Difference between revisions of "Check a Downloaded ISO Image For Errors"

Prior to burning your downloaded ISO image (or using it as a virtual disc in Virtualbox), it is '''strongly''' recommended that you first check that it hasn't been corrupted. The consequences of not doing so, especially if you intend on installing Manjaro as your main operating system, should be obvious, that is that a corrupted image will result in a corrupted installation.  

To make the check, you must first download the appropriate ''checksum file'' from the same ''Sourceforge'' website folder as your chosen ISO image. A checksum file will have the same name as the ISO image that it is to be used with; the only difference is that it will end in either '''-sha1.sum''' or '''-sha256.sum'''. For example, the appropriate checksum files for the ''manjaro-xfce-0.8.1-x86_64.iso'' file (64 bit Manjaro release 0.8.1 with the XFCE desktop) would be:  

The 'sha' part of the checksum file name stands for <u>S</u>ecure <u>H</u>ash <u>A</u>lgorithm. This algorithm is used to generate a particular code unique to the downloaded ISO image. '''sha1''' and '''sha256''' are different versions of the algorithm that you can use to do this. Whilst sha1 is the most commonly used version, sha256 is a later and more secure version. Whichever you decide to use is entirely your choice. '''However, if you are unsure, then it is recommended to use sha256'''.

The checksum file itself is just a text document that contains a code that should match the code generated by the sha1 or sha256 algorithm. As such, if the code generated from the ISO file matches that contained in the checkum file, then the ISO is fine; otherwise, if the two codes don't match then it means that the ISO file has changed in some way, most likely due to being corrupted. You can think of it like someone using a secret password to identify who they are: if they provide the wrong password, then something is obviously amiss!