Compares the contents of two files. If the files are different, then cmp returns the byte posititon and line number of the first difference between the two files. If there is no difference, then cmp returns nothing. The cmp command works on all files not just text files. Other similar commands such as comm and diff only work with text files. Example: cmp my.report my.file If there was a difference in the files the output would look something like my.report my.file differ: char 56, line 3 You can use the -l switch to have it show all the differences between two files.