Sample input lines do not need to be actual data; they just need to provide representative data.
Are these text files (no null bytes and a <newline> character at the end of each line) or are they binary files (may contain null bytes, for example in floating point numeric constants, and record length is determined by byte count only instead of containing a line terminating character sequence)?
What codeset is used to encode data in these files? (Perhaps ASCII, ISO-8859-1, UTF-8, or EBCDIC?)
In your 1st post in this thread, you said:
If you want a log (in addition to an output file that is a modified version of the input file), exactly what do you want logged? Please show us a sample of what a log should look like for a particular set of representative sample input records.
Please help us help you. Don't make us guess at everything that will determine what tools can be used to process your data to get the results you want! Making us guess at everything wastes the time of anyone who wants to help you, is likely to get you suggestions that don't stand a chance of working with your real data, and makes it much less likely that you will get any suggestions that work in your environment.