mirror of
https://github.com/kevinveenbirkenbach/create-linux-swapfile.git
synced 2025-10-09 17:08:08 +02:00
Kevin Veen-Birkenbach
8a41ce8e25
- Added btrfs-safe handling (/var/swap/swapfile) - Automatically recreates swapfile if size differs - Removed legacy main.sh Conversation: https://chatgpt.com/share/68d2c38b-84dc-800f-9ca4-dffa158c8e80
114 lines
3.4 KiB
Python
114 lines
3.4 KiB
Python
#!/usr/bin/env python3
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import argparse
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import os
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import re
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import shutil
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import subprocess
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from pathlib import Path
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FSTAB_FILE = Path("/etc/fstab")
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BTRFS_SWAP_DIR = Path("/var/swap")
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BTRFS_SWAP_PATH = BTRFS_SWAP_DIR / "swapfile"
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DEFAULT_SWAP_PATH = Path("/swapfile")
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def run(cmd, check=True, capture=False):
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"""Helper to run shell commands."""
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kwargs = {"check": check}
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if capture:
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kwargs["stdout"] = subprocess.PIPE
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kwargs["stderr"] = subprocess.PIPE
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kwargs["text"] = True
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return subprocess.run(cmd, **kwargs)
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def detect_root_fs() -> str:
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result = run(["findmnt", "-no", "FSTYPE", "/"], capture=True)
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return result.stdout.strip()
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def parse_size_to_mib(size: str) -> int:
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"""Convert '64G' or '2048M' into MiB integer."""
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match = re.match(r"^(\d+)([gGmM]?[bB]?)?$", size.strip())
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if not match:
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raise ValueError(f"Invalid size format: {size}")
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num, unit = match.groups()
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num = int(num)
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unit = (unit or "M").lower()
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if unit in ("g", "gb"):
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return num * 1024
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elif unit in ("m", "mb"):
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return num
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else:
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raise ValueError(f"Unsupported unit: {unit}")
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def get_swap_size(path: Path) -> int:
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"""Return swapfile size in MiB if it exists, else 0."""
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if not path.exists():
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return 0
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return path.stat().st_size // (1024 * 1024)
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def remove_swap(path: Path):
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"""Disable and remove swapfile and its fstab entry."""
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run(["swapoff", str(path)], check=False)
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if path.exists():
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path.unlink()
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# remove old fstab line
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if FSTAB_FILE.exists():
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text = FSTAB_FILE.read_text().splitlines()
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new_lines = [
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line for line in text
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if not re.search(rf"^{re.escape(str(path))}\s+none\s+swap", line)
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]
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FSTAB_FILE.write_text("\n".join(new_lines) + "\n")
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def create_swap(path: Path, size_mib: int, fs: str):
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if fs == "btrfs":
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print(f"Creating {size_mib} MiB swapfile on btrfs at {path}")
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path.parent.mkdir(parents=True, exist_ok=True)
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run(["chattr", "+C", str(path.parent)], check=False)
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run(["btrfs", "property", "set", "-ts", str(path.parent), "compression", "none"], check=False)
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run([
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"dd", "if=/dev/zero", f"of={path}", "bs=1M",
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f"count={size_mib}", "status=progress"
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])
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else:
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print(f"Creating {size_mib} MiB swapfile on {fs} at {path}")
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run(["fallocate", "-l", f"{size_mib}M", str(path)])
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run(["chmod", "600", str(path)])
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run(["mkswap", str(path)])
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run(["swapon", str(path)])
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with FSTAB_FILE.open("a") as f:
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f.write(f"{path} none swap sw 0 0\n")
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def main():
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parser = argparse.ArgumentParser(description="SwapForge Python edition")
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parser.add_argument("size", help="Swapfile size (e.g. 2048M or 64G)")
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args = parser.parse_args()
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fs = detect_root_fs()
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path = BTRFS_SWAP_PATH if fs == "btrfs" else DEFAULT_SWAP_PATH
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new_size = parse_size_to_mib(args.size)
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old_size = get_swap_size(path)
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if old_size == new_size and old_size > 0:
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print(f"Swapfile {path} already exists with correct size ({old_size} MiB). Skipping.")
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return
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if old_size > 0 and old_size != new_size:
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print(f"Existing swapfile {path} has size {old_size} MiB, expected {new_size} MiB. Recreating...")
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remove_swap(path)
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create_swap(path, new_size, fs)
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print("Done.")
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if __name__ == "__main__":
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main()
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