Python基础学习之标准库sys总结

本篇文章给大家带来了关于python的相关知识，其中主要介绍了标准库sys的相关问题，Python的sys模块提供访问由解释器使用或维护的变量的接口，并提供了一些函数用来和解释器进行交互，操控Python的运行时环境，希望对大家有帮助。

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sys作用

Python的sys模块提供访问由解释器使用或维护的变量的接口，并提供了一些函数用来和解释器进行交互，操控Python的运行时环境。

>>> import sys

常用变量

sys.version

返回Python解释器版本号；用于某程序需要用指定版本号运行

>>> import sys
>>> sys.version
3.8.5 (tags/v3.8.5:580fbb0, Jul 20 2020, 15:57:54) [MSC v.1924 64 bit (AMD64)]

sys.maxsize

表示操作系统承载的最大int值

>>> import sys
>>> sys.maxsize
9223372036854775807

sys.maxunicode

给出最大Unicode代码点值的整数，即1114111（十六进制0x10FFFF）。

>>> import sys
>>> sys.maxunicode
1114111

sys.path

当前脚本的path环境变量，如果没有python就找到

>>> import sys
>>> sys.path
['', 'D:\\Python3.8\\python38.zip', 'D:\\Python3.8\\DLLs', 'D:\\Python3.8\\lib', 'D:\\Python3.8', 'D:\\Python3.8\\lib\\site-packages']

sys.platform

返回操作系统平台名称，在编写跨平台应用时很有用

>>> import sys>>> sys.platform
win32

sys.argv

将python脚本运行时的脚本名以及参数作为一个list，并输出。实现从程序外部像程序内容传递参数

import sysprint(sys.argv)

E:\Python> python 2.py hello python['2.py', 'hello', 'python']

sys.executable

一个字符串，给出Python解释器的可执行二进制文件的绝对路径。如果Python无法检索其可执行文件的真实路径，sys.executable则将为空字符串或None。

>>> import sys
>>> sys.executable
'D:\\Python3.8\\python.exe'

sys.byteorder

本地字节顺序的指示符——在大端序（最高有效位优先）操作系统上值为 ‘big’ ，在小端序（最低有效位优先）操作系统上为 'little

>>> import sys>>> sys.byteorder'little'

sys.version_info

包含版本号的五个组件的元组：major，minor， micro，releaselevel和serial。

>>> import sys
>>> sys.version_info
sys.version_info(major=3, minor=7, micro=3, releaselevel='final', serial=0)

sys.api_version

此解释器的C API版本。

>>> import sys>>> sys.api_version1013

sys.stdin/sys.stdout/sys.stderr

标准输入、输出、错误。

>>> import sys
>>> sys.stdin
<_io.TextIOWrapper name=&#39;<stdin>&#39; mode=&#39;r&#39; encoding=&#39;utf-8&#39;>
>>> sys.stdout
<_io.TextIOWrapper name=&#39;<stdout>&#39; mode=&#39;w&#39; encoding=&#39;utf-8&#39;>
>>> sys.stderr
<_io.TextIOWrapper name=&#39;<stderr>&#39; mode=&#39;w&#39; encoding=&#39;utf-8&#39;>

常用方法

sys.exit()

退出程序，正常退出时exit(0)

import sysprint(sys.exit(0))print(sys.exit(1))

