Rhash is a command-line utility for computing hash sums of files. It supports a wide range of hashing algorithms including MD5, SHA1, SHA256, CRC32, and many others. This tool is invaluable for verifying file integrity, ensuring that files have not been altered during transfer or storage.

Compute SHA256 Hash

To compute the SHA256 hash for a file and store the checksum in a separate file, use the following command:

# utility for computing hash sums https://sf.net/p/rhash/

# compute sha256 for a file and store checksum in a file:
rhash --sha256 file.txt > file.sha256

Verify File Checksums

You can verify the integrity of one or more files against a checksum file using the -c option:

# verify the file(s):
rhash -c file.sha256

Generate Recursive Hash Files

To generate a SHA256 hash file for all files within a directory and its subdirectories, use the -r flag:

# Generate a SHA256 hash file for all files in a directory tree:
rhash -r --sha256 directory/ > directory.sha256

Verify Recursive Checksums

To verify all checksum files within a directory tree, including specific algorithms like SHA256, you can combine the -c and -r flags:

# Verify all .sha256 files in a directory tree:
rhash -cr --crc-accept=sha256 directory/

Additional Hashing Algorithms

Rhash supports numerous other hashing algorithms. For a full list and more advanced options, please refer to the official Rhash documentation.

External Resources:

• Rhash Official Website
• Cryptographic Hash Function - Wikipedia
• Web Crypto API - MDN Web Docs (for browser-based hashing)