Kevin Warrington

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Verifying Data Using Checksums

Checksums are used verify data integrity and in some cases, authenticity.

It is especially important to run checksums on large files, such as operating systems, where 100% completeness is desired. As file size increases, so will the possibility of errors during transmission.

To check a single file on Mac OS X, simply run:

shasum -a 256 file.iso

To check multiple files using a SHA256SUMS file:

cd ~/Downloads
shasum -a 256 -c 1.4.3_SHA256SUMS 2>&1 | grep OK

If the file was verified you should see:

Vagrant-1.4.3.dmg: OK