Popular File related problems and solutions using Python

We share clean solutions for some of the most popular questions you may encounter when you process files or directories using Python. 

1. How to check whether a file exists using Python?

   import os.path os.path.exists(file_path)

   1 2	import os.path os.path.exists(file_path)

2. How to check whether a path is a file?

   You can use the os.path.isfile function:
   It returns True if path is an existing regular file. This follows symbolic links, so both islink() andisfile() can be true for the same path.

   import os.path os.path.isfile(fname)

   1 2	import os.path os.path.isfile(fname)

3. How to make sure an directory exist?

   import os import errno def ensure_dir_exist(path): try: if not os.path.exists(path): os.makedirs(path) except OSError as exception: if exception.errno != errno.EEXIST: raise

   1 2 3 4 5 6 7 8 9 10

   import os import errno   def ensure_dir_exist(path):     try:         if not os.path.exists(path):             os.makedirs(path)     except OSError as exception:         if exception.errno != errno.EEXIST:             raise

4. How to list all files of a directory in Python

   from os import listdir from os.path import isfile, join path ="/" onlyfiles = [f for f in listdir(path) if isfile(join(path, f))]

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   from os import listdir from os.path import isfile, join path ="/" onlyfiles = [f for f in listdir(path) if isfile(join(path, f))]

   or

   from os import walk f = [] for (dir_path, dir_names, file_names) in walk(path): f.extend(file_names) break

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   from os import walk f = [] for (dir_path, dir_names, file_names) in walk(path):     f.extend(file_names)     break

    

5. How to read a file line by line into a list with Python

   lines = [] with open("file.txt", "r") as f: for line in f: line = line.strip() # process your line here lines.append(line)

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   lines = [] with open("file.txt", "r") as f:   for line in f:     line = line.strip() # process your line here     lines.append(line)

    

6. How to append a line to file in Python?

   with open("test.txt", "a") as f: f.write("new line")

   1 2	with open("test.txt", "a") as f:     f.write("new line")

7.  How to remove a file in Python?

   os.remove() will remove a file.

   os.rmdir() will remove an empty directory.

   shutil.rmtree() will delete a directory and all its contents.

   os.remove('test.txt') will remove file test.txt  from the current working directory. os.remove('/home/user/test.txt') will remove /home/user/test.txt 

Please leave a comment if you want to add more problems and solutions.