ghashdeep

If you have a large library of files (music, images, videos, etc.), this utility will help you easily calculate or check previously calculated hash sums of the entire library recursively with a single command.

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How to calculate the hash:

If you want to calculate the hash of all files starting from the current directory and recursively for all subdirectories, run this command:

ghashdeep calculate

This command will create a file named "checksum.{md5}" in each file folder, the extension will depend on the checksum algorithm selected, the default is md5.

After running this command, you will see a warning message:

All existing checksums will be replaced with new checksums.
Are you sure? [YES/NO]:

Because if you already have files with calculated checksums, they will be overwritten. If you have never calculated checksums for these files, then type YES in the response and the checksums will be calculated.

For example, if you have a file hierarchy like this:

$ tree
.
├── a
│   └── 1.txt
├── b
│   └── b1
│       └── 2.txt
└── c

After executing the calculate command, you will see the following:

$ tree
.
├── a
│   ├── 1.txt
│   └── checksum.md5
├── b
│   └── b1
│       ├── 2.txt
│       └── checksum.md5
└── c

The resulting checksum.md5 files are fully compatible with the md5sum system utility, so you can manually verify checksums if you wish:

$ md5sum -c checksum.md5
1.txt: OK

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How to validate a hash:

If you have checksum files, you can just run this command and if everything is fine, you will see the following:

$ ghashdeep check
Jul  1 23:08:45.596 INF crawler/check.go:202 Success status=GOOD path=/tmp/mytmp/test folder=a duration=249.231µs
Jul  1 23:08:45.597 INF crawler/check.go:202 Success status=GOOD path=/tmp/mytmp/test/b folder=b1 duration=111.057µs

Invalid checksum:

If some files have changed their checksum, you will see the following message:

$ ghashdeep check
Jul  1 23:11:28.653 ERR crawler/check.go:169 folder have errors status=BAD path=/tmp/mytmp/test folder=a duration=149.804µs
Jul  1 23:11:28.653 ERR crawler/check.go:186 bad checksum status=BAD file=1.txt

This message means that the file named '1.txt' in folder 'a' has an invalid checksum.

File not found:

If a file has been deleted or a new file has been added but does not exist in checksum.md5, you will see these errors:

$ ghashdeep check
Jul  1 23:18:01.588 ERR crawler/check.go:169 folder have errors status=BAD path=/tmp/mytmp/test folder=a duration=104.575µs
Jul  1 23:18:01.588 ERR crawler/check.go:179 no checksum status=BAD file=2.txt
Jul  1 23:18:01.588 ERR crawler/check.go:193 not found status=BAD file=1.txt