GZIP header format (.gz extention)
gzip file format 참조URL : (http://www.gzip.org/zlib/rfc-gzip.html#file-format) [GZIP 구조 요약]+---+---+---+---+---+---+---+---+---+---+|ID1|ID2|CM |FLG| MTIME |XFL|OS | (more-->)+---+---+---+---+---+---+---+---+---+---+●(if FLG.FEXTRA set)+---+---+=================================+| XLEN |...XLEN bytes of "extra field"...| (more-->)+---+---+=================================+●(if FLG.FNAME set)+=====..