Entity tag (Etag) sums

This very simple and naïve program computes entity tag (Etag) checksums, à la those reported by various AWS components.

See also https://nonempty.org/software/etagsum.

About

This software is in no way affiliated with AWS.

The code is licensed under the GNU General Public License, verson 3.0.

Installing

For now, etagsum is just a single executable Python script bin/etagsum, and can be installed any way you like. All Python 3 versions should be supported.

Running

Invocations are similar to those of sha256sum and friends from GNU Coreutils, but one needs to explicitly specify the chunk size. This is done with the --size switch. In

etagsum --size 8M a b --size 16M c

the files a and b are checksummed with a chunk size of 8 MB, and c with a size of 16 MB. AWS tools tend to pick 8 or 16 MB as defaults.

More options can be seen by running etagsum --help.