This program is useful in determining differences between two files or directories. It produces a list of lines that must be changed (c), appended (a), or deleted (d) to make the first file match the second. Lines from the first file are prefixed by ``<'' and lines from the second are prefixed by ``>''.
The -b option ignores trailing blanks and treats all other strings of blanks as equivalent. The -i option removes case sensitivity so that uppercase and lowercase letters match.