\\Python36\\lib', 'C:\\Python36', 'C:\\Python36\\lib\\site-packages']

>>> import sys>>> s = sys.stdin.read()        # 使用ctrl+d结束输入i like pythonend
>>> s'i like python\nend\n\n\n\n'>>> sys.stdout.write(s)i like pythonend
21

sys.stdout.write('hello'+'\n') print('hello')

s = input('Please input something！')
print('Please input something！',)  # 逗号表示不换行s = sys.stdin.readline()[:-1]  # -1 可以抛弃输入流中的'\n' 换行符，自己琢磨一下为什么。

f_handler = open('out.log', 'w') sys.stdout = f_handler print('hello')# 你无法在屏幕上看到“hello”# 因为它被写到out.log文件里了

__console__ = sys.stdout    # 保存控制台# redirection start #       # 去干点别的，比如写到文件里... # redirection end           # 干完别的了，恢复原来的控制台sys.stdout = __console__

import sysimport timedef bar(num, total):    rate = num / total    rate_num = int(rate * 100)    r = '\r[%s%s]%d%%' % ("="*num, " "*(100-num), rate_num, )    sys.stdout.write(r)    sys.stdout.flush()if __name__ == '__main__':    for i in range(0, 101):        time.sleep(0.1)        bar(i, 100)