Checksum Verification

Have you ever wondered what to do with the provided checksums that site give for their Linux ISO images? Those checksums are basically a way to prove that the file hasn’t been tampered with. Here is how I use them to check every ISO I download.

echo "<checksum-here>  <file-name>" | shasum -a 256 --check

• The -a 256 argument specifies what algorithm to use. Eg. SHA 256 or SHA 512
• The –check argument tells shasum to take the info from echo as input and compares it with the actual sum.
• There are two spaces between the checksum and the file name.

<file-name>: OK

<file-name>: FAILED
shasum: WARNING: 1 computed checksum did NOT match