anybody know how to disallow the function crypt from adding the '/' (forward slash) to a word that it encrypts??

The short answer is that you can't  

The crypt function is used to encode passwords using the DES algorithm.  This takes the word that you want to encode, plus a 2 character "salt" and produces a 13 character string which may contain the 64 characters A to Z a to z 0 to 9 . (period) and / (forward slash).

Are you by any chance using the encoded string as a file name?   If so, you could substitute any / characters you get in the encoding to something else - foe example _ or - (underscore or hyphen):
     $encoded = crypt($plaintext,$salt)
     $encoded =~ s!/!_!g;

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