The intersection and set difference (A-B) on text files

Intersection and set difference operations are commonly used in mathematical classes on set theory. However, similar operations on strings are also very helpful in some scenarios.

Getting ready

The comm command is a utility to perform a comparison between the two files. It has many good options to arrange the output in such a way that we can perform intersection, difference, and set difference operations.

• Intersection: The intersection operation will print the lines that the specified files have in common with one another

• Difference: The difference operation will print the lines that the specified files contain and that are not the same in all of those files

• Set difference: The set difference operation will print the lines in file "A" that do not match those in all of the set of files specified ("B" plus "C" for example)

How to do it...

Note that comm takes only sorted files as input. Take a look at the following example:

$ cat A.txt
apple...