What are the commonly used methods in python os library?

Commonly used functions and methods

In Python, the os library provides a large number of operating system-related functions and methods.

The following are some commonly used functions and methods and their detailed introduction, cases and complete comments:

getcwd() function:

Get the current working directory.

import os
# 获取当前工作目录
current_dir = os.getcwd()
print(current_dir)

In the above code, we use the getcwd() function to get the current working directory and assign it to the variable current_dir. This function returns a string representing the path to the current working directory.

listdir() function:

List all files and subdirectories in the specified directory

import os
# 列出当前工作目录下的所有文件和子目录
files = os.listdir('.')
for file in files:
    print(file)

In the above code, we use listdir()The function lists all files and subdirectories in the current working directory and assigns them to the variable files. We then used for to loop through all the files and subdirectories and print out their names.

• mkdir()Method: Create a new directory.

import os
# 在当前工作目录下创建一个名为'new_dir'的新目录
new_dir_path = os.path.join(os.getcwd(), 'new_dir')
os.mkdir(new_dir_path)

In the above code, we use the mkdir() method to create a new directory named 'new_dir' in the current working directory. Note that if the directory already exists, an exception will be thrown.

• rmdir()Method: Delete the specified directory.

import os
# 删除指定目录
dir_path = os.path.join(os.getcwd(), 'new_dir')
os.rmdir(dir_path)

In the above code, we use the rmdir() method to delete the previously created 'new_dir' directory. It should be noted that when performing file or directory operations, you should always consider how to handle exceptions and pay attention to checking permissions to ensure the legality of the operation.

• rename()Method: Rename the file or move the file to a new location.

import os
# 将文件从当前工作目录下移动到新目录中并重命名
file_path = os.path.join(os.getcwd(), 'example.txt')
new_file_path = os.path.join(os.getcwd(), 'new_dir', 'new_example.txt')
os.rename(file_path, new_file_path)

In the above code, we use the rename() method to move the previously created 'example.txt' file to the new directory 'new_dir', and rename it to 'new_example.txt'. If the target file already exists, it will be overwritten.

• remove()Method: Delete the specified file.

import os
# 删除指定文件
file_path = os.path.join(os.getcwd(), 'new_dir', 'new_example.txt')
os.remove(file_path)

In the above code, we use the remove() method to delete the 'new_example.txt' file just created.

path.exists() function:

• Check whether the specified path exists.

import os
# 检查文件是否存在
file_path = os.path.join(os.getcwd(), 'example.txt')
if os.path.exists(file_path):
    print('文件存在')
else:
    print('文件不存在')

In the above code, we checked whether the 'example.txt' file exists using the exists() function. If the file exists, print 'File exists', otherwise print 'File does not exist'.

path.isdir() function:

Check whether the specified path is a directory.

import os
# 判断指定路径是否为目录
dir_path = os.path.join(os.getcwd(), 'new_dir')
if os.path.isdir(dir_path):
    print('是一个目录')
else:
    print('不是一个目录')

In the above code, we use the isdir() function to determine whether the 'new_dir' path is a directory. If so, print out 'is a directory', otherwise print out 'is not a directory'.

path.isfile() function:

• Check whether the specified path is a file.

import os
# 判断指定路径是否为文件
file_path = os.path.join(os.getcwd(), 'example.txt')
if os.path.isfile(file_path):
    print('是一个文件')
else:
    print('不是一个文件')

In the above code, we use the isfile() function to determine whether the 'example.txt' path is a file. If so, print 'is a file', otherwise print 'is not a file'.

path.join() function:

• Join paths.

import os
# 将多个部分拼接成一个路径
path = os.path.join(os.getcwd(), 'new_dir', 'new_example.txt')
print(path)

In the above code, we use the join() function to concatenate the current working directory, new directory name and new file name into a complete path, and print it out.

path.basename() function:

• Get the file name or last-level directory name in the path.

import os
# 获取路径中的文件名或最后一级目录名
file_path = os.path.join(os.getcwd(), 'new_dir', 'new_example.txt')
dir_name = os.path.basename(os.path.dirname(file_path))
file_name = os.path.basename(file_path)
print(dir_name)
print(file_name)

In the above code, we use the dirname() function to get the directory name where the 'new_example.txt' file is located, and then use basename( )The function gets the last-level directory name of the directory name (i.e. 'new_dir') and assigns it to the variable dir_name. Next, we use the basename() function to get the 'new_example.txt' file name and assign it to the variable file_name. Finally, we print out the values ​​of these two variables.

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