python-core-file-management

Öffnen, lesen, schreiben §

with open(filename, "r+") as file:
	if "search pattern" in file.read():
		return file
 
with open(filename, "a") as file:
	file.write("Append this.")
 
with open(filename, "w") as file:
	file.writelines("This is written to the file.")

Access Modes

• Read Only (r)
• Read and Write (r+) → Raises I/O error if the file does not exist.
• Write Only (w)
• Write and Read (w+) → For an existing file, data is truncated and over-written.
• Append Only (a)
• Append and Read (a+)

---

• + means that the file is created if it doesn’t exist when used for writing and appending.

Working with pathlib §

import Path from pathlib
 
# Two parent directories up from this one
two_dirs_up = Path(__file__).resolve().parent.parent
 
path = Path.home() / "folder" 
# This actually results in "$HOME/folder". I mean... wha-?

Working with os §

import os
 
os.path.join(path, name)
 
os.listdir(path) # Top level dir
os.walk(path) # Dir and all subdirs
 
os.path.isfile(file)
os.path.isdir(directory)

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Tips and tricks

is_markdown = filename.endswith(".md")

Ressourcen

• Python: Open a file, search then append, if not exist - Stack Overflow
• if statement - Why does python use ‘else’ after for and while loops? - Stack Overflow
• Python: Open a file, search then append, if not exist - Stack Overflow
• How to replace all instances of a string in text file with Python 3? - Stack Overflow