Python os.confstr()

Python os.confstr() 方法用于获取字符串值的系统配置值。它通常接受一个字符串参数 name 它指定要检索的配置值。

的所有可能值 name 的键给出 confstr_names 字典。我们也可以传递一个整数值 name 参数用于字典中不包含的配置变量。

方法指定的配置变量 name 参数不是由系统定义的 os.confstr() 方法将返回 None 如果名称没有指定任何现有的配置变量，那么 ValueError 例外。此外，如果主机操作系统不支持该配置值， OSError 例外。

Note: os.confstr() 方法仅在UNIX平台上可用。

语法: os.confstr(name)

参数:

name:表示系统配置变量的字符串或整数值。

返回类型: 此方法返回一个字符串值，该值表示与指定配置变量对应的配置值。

示例1

使用os.confstr()方法

# Python program to explain os.confstr() method
    
# importing os module 
import os
  
# System Configuration variable
name = "CS_GNU_LIBC_VERSION"
  
  
# Get the configuration value
# corresponding to the
# specified configuration 
# variable using os.confstr() method
value = os.confstr(name)
  
# Print the configuration value
print("% s :" % name, value) 
  
  
# System Configuration variable
name = "CS_PATH"
  
# Get the configuration value
# corresponding to the 
# specified configuration 
# variable using os.confstr() method
value = os.confstr(name)
  
  
# Print the configuration value
print("% s :" % name, value)
  
# We can also pass an integer 
# value for name parameter.
# for example
conf_var = "CS_GNU_LIBC_VERSION"
name = os.confstr_names[conf_var]
print("\nInteger value corresponding to % s:" % conf_var, name)
  
# Get the configuration value
# corresponding to the 
# specified integer value 
# using os.confstr() method
value = os.confstr(name)
  
# Print the configuration value
print("Configuration value corresponding to % s :" % name, value)
  
# Note: -1 is returned if the
# configuration variable is not defined
# by the system 

输出:

CS_GNU_LIBC_VERSION : glibc 2.26
CS_PATH : /bin:/usr/bin

Integer value corresponding to CS_GNU_LIBC_VERSION: 2
Configuration value corresponding to 2 : glibc 2.26

示例2

使用os.confstr()方法时可能出现的错误

# Python program to explain os.confstr() method
    
# importing os module 
import os
  
# System Configuration variable
name = "cs_PATH"
  
  
# If the specified name 
# is not a configuration variable
# then ValueError Exception 
# is raised
  
value = os.confstr(name)
print("% s:" % name, value)
  
  
# Similarly, if the a specific
# value for name parameter is
# not supported by host operating system
# then OSError exception
# is raised.

输出:

Traceback (most recent call last):
  File "confstr.py", line 15, in 
    value = os.confstr(name)
ValueError: unrecognized configuration name

示例3

使用os.confstr()方法时处理可能的错误

# Python program to explain os.confstr() method
    
# importing os module 
import os
  
# System Configuration variable
name = "cs_PATH"
  
# we can handle exception
# using try and except block
  
# Try getting the system 
# configuration value corresponding 
# to specified configuration variable
try :
    value = os.confstr(name)
    print("% s:" % name, value)
  
# If the specified name is
# not a configuration variable
except ValueError :
    print("'% s' is not a configuration variable" % name)
  
# If the specified name is
# not supported by the 
# operating system 
except OSError :
    print("'% s' is not supported by Operating system" % name) 

输出:

'cs_PATH' is not a configuration variable