Thread: SHA-256?
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Old 10th March 2012
AnilG AnilG is offline
Real Name: Anil Gee
Port Guard
Join Date: Sep 2010
Location: Sydney Australia
Posts: 20

I just wish someone had shared an example command line to do an actual checksum confirmation. I spent quite a few minutes working this one out. I think the man page synopsis may be wrong or inaccurate, and it doesn't mention exit status quietly used to confirm check. Also, big files take a small while to check so you can't do too many tests quickly and not sure if it's actually hung or waiting for input. I tried pipeing file into the command as well at one point.

On Mac OS X 10.6 Snow Leopard checking a FreeBSD SHA256 checksum.
I've downloaded a 2.1 GB ISO file and the checksums are provided inside a file called CHECKSUM.SHA256 (there's an MD5 list of checksums too).

$ grep dvd CHECKSUM.SHA256
SHA256 (FreeBSD-9.0-RELEASE-i386-dvd1.iso) = ebc75ecdbd0580fbe9e59373962e0fc452c4480082af563e5c d765aca1ecd705

$ /usr/bin/shasum -a 256 FreeBSD-9.0-RELEASE-i386-dvd1.iso
ebc75ecdbd0580fbe9e59373962e0fc452c4480082af563e5c d765aca1ecd705 FreeBSD-9.0-RELEASE-i386-dvd1.iso

$ /usr/bin/shasum -a 256 -c CHECKSUM.SHA256 FreeBSD-9.0-RELEASE-i386-dvd1.iso
$ echo $?
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