zip, zipcloak, zipnote, zipsplit ソース
zip is a compression and file packaging utility for Unix,
VMS, MSDOS, OS/2, Windows NT, Minix, Atari and Macintosh.
It is analogous to a combination of the UNIX commands tar(1)
and compress(1) and is compatible with PKZIP (Phil Katz's
ZIP for MSDOS systems).