sys.modules

返回系统导入的模块字段，key是模块名，value是模块

>>> import sys
>>> sys.modules
{&#39;sys&#39;: <module &#39;sys&#39; (built-in)>, &#39;builtins&#39;: <module &#39;builtins&#39; (built-in)>, &#39;_frozen_importlib&#39;: <module &#39;importlib._bootstrap&#39; (frozen)>, &#39;_imp&#39;: <module &#39;_imp&#39; (built-in)>, &#39;_warnings&#39;: <module &#39;_warnings&#39; (built-in)>, &#39;_frozen_importlib_external&#39;: <module &#39;importlib._bootstrap_external&#39; (frozen)>, &#39;_io&#39;: <module &#39;io&#39; (built-in)>, &#39;marshal&#39;: <module &#39;marshal&#39; (built-in)>, &#39;nt&#39;: <module &#39;nt&#39; (built-in)>, &#39;_thread&#39;: <module &#39;_thread&#39; (built-in)>, &#39;_weakref&#39;: <module &#39;_weakref&#39; (built-in)>, &#39;winreg&#39;: <module &#39;winreg&#39; (built-in)>, &#39;time&#39;: <module &#39;time&#39; (built-in)>, &#39;zipimport&#39;: <module &#39;zipimport&#39; (frozen)>, &#39;_codecs&#39;: <module &#39;_codecs&#39; (built-in)>, &#39;codecs&#39;: <module &#39;codecs&#39; from &#39;D:\\Python3.8\\lib\\codecs.py&#39;>, &#39;encodings.aliases&#39;: <module &#39;encodings.aliases&#39; from &#39;D:\\Python3.8\\lib\\encodings\\aliases.py&#39;>, &#39;encodings&#39;: <module &#39;encodings&#39; from &#39;D:\\Python3.8\\lib\\encodings\\__init__.py&#39;>, &#39;encodings.utf_8&#39;: <module &#39;encodings.utf_8&#39; from &#39;D:\\Python3.8\\lib\\encodings\\utf_8.py&#39;>, &#39;_codecs_cn&#39;: <module &#39;_codecs_cn&#39; (built-in)>, &#39;_multibytecodec&#39;: <module &#39;_multibytecodec&#39; (built-in)>, &#39;encodings.gbk&#39;: <module &#39;encodings.gbk&#39; from &#39;D:\\Python3.8\\lib\\encodings\\gbk.py&#39;>, &#39;_signal&#39;: <module &#39;_signal&#39; (built-in)>, &#39;__main__&#39;: <module &#39;__main__&#39; (built-in)>, &#39;encodings.latin_1&#39;: <module &#39;encodings.latin_1&#39; from &#39;D:\\Python3.8\\lib\\encodings\\latin_1.py&#39;>, &#39;_abc&#39;: <module &#39;_abc&#39; (built-in)>, &#39;abc&#39;: <module &#39;abc&#39; from &#39;D:\\Python3.8\\lib\\abc.py&#39;>, &#39;io&#39;: <module &#39;io&#39; from &#39;D:\\Python3.8\\lib\\io.py&#39;>, &#39;_stat&#39;: <module &#39;_stat&#39; (built-in)>, &#39;stat&#39;: <module &#39;stat&#39; from &#39;D:\\Python3.8\\lib\\stat.py&#39;>, &#39;_collections_abc&#39;: <module &#39;_collections_abc&#39; from &#39;D:\\Python3.8\\lib\\_collections_abc.py&#39;>, &#39;genericpath&#39;: <module &#39;genericpath&#39; from &#39;D:\\Python3.8\\lib\\genericpath.py&#39;>, &#39;ntpath&#39;: <module &#39;ntpath&#39; from &#39;D:\\Python3.8\\lib\\ntpath.py&#39;>, &#39;os.path&#39;: <module &#39;ntpath&#39; from &#39;D:\\Python3.8\\lib\\ntpath.py&#39;>, &#39;os&#39;: <module &#39;os&#39; from &#39;D:\\Python3.8\\lib\\os.py&#39;>, &#39;_sitebuiltins&#39;: <module &#39;_sitebuiltins&#39; from &#39;D:\\Python3.8\\lib\\_sitebuiltins.py&#39;>, &#39;_locale&#39;: <module &#39;_locale&#39; (built-in)>, &#39;_bootlocale&#39;: <module &#39;_bootlocale&#39; from &#39;D:\\Python3.8\\lib\\_bootlocale.py&#39;>, &#39;types&#39;: <module &#39;types&#39; from &#39;D:\\Python3.8\\lib\\types.py&#39;>, &#39;importlib._bootstrap&#39;: <module &#39;importlib._bootstrap&#39; (frozen)>, &#39;importlib._bootstrap_external&#39;: <module &#39;importlib._bootstrap_external&#39; (frozen)>, &#39;warnings&#39;: <module &#39;warnings&#39; from &#39;D:\\Python3.8\\lib\\warnings.py&#39;>, &#39;importlib&#39;: <module &#39;importlib&#39; from &#39;D:\\Python3.8\\lib\\importlib\\__init__.py&#39;>, &#39;importlib.machinery&#39;: <module &#39;importlib.machinery&#39; from &#39;D:\\Python3.8\\lib\\importlib\\machinery.py&#39;>, &#39;importlib.abc&#39;: <module &#39;importlib.abc&#39; from &#39;D:\\Python3.8\\lib\\importlib\\abc.py&#39;>, &#39;_operator&#39;: <module &#39;_operator&#39; (built-in)>, &#39;operator&#39;: <module &#39;operator&#39; from &#39;D:\\Python3.8\\lib\\operator.py&#39;>, &#39;keyword&#39;: <module &#39;keyword&#39; from &#39;D:\\Python3.8\\lib\\keyword.py&#39;>, &#39;_heapq&#39;: <module &#39;_heapq&#39; (built-in)>, &#39;heapq&#39;: <module &#39;heapq&#39; from &#39;D:\\Python3.8\\lib\\heapq.py&#39;>, &#39;itertools&#39;: <module &#39;itertools&#39; (built-in)>, &#39;reprlib&#39;: <module &#39;reprlib&#39; from &#39;D:\\Python3.8\\lib\\reprlib.py&#39;>, &#39;_collections&#39;: <module &#39;_collections&#39; (built-in)>, &#39;collections&#39;: <module &#39;collections&#39; from &#39;D:\\Python3.8\\lib\\collections\\__init__.py&#39;>, &#39;_functools&#39;: <module &#39;_functools&#39; (built-in)>, &#39;functools&#39;: <module &#39;functools&#39; from &#39;D:\\Python3.8\\lib\\functools.py&#39;>, &#39;contextlib&#39;: <module &#39;contextlib&#39; from &#39;D:\\Python3.8\\lib\\contextlib.py&#39;>, &#39;importlib.util&#39;: <module &#39;importlib.util&#39; from &#39;D:\\Python3.8\\lib\\importlib\\util.py&#39;>, &#39;mpl_toolkits&#39;: <module &#39;mpl_toolkits&#39; (namespace)>, &#39;site&#39;: <module &#39;site&#39; from &#39;D:\\Python3.8\\lib\\site.py&#39;>, &#39;atexit&#39;: <module &#39;atexit&#39; (built-in)>}

