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File existence checking with os.path

In Python, attempting to open a file that does not exist using the default open() function will result in a FileNotFoundError^[400-devops-09-scripting-language-python-introduction-part-2files-readme.md:77-80]. To prevent this runtime error, it is best practice to check for a file's existence before attempting to read from it^[400-devops-09-scripting-language-python-introduction-part-2files-readme.md:81-84].

Using os.path.isfile

To check if a file exists, the os.path built-in module is required^[400-devops-09-scripting-language-python-introduction-part-2files-readme.md:81-84]. The module provides the os.path.isfile() function, which accepts a file path as an argument and returns a boolean result^[400-devops-09-scripting-language-python-introduction-part-2files-readme.md:85-88].

Implementation Example

Typically, os.path.isfile() is combined with conditional logic to handle the file operation safely^[400-devops-09-scripting-language-python-introduction-part-2files-readme.md:89-95].

import os.path

if os.path.isfile("customers.log"):
  print("file exists")
else:
  print("file does not exists")

Practical Application

Checking file existence allows a program to dynamically handle missing data sources.^[400-devops-09-scripting-language-python-introduction-part-2files-readme.md:81-84] For example, an application can verify if a data file is present and either proceed to read the data or return an empty dictionary if the file is not found^[400-devops-09-scripting-language-python-introduction-part-2files-readme.md:241-250].

  • File I/O
  • [[CSV module]]
  • [[Python exception handling]]
  • [[Docker for Python development]]

Sources

  • 400-devops-09-scripting-language-python-introduction-part-2files-readme.md