Pathlib

Python · Reference cheat sheet

📋 Overview

pathlib.Path is the modern object-oriented path API. Prefer it over os.path string munging. Paths use / operator, work cross-platform, and integrate with open/read/write helpers.

🔧 Core concepts

Use PurePath when you only need parsing without touching the filesystem.

💡 Examples

Build and inspect:

from pathlib import Path

base = Path(__file__).resolve().parent
data = base / "data" / "input.csv"
print(data.name, data.suffix, data.parent)
print(data.with_suffix(".json"))

Read / write:

from pathlib import Path

p = Path("notes.txt")
p.write_text("hello\n", encoding="utf-8")
text = p.read_text(encoding="utf-8")
p.write_bytes(b"\x00\x01")

Walk and filter:

root = Path("src")
for py in sorted(root.rglob("*.py")):
    if py.is_file() and "test" not in py.parts:
        print(py.relative_to(root))

mkdir / safe delete:

out = Path("build/out")
out.mkdir(parents=True, exist_ok=True)
tmp = out / "tmp.txt"
tmp.write_text("x", encoding="utf-8")
tmp.unlink(missing_ok=True)

⚠️ Pitfalls

• Relative paths depend on process cwd — anchor with Path(__file__).parent.
• Always pass encoding for text helpers.
• Path.glob("**/*") can be huge; narrow patterns.
• Mixing str paths and Path works often, but keep one style in APIs.
• resolve(strict=True) raises if the path does not exist.

🔗 Related

• Files I/O
• Examples: manage files
• Context managers
• Strings
• JSON
• Import / export