Checking your CD / DVD ISO images after downloading . . .

By ANTHONIRAJ on January 11th, 2010

Oops , My Fedora dvd is getting struck .

What the hell is this ? why this DVD is not working  properly ?

Oh my God after 9 hours of downloading , I got problem with DVD .

Everyone could have murmured or shouted these words them self while they are facing some problem with installing ISO images. Last week  i downloaded Fedora 12 DVD -3.0 GB. but i got problem with installation due to corrupted media . I spent one day for downloading that iso image , i dont know why this iso image get corrupted . any way i tried to find the answer .  Finally i found some tips and tricks with downloading ISO images.

Reason for corrupted ISO images

  1. Download Interruption or incomplete download – Use proper download manager or accelerator for downloading ISO images.
  2. The ISO image might be corrupted while burning with high speed . So use 2x /4x speed in your burning application to avoid this problem
  3. Forget to check with hash code  – All ISO images comes with some hash code for checking its content . user need to check after download it.

Checking ISO images using SHA1SUM or MD5SUM

The first two problem could be easily solved using download manager and setting burning speed . here some information about checking ISO image has been given for Linux users

  • Download ISO images , For example :  Fedora-12-i386-DVD.iso
  • Download the MD5SUM or SHA1SUM hash keys from fedora website – Save the second line into one text file [check.txt]
Hash: SHA1
f0ad929cd259957e160ea442eb80986b5f01daaffdbcc7e5a1840a666c4447c7 *Fedora-12-i386-DVD.iso
  • Now use sha1sum or md51sum command for checking your ISO image . In terminal type the following command

# sha1sum    -c check.txt

or

# md5sum    -c check.txt

  • If the file has no error then the output of above commands would be

Fedora-12-i386-DVD.iso: OK

  • Else some error message would be displayed .

Note : The format of the checksum file is so important , it has to be like

<checksum value><TWO WHITESPACES><name of file to be checked>

In our case , the check.txt sould have

f0ad929cd259957e160ea442eb80986b5f01daaffdbcc7e5a1840a666c4447c7  Fedora-12-i386-DVD.iso

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