Test to see if file exists


I am building a user interface and I need to save 3 files (and sometimes 4 files) when the user chooses save. To keep the name taxonomy constant, I need to constrain the choices and locations. In general it is working as expected, but I have the case when the user inadvertently chooses a name already used. The /O flag in save would cause the data to be overwritten which I do not want, however without the /O flag the user is presented with multiple save dialogs and is rightly confused. Is there a simple way to test for an existing file? The directory currently has 600+ files and growing and I am loath to do an indexed file search on every save. Is there the equivalent of a waveExists function for files?