CheckSame

CheckSame is a recursive, cumulative Blake3 file hasher for x86-64 Linux machines.

It is "cumulative" in the sense that it computes a single hash representing all of the files passed to it, rather than individual hashes for each file.

By default, this hash is simply printed to STDOUT.

However, when run with -c or --cache, the resulting hash will be stored and compared against the previous run. In this mode, the program will output one of:

Value	Meaning
-1	No hash was previously stored.
0	No change detected.
1	Something changed.

The cache mode is primarily intended to provide an efficient bypass for expensive build routines, or as a way to quickly see if a directory's contents have changed (beyond mere timestamp updates).

The cache lives in /tmp/checksame and can be cleared by running the program with the --reset flag, or simply deleting the files in that directory. On most systems, that directory should disappear automatically on reboot.

Installation

Debian and Ubuntu users can just grab the pre-built .deb package from the latest release.

This application is written in Rust and can alternatively be built from source using Cargo:

# Clone the source.
git clone https://github.com/Blobfolio/checksame.git

# Go to it.
cd checksame

# Build as usual. Specify additional flags as desired.
cargo build \
    --bin checksame \
    --release

(This should work under other 64-bit Unix environments too, like MacOS.)

Usage

It's easy. Just run checksame [FLAGS] [OPTIONS] <PATH(S)>….

The following flags and options are available:

Short	Long	Value	Description
`-c`	`--cache`		Cache the hash and output the status.
`-h`	`--help`		Print help information and exit.
`-l`	`--list`	`<FILE>`	Read (absolute) file and/or directory paths to checksum from this text file — or STDIN if "-" — one entry per line, instead of or in addition to `<PATH(S)>`.
	`--reset`		Reset any previously-saved hash keys before starting.
`-V`	`--version`		Print program version and exit.

For example:

# Generate checksum by passing any number of file and directory paths.
# You can also place paths in a text file — one per line — and add
# that to the mix with the -l option.
checksame -l /path/to/list.txt /path/to/app.js /path/to/folder

# Avoid doing something expensive if nothing changed.
[ "$( checksame -c -l /path/list.txt )" = "0" ] || ./expensive-task

License

See also: CREDITS.md

This work is free. You can redistribute it and/or modify it under the terms of the Do What The Fuck You Want To Public License, Version 2.

DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
Version 2, December 2004

Copyright (C) 2004 Sam Hocevar <sam@hocevar.net>

Everyone is permitted to copy and distribute verbatim or modified
copies of this license document, and changing it is allowed as long
as the name is changed.

DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

0. You just DO WHAT THE FUCK YOU WANT TO.