сравнить два файла (compare two files)
Использование в приложениях (Application usage)
If lines at the end of a file are changed and other lines are
added, diff output may show this as a delete and add, as a
change, or as a change and add; diff is not expected to know
which happened and users should not care about the difference in
output as long as it clearly shows the differences between the
files.
