Checks whether two files differ
cmp [options] file1 [file2]
The cmp utility does a byte-by-byte comparison of file1 and file2. If the files differ, cmp outputs the location at which the first difference occurs. Unlike diff (page 1149), cmp works with binary as well as ASCII files.
The cmp utility returns an exit status of 0 if the files are the same and 1 if they are different. An exit status > 2 means that an error occurred.
The file1 and file2 arguments identify the two files to compare. If file2 is omitted, cmp uses standard input instead. Using a filename of - for either file1 or file2 causes cmp to read standard input in place of that file.
-i n Skips the first n bytes in both files before beginning ...