replace/modify tail of a gz file with gzip.open
Not possible - you can not replace parts of a compressed file without decompressing it first. At least not with the common compression algorithms.
I have a gz file that with a huge size, is it possible to replace the tail without touching the rest of the file? I tried gzip.open( filePath, mode = 'r+' ) but the write method was blocked .... saying it is a read-only object ... any idea? 
what I am doing now is... gzip.open as r and once I get the offset of the start of the tail, I close it and re-open it with gzip.open as a and seek (offset)... which is not likely the best idea 
thanks 
John