Loops And Such Options

[bam]

I have this so far:

CODE

for item in dupes[]:
  mydupeitem=item
  for item in filter[]:
     if mydupeitem[2:] = item:
        pass
     else
        write......etc.

now is there anything wrong with this? it wipes out my entire bash history, so it never gets to the write statement. filter[] is just a list of filters(strings) and dupes[] is just a list of strings as well, basically i an 'cleaning' my bash history at logoff, I have a remove duplicates script running and it sorts but I would like to remove any "cd blahblah" and rm's mv's etc. any ideas, I am new to python, so any help would be great.