One of the most common ways of determining if two files are identical (assuming their sizes match) is using a program to create a " hash " (essentially a fingerprint) of a file. The most common ones are md5sum and sha1sum . For example: $ md5sum file1 file2 e0e7485b678a538c2815132de7f9e878 file1 4a14aace18d472709ccae3910af55955