checksum

Updated: September 28, 2024

Used in verifying downloads. Integrity checking to making sure there was no funny business or corruption.

VERIFY YOUR DOWNLOADS!!

Checksum tools:

sha256sum, sha512sum, md5sum, shasum

These tools work the same.

MANUAL CHECK

sha256sum ubuntu-9.10-dvd-i386.iso    # run while in dir of the file to checksum.
# compare result to corresponding SHA256SUMS file.

shasum -a 256 <file>

SEMI-AUTOMATIC CHECK

First download both SHA256SUMS and SHA256SUMS.gpg

# this will show what key is needed by fail. EFE21092 so key ID = 0xEFE21092 respectively.
gpg --verify SHA256SUMS.gpg SHA256SUMS

# obtain pub key from ubuntu server
gpg --keyserver hkp://keyserver.ubuntu.com --recv-keys 0xFBB75451 0xEFE21092

# verify signature by re-running command used to get IDs
gpg --verify SHA256SUMS.gpg SHA256SUMS

# ubuntu specific auto checksum
sha256sum -c <(grep ubuntu-14.04.1-server-amd64.iso SHA256SUMS)

# generic checksum on any file 
cd <download directory>
sha256sum -c SHA256SUMS 2>&1 | grep OK    # if output says OK then the hashes match.