Python os.chdir() 方法

2024 年 8 月 29 日 | 阅读 11 分钟

Python 的 os 模块包含 chdir() 函数。当前工作目录用于利用默认路径来执行命令、创建目录和创建文件。当前工作目录经常用于 bash、MS-DOS 和 PowerShell 等命令行界面中的命令和函数。要更改当前工作目录，请使用 chdir() 方法。

关于 os 模块

在处理 Python 时，有很多时候我们希望利用底层操作系统的特性。这可以通过 Python 的 os 模块来实现，该模块允许我们以多种方式与底层操作系统进行通信，并提供了一种可移植的机制来运用操作系统依赖的功能。Python 内置的操作系统依赖模块设计得当，只要相同的功能可用，它们都会使用相同的接口。

os 模块还提供了特定于给定操作系统的扩展，尽管使用它们最终会影响可移植性。所有接受路径或文件名的函数都接受字节和字符串对象作为输入，如果返回路径或文件名，输出也是相同类型的对象。当文件名称和路径不正确或不可用，或者其他类型正确但未被操作系统识别的参数出现时，Python os 模块中的所有方法都会引发 OSError（或其子类）。

os 模块允许您在移动中（on the go）使用操作系统依赖的功能。如果您只想读取或写入文件，请使用 open()；如果您想更改路径，请使用 os.path 模块；如果您想读取命令行中所有文件的所有行，请使用文件输入模块。tempfile 模块可用于创建临时文件和目录，而 shutil 模块可以处理高级文件和目录操作。

关于这些功能可用性的注意事项

Python 的所有内置操作系统依赖模块的设计都是这样，只要相同的功能可用，它们都使用相同的接口；例如，函数 os.stat(path) 以相同的方式提供关于路径的 stat 信息（这恰好源于 POSIX 接口）。
os 模块还提供了特定于给定操作系统的扩展；但是，使用它们会影响可移植性。
如果提供了路径或文件名，所有处理路径或文件名的函数都接受字节和字符串对象，并返回相同类型的对象。
popen、os.fork、os.execv 和 os.spawn*p* 在 VxWorks 上不受支持。

代码

# a sample python code to show the usage of chdir() method provided by the OS library of the python 

# importing the required libraries 
import os
import sys

#  a class is written that will have its member functions which will perform various operations like Changing of the current directory to another directory which will be specified as a parameter to that function and listing the content of a particular directory
class NirnayOSClass:

    def __init__(self):
        pass
    # this function is used to to print the  the current working directory of the program execution there is no parameter to this function and it also doesn't return any value it will just print the current working directory
    def print_current_working_directory(self):
        cwd = os.getcwd()
        print("The present working directory is {}".format(cwd))

    #  this function is used to change the current working directory to the new directory which is specified as a parameter to this function this function performs the the operation of changing the present working directory there is one parameter to this function that holds the path to the new current working directory to which we want to change the return type of this function is Boolean that means it returns true on the successful change of directory to the new current working directory and on the other hand if the specified path to which we want to change is invalid or there is some issue while changing the current working directory the return type of this function will be changed to false
    def changed_current_working_directory(self,path_to_new_dir):
        cwd = os.getcwd()
        return_code = os.chdir(path_to_new_dir)

        print("Directory changed from {} to {}.".format(cwd,path_to_new_dir))
    
    #  this function is used to list the contents of a particular directory this function performs a similar task as of LS command in Linux there is one parameter to this function which is the part of the directory whose content we want to list  the directory which is passed as a parameter to this function will be considered as the current working directory of the program executions and all the files and directories inside that particular directory are listed.
    def list_files_in_the_directory(self,dir_path_to_list):
        dir_path_to_list = os.getcwd()
        list_of_contents = os.listdir(dir_path_to_list)
        print("The contents in the current directory are::")

        for file_or_folder_name in list_of_contents:
            print(file_or_folder_name,end="\t")
        print()

