recursum

Rust script to hash many files, quickly.

There are 3 modes of operation.

1. The original, and the root of the crate's name, is recursively checking every (non-symlink) file in a given directory tree.
2. Hash a single given file.
3. Take a list of files from stdin and hash each of them.

Parallelises file discovery (in usage #1) and hashing (#1 and #3). Default hasher is not cryptographically secure.

"{path}"\t{hex_digest} printed to stdout; progress information on stderr.

Contributions welcome.

Usage

``` recursum Hash lots of files fast, in parallel.

USAGE: recursum [OPTIONS]

FLAGS: -h, --help Prints help information -V, --version Prints version information

OPTIONS: -d, --digest Maximum length of output hash digests -t, --threads Hashing threads -w, --walkers Directory-walking threads, if input is a directory

ARGS: File name, directory name (every file recursively will be hashed, in depth first order), or '-' for getting list of files from stdin (order is conserved) ```

Example:

sh fd --threads 1 --type file | recursum --threads 10 --digest 64 - > my_checksums.txt

This should be much more efficient, and with better logging, than using --exec or | xargs.

Notes

In mode #1, there is backpressure which minimises wasted RAM (files are only discovered shortly before they're needed). In mode #3, this is not the case because by default, rust cannot use a full pipe buffer as backpressure. If the directory tree is very (very) large, and the files are listed faster than they're hashed (likely), there may be quite some RAM wastage.