I'm fully familiar of what packed decimal and zoned decimal are. But knowing how to interpret fields encoded in those formats if you don't know record boundaries and field boundaries is a wild guessing game.

I didn't know that a copybook was another language's name for what the C language calls an include file (thank you jgt).

Fortunately, I haven't had to use COBOL since 1975. I'm also fully aware that the UNIX dd utility was a joke showing how versatile UNIX utilities were and could even be made to use operands that were familiar to programmers used to writing IBM System 360 Job Control Language (JCL) card decks instead of all of the supposedly "confusing" single letter utility options used on most UNIX utilities. If you've never written JCL, the JCL DD statements described where various input and output files were to be found and/or placed for whatever job was to be run by that JCL deck and, especially if the file resided on a magnetic tape, the size of the blocks that were to be read from or written to the device used to access that file. Unfortunately (or fortunately, depending on how much you like JCL), the utility proved very useful when transferring files between UNIX systems and mainframes and we're still stuck with that syntax today.

But enough of this digression.

swapna_1990 has a file containing some EBCDIC text and some packed decimal, zoned decimal, or other binary data mixed in and wants it converted to ASCII text and "normal data" that is readable. Whether that data comes from a mainframe or from a C program written on a UNIX, Linux, or BSD system doesn't really matter. If you don't know the format of the data you're reading including field lengths or separators, field types, and record lengths or separators; then you don't know how to process that data. Until we get the data format from swapna_1990's customer, there is nothing we can do to guess at how that data could be extracted nor what tools might need to be used to do so. The fact that it came from a mainframe makes a COBOL program an obvious guess at something that might work. But from what we know so far, if swapna_1990 is extremely lucky, it is possible that a dd command coupled with output piped through some awk code might be able to work wonders. (Not highly likely, but there is a chance.)