After downloading an .iso
file from ubuntu.com (please tick the box under the “Start Download” green button if you want the alternate version and choose a mirror close to your location), you need to verify that the .iso
file is not corrupted before you can use it to install Ubuntu.
Ubuntu provides the md5 hashes of all the released .iso
files. Please read here for more information about md5 (Message-Digest algorithm 5). To check the file, we’ll use md5sum.
- md5sum on the downloaded file
Go to the directory the file is located and runmd5sum
. In the example below, I had downloaded the file to the desktop::~ $cd Desktop/ :~/Desktop $ md5sum ubuntu-7.10-alternate-i386.iso 9a4ae3cfd68911a861d094ec834c9b48 ubuntu-7.10-alternate-i386.iso
Then verify it matches the hash from the Ubuntu release.
- md5sum on the burnt file
Once you have burnt the.iso
file to a CD, it is a good idea to check it too, and verify nothing happened during the process. By default, Ubuntu mounts the cdrom to /media::~ $ cd /media/cdrom0/ :/media/cdrom0 $ md5sum -c md5sum.txt | grep -v 'OK$' :/media/cdrom0 $
If the match is good, there will be no error on the output.
You can then use the disk to install Ubuntu :)
Reference
Shamelessly inspired from the Ubuntu Community Documentation page. Please refer to this page if you are downloading and burning the .iso
file on Windows.
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hi,
To check the downloaded file, it’s also a good solution to download the ubuntu MD5SUM file (which contains all iso md5 hash) in the same place and do:
md5sum -c MD5SUM
That will compare the two hashes for you (and output OK or FAILED)
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