rename-after-writing 0.0.12

Safe copy, move, and write on remote drives

A python-library to help with the completeness of files when moving, copying and writing. Writing a file is not atomic. In the worst case the process writing the file dies while the file is not yet complete. Also in some network-file-systems, the destination of a move or copy might show up before it is complete. Incomplete files are a potential risk for the integrity of your data. In the best case your reading process crashes, but in the worst case the incompleteness goes unnoticed. This package reduces the risk of having incomplete files by making all writing operations write to a temporary file in the destination’s directory first before renaming it to its final destination. On most file-systems this final renamig is atomic.

Install

pip install rename_after_writing

Functions

Path

Writes to a temporary path and move it to your desired path on exit.

import rename_after_writing as rnw

with rnw.Path(path="my_file.txt") as tmp_path:
    with open(tmp_path, "wt") as f:
        for i in range(10):
            f.write(input())

Note, that while you write to the file (while you provide input()) the file is written into a temporary file named path + . + uuid(). After writing, on exit of the contextmanager, the temporary file is moved to path.

open

Just like python’s built in open() but when writing (mode=w) everything is writen to a temporary file in the destination’s directory before the temporary file is renamed to the final destination.

import rename_after_writing as rnw

with rnw.open("my_file.txt", "wt") as f:
    for i in range(10):
        f.write(input())

copy

Copies the file first to a temporary file in the destinations directory before moving it to its final path.

import rename_after_writing as rnw

rnw.copy(src="machine/with/src", dst="other/machine/in/network/dst")

move

Some implementations of network-file-systems might raise an OSError with errno.EXDEV when an os.rename() is going across the boundary of a physical drive. In this case, this package’s copy is used to copy the file beore unlinking the source-file.

import rename_after_writing as rnw

rnw.move(src="machine/with/src", dst="other/machine/in/network/dst")