The logic you need is, in pseudo code 
while there's a next line
    extract the ID
    check if ID matches the previous ID
    if not:
       set previous ID to current ID
       increment a counter
       if counter > 100
            close current output file
            open a new output file
            reset counter
    
    write the line to the current output file.

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Try to write that in perl you can almost translate it directly. If you have troubles with a specific step, shows us what you've tried and where your problem is.

In reply to Re: Help spliting file into chunks by moritz
in thread Help spliting file into chunks by mmittiga17

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