File “” it’s the original program, and “” it´s the original program fixed (Other version):

whit “diff” comand,  we compare the two files, and save in “disk_usage.diff” :

diff -u > disk_usage.diff

The “disk_usage.diff” file contend the differences between the files.

When we will apply the changes, usa the “patch” command:

patch < disk_usage.diff

We can see the program file original has been modified.