Not withstanding afoken's very good points above, the OP is combining his random number with part of the original filename.

I was suggesting he do the same with the MD5, which covers the possibility of there being two copies of the same content under different names in the same directory.

I would also combine the file length into the derived number, as probabilistically, each MD5 will repeat once in each set of files of length modulus 16.

In reply to Re^3: Renaming an image file by BrowserUk
in thread Renaming an image file by Anonymous Monk

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