sys.modules.keys()

返回所有已导入的模块名列表

>>> import sys
>>> sys.modules.keys()
dict_keys(['sys', 'builtins', '_frozen_importlib', '_imp', '_warnings', '_frozen_importlib_external', '_io', 'marshal', 'nt', '_thread', '_weakref', 'winreg', 'time', 'zipimport', '_codecs', 'codecs', 'encodings.aliases', 'encodings', 'encodings.utf_8', '_codecs_cn', '_multibytecodec', 'encodings.gbk', '_signal', '__main__', 'encodings.latin_1', '_abc', 'abc', 'io', '_stat', 'stat', '_collections_abc', 'genericpath', 'ntpath', 'os.path', 'os', '_sitebuiltins', '_locale', '_bootlocale', 'types', 'importlib._bootstrap', 'importlib._bootstrap_external', 'warnings', 'importlib', 'importlib.machinery', 'importlib.abc', '_operator', 'operator', 'keyword', '_heapq', 'heapq', 'itertools', 'reprlib', '_collections', 'collections', '_functools', 'functools', 'contextlib', 'importlib.util', 'mpl_toolkits', 'site', 'atexit'])

sys.getdefaultencoding()

返回Unicode实现使用的当前默认字符串编码的名称。

>>> import sys
>>> sys.getdefaultencoding()'utf-8'

sys.getfilesystemencoding()

返回用于在Unicode文件名和字节文件名之间进行转换的编码名称

>>> import sys
>>> sys.getfilesystemencoding()utf-8

sys.getrecursionlimit()

返回最大递归次数

>>> import sys
>>> sys.getrecursionlimit()  
# 查看当前解释器的最大递归深度1000

sys.setrecursionlimit(num)

设置最大递归次数

>>> import sys
>>> sys.setrecursionlimit(1100)  
# 将解释器的最大递归深度设置为1100
>>> sys.getrecursionlimit()  
# 再次查看当前解释器的最大递归深度1100

sys.getsizeof()

获取对象占用的内存大小（用字节表示）

>>> import sys
>>> for obj in [int(), float(), list(), tuple(), set(), dict(), object]:...     print(str(obj.__class__).ljust(20), sys.getsizeof(obj))...<class &#39;int&#39;>        24<class &#39;float&#39;>      24<class &#39;list&#39;>       56<class &#39;tuple&#39;>      40<class &#39;set&#39;>        216<class &#39;dict&#39;>       232<class &#39;type&#39;>       416

sys.getrefcount(obj)

返回obj的引用计数。返回的计数通常比预期的高一个，因为它包含（临时）引用作为参数。

>>> import sys
>>> a = [1,2,3]
>>> b = a
>>> c = b
>>> sys.getrefcount(a)4

sys.exc_info()

获取当前正在处理的异常类，exc_type、exc_value、exc_traceback当前处理的异常详细信息

>>> import sys
>>> sys.exc_info()(None, None, None)

sys.getwindowsversion()

获取Windows的版本，Windows系统中有效

>>> import sys
>>> sys.getwindowsversion()sys.getwindowsversion(major=10, minor=0, build=19041, platform=2, service_pack='')

sys.stdin.readline()

从标准输入读一行，会读取末尾的换行符

sys.stdout.write()

向标准输出写入内容

>>> import sys
>>> sys.stdout.write("hello world")hello world11

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