| Description: | Atomically write to a file on POSIX-compliant systems while preserving
permissions.
On most Unix systems, `mv` is an atomic operation. This makes it simple to
write to a file atomically just by using the mv operation. However, this will
destroy the permissions on the original file. This library does the following
to preserve permissions while atomically writing to a file:
* If an original file exists, take those permissions and apply them to the temp
file before `mv`ing the file into place.
* If the original file does not exist, create a following with default
permissions (based on the currently-active umask).
This way, when the file is `mv`'ed into place, the permissions will be the ones
held by the original file.
This library is based on similar implementations found in common libraries in
Ruby and Python:
* <http://apidock.com/rails/File/atomic_write/class Ruby on Rails includes a
similar method called atomic_write>
*
<https://github.com/chef/chef/blob/c4631816132fcfefaba3d123a1d0dfe8bc2866bb/lib/chef/file_content_management/deploy/mv_unix.rb#L23:L71
Chef includes atomic update functionality>
* <https://github.com/sashka/atomicfile There is a python library for
atomically updating a file>
To use `atomic-write`, import the module corresponding to the type you wish to
write atomically, e.g., to write a (strict) ByteString atomically:
> import System.AtomicWrite.Writer.ByteString
Then you can use the atomicWriteFile function that accepts a `FilePath` and a
`ByteString`, e.g.:
> atomicWriteFile myFilePath myByteString. |
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