# the main function is used to create the object of the above-written class and call various functions that will perform different operations like printing the current working directory changing the current working directory to a new directory which is specified as a parameter to that function and in the last listing all the contents of a particular directory 
def main():

    while(True):
        print("Please choose one of the appropriate options::")
        print("1. To check the current directory of the code execution. (using the getcwd() function)")
        print("2. To change the current directory of the    code execution. (using the chdir() function)")
        print("3. To list the contents of the directory of the code execution. (using the listdir() function)")
        print("4. To exit from the code execution.")
        menu_choice = input()
        menu_choice = int(menu_choice)

        dir_entity = NirnayOSClass()

        # If the user chooses the first option which is printing the current working directory so once the user chooses the first option the user is displayed with the complete absolute path of the current working directory in which the code is getting executed right now
        if menu_choice == 1:
            dir_entity.print_current_working_directory()

        #  on the selection of the second choice which is changing of the current working directory of the code execution first of all the user is asked for the complete absolute path of the new directory to which we want to change the current working directory so once the user provides the new   absolute path the user is prompted with the message saying that it the current working directory of the code execution has been changed successfully on the successful change of director
        elif menu_choice == 2:
            print(">Enter the absolute path to the new directory to which we want to change::")
            input_str = input()
            dir_entity.changed_current_working_directory(input_str)
            

        #  if the user Third option which is listing the contents of the current working directory all the contents of the current working directory in which the code is getting executed are listed incase if the user has changed the current working directory the content of the latest directory to which the user has moved are displayed 
        elif menu_choice == 3:
            input_str = ""
            dir_entity.list_files_in_the_directory(input_str)
        
        print("Do you want to continue or exit the code execution?[y/n]")
        continue_or_exit = input()

        #After the completion of one round a question is prompted to the user asking whether you want to continue the code execution or you want to exit the code depending upon the input provided by the user further actions are taken if the user wants to continue the code execution and perform further operations related to dir and listing of the dir, the code is continued whereas on the other hand if the user wants to exit the code execution the exit function is called and the program is ended
        if continue_or_exit == 'y' or continue_or_exit == 'Y':
            pass
        elif continue_or_exit == 'n' or continue_or_exit == 'N':
            sys.exit()

if __name__ == '__main__':
    main()

