Updated: 07/12/2017 by Computer Hope

Md5sum is a software utility used to check the integrity of an ISO image before the file is used to create a CD (compact disc). Computers running Linux have this utility installed on their default system. Users of other operating systems may need to download an md5sum utility before being able to check the integrity.

How to use md5sum

In Linux, run md5sum with the name of a file, as shown below, to calculate and display the MD5 hash.

md5sum ubuntu-14.04.1-desktop-i386.iso

The output shows the md5 hash, and the name of the file hashed:

a4fc15313ef2a516bfbf83ce44281535 ubuntu-14.04.1-desktop-i386.iso

Once you have gathered the hash, you can compare it with the hash information from where you downloaded the .iso file. In our example, we have an Ubuntu .iso file. The MD5 hash information is listed in the UbuntuHashes overview. If the MD5 does not match the file, it is either incomplete, been changed, or is otherwise compromised.


Microsoft Windows users can use the fciv command line program from Microsoft to get the MD5 and SHA-1 information from a file.

CD terms, Hashing, ISO image