输出

Please choose one of the appropriate options::
1. To check the current directory of the code execution. (using the getcwd() function)
2. To change the current directory of the code execution. (using the chdir() function)
3. To list the contents of the directory of the code execution. (using the listdir() function)
4. To exit from the code execution.
1
The present working directory is /
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To check the current directory of the code execution. (using the getcwd() function)
2. To change the current directory of the code execution. (using the chdir() function)
3. To list the contents of the directory of the code execution. (using the listdir() function)
4. To exit from the code execution.
2
>Enter the absolute path to the new directory to which we want to change::
level_1_dir
Directory changed from / to level_1_dir.
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To check the current directory of the code execution. (using the getcwd() function)
2. To change the current directory of the code execution. (using the chdir() function)
3. To list the contents of the directory of the code execution. (using the listdir() function)
4. To exit from the code execution.
1
The present working directory is /level_1_dir
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To check the current directory of the code execution. (using the getcwd() function)
2. To change the current directory of the code execution. (using the chdir() function)
3. To list the contents of the directory of the code execution. (using the listdir() function)
4. To exit from the code execution.
3
The contents in the current directory are::
level_2_dir_1	level_2_dir_2	level_2_dir_3	
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To check the current directory of the code execution. (using the getcwd() function)
2. To change the current directory of the code execution. (using the chdir() function)
3. To list the contents of the directory of the code execution. (using the listdir() function)
4. To exit from the code execution.
2
>Enter the absolute path to the new directory to which we want to change::
level_2_dir_1
Directory changed from /level_1_dir to level_2_dir_1.
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To check the current directory of the code execution. (using the getcwd() function)
2. To change the current directory of the code execution. (using the chdir() function)
3. To list the contents of the directory of the code execution. (using the listdir() function)
4. To exit from the code execution.
1
The present working directory is /level_1_dir/level_2_dir_1
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To check the current directory of the code execution. (using the getcwd() function)
2. To change the current directory of the code execution. (using the chdir() function)
3. To list the contents of the directory of the code execution. (using the listdir() function)
4. To exit from the code execution.
3
The contents in the current directory are::
test_files_1_2_1_no4	test_files_1_2_1_no9	test_files_1_2_1_no8	test_files_1_2_1_no1	test_files_1_2_1_no7	test_files_1_2_1_no6	test_files_1_2_1_no10	test_files_1_2_1_no2	test_files_1_2_1_no3	test_files_1_2_1_no5	
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To check the current directory of the code execution. (using the getcwd() function)
2. To change the current directory of the code execution. (using the chdir() function)
3. To list the contents of the directory of the code execution. (using the listdir() function)
4. To exit from the code execution.
2
>Enter the absolute path to the new directory to which we want to change::
/level_1_dir/level_2_dir_3
Directory changed from /level_1_dir/level_2_dir_1 to /level_1_dir/level_2_dir_3.
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To check the current directory of the code execution. (using the getcwd() function)
2. To change the current directory of the code execution. (using the chdir() function)
3. To list the contents of the directory of the code execution. (using the listdir() function)
4. To exit from the code execution.
1
The present working directory is /level_1_dir/level_2_dir_3
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To check the current directory of the code execution. (using the getcwd() function)
2. To change the current directory of the code execution. (using the chdir() function)
3. To list the contents of the directory of the code execution. (using the listdir() function)
4. To exit from the code execution.
3
The contents in the current directory are::
test_files_1_2_3_no7	test_files_1_2_3_no8	test_files_1_2_3_no3	test_files_1_2_3_no5	test_files_1_2_3_no10	level_3_dir	test_files_1_2_3_no9	test_files_1_2_3_no6	test_files_1_2_3_no2	test_files_1_2_3_no4	test_files_1_2_3_no1	
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To check the current directory of the code execution. (using the getcwd() function)
2. To change the current directory of the code execution. (using the chdir() function)
3. To list the contents of the directory of the code execution. (using the listdir() function)
4. To exit from the code execution.
2
>Enter the absolute path to the new directory to which we want to change::
level_3_dir
Directory changed from /level_1_dir/level_2_dir_3 to level_3_dir.
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To check the current directory of the code execution. (using the getcwd() function)
2. To change the current directory of the code execution. (using the chdir() function)
3. To list the contents of the directory of the code execution. (using the listdir() function)
4. To exit from the code execution.
1
The present working directory is /level_1_dir/level_2_dir_3/level_3_dir
Do you want to continue or exit the code execution?[y/n]
y
Please choose one of the appropriate options::
1. To check the current directory of the code execution. (using the getcwd() function)
2. To change the current directory of the code execution. (using the chdir() function)
3. To list the contents of the directory of the code execution. (using the listdir() function)
4. To exit from the code execution.
3
The contents in the current directory are::
test_file1	test_file8	test_file2	test_file4	test_file3	test_file5	test_file7	test_file6	test_file9	test_file10	
Do you want to continue or exit the code execution?[y/n]
n

说明

现在我们来看上面代码的输出。在上面编写的代码中，我们为与目录相关的不同功能创建了不同的函数。这些功能包括打印代码执行的当前工作目录，以及将代码执行的当前工作目录更改为新的工作目录。最后，另一项功能是列出当前工作目录中的所有内容。最后，编写了一个菜单驱动的代码，用于向用户提供所有这三个功能作为选项。

在执行中，我们在根目录下执行了代码。之后，我们需要将代码执行的当前工作目录更改为一级目录，其中包含三个子目录，我们通过选择打印一级目录所有内容的第三个选项来确认这一点。现在代码执行的当前工作目录是一级目录，现在我们选择了选项二，将代码执行的当前工作目录更改为二级目录 1。然后，我们通过选择列出当前工作目录中所有内容的选项来列出该目录的内容。我们执行这些步骤几次，并通过选择代码询问是否要继续执行代码或暂停执行代码的选项来结束代码执行。

所以在这篇文章中，我们已经看到了如何使用 Python 的 OS 模块提供的 chdir() 方法。我们还通过示例代码理解了此函数的各种用例场景和实际实现。

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