readme

压缩算法的源代码

vms/README for UnZip 5.12 and later, 25 Aug 94
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Notes about using UnZip and zipfiles under VMS (see INSTALL for instructions
on compiling):

 - Install UnZip as foreign symbol by adding this to login.com:
      $ unzip == "$disk:[dir]unzip.exe"
      $ zipinfo == "$disk:[dir]unzip.exe -Z"
   where "disk" and "dir" are location of UnZip executable; the "$" before
   the disk name is important.  Some people, including the author, prefer
   a short alias such as "ii" instead of "zipinfo"; edit to taste.

 - Optionally install UnZipSFX for use with the MAKESFX.COM command file:
      $ unzipsfx :== disk:[dir]unzipsfx.exe
   Thereafter an archive "foo.zip" may be converted to "foo.exe" simply by
   typing "@makesfx foo" (assuming MAKESFX.COM is in the current directory).
   Note that there is *no* leading "$" in this case.

 - After proper installation, the default version of UnZip is invoked just
   as in Unix or MS-DOS:  "unzip -opts archive files".  The hyphen ('-') is
   the switch character, not the slash ('/') as in native VMS commands.  An
   alternative is available if VMSCLI is defined during compilation; this
   version does provide a native VMS-style command interface (e.g., /ZIPINFO
   instead of -Z).  Both versions accept the command "unzip -v", which can
   be used to check whether VMSCLI was defined or not; but an even simpler
   method is to type "unzip" and look at the help screen.  Note that options
   placed in an environment variable (UNZIP_OPTS) must be of the short, hy-
   phenated form regardless of how UnZip was compiled.

 - VMS (or the C compiler) translates all command-line text to lowercase
   unless it is quoted, making some options and/or filenames not work as
   intended.  For example:
	unzip -V zipfile vms/README
   is tranlated to
	unzip -v zipfile vms/readme
   which may not match the contents of the zipfile and definitely won't
   extract the file with its version number as intended.  This can be
   avoided by use of the -C option (/CASE_INSENSITIVE) or by enclosing
   the uppercase stuff in quotes:
	unzip "-V" zipfile "vms/README"
   Note that quoting the whole line probably won't work, since it would
   be interpreted as a single argument by the C library.

 - Wildcards which refer to files internal to the archive behave like Unix
   wildcards, not VMS ones (assuming UnZip was not compiled with VMSWILD
   defined).  This is both a matter of consistency (see above) and power--
   full Unix regular expressions are supported, so that one can specify
   "all .c and .h files which start with a, b, c or d and do not have a 2
   before the dot" as "[a-d]*[^2].[ch]".  Of course, "*.[ch]" is a much more
   common wildcard specification, but the power is there if you need it.
   Note that "*" matches zipfile directory separators ('/'), too.  If UnZip
   *was* compiled with VMSWILD defined (do "unzip -v" to check), the single-
   character wildcard is "%" rather than "?", and character sets (ranges)
   are delimited with () instead of [] (for example, "*.(ch)").

 - Created files get whatever permissions were stored in the archive (mapped
   to VMS and/or masked with your default permissions, depending on the 
   originating operating system), but created directories additionally in-
   herit the (possibly more restrictive) permissions of the parent directory.
   And obviously things won't work if you don't have permission to write to
   the extraction directory.

 - When transferring files, particularly via Kermit, pay attention to the
   settings!  In particular, zipfiles must be transferred in some binary
   mode, which is NOT Kermit's default mode, and this mode must usually be
   set on BOTH sides of the transfer (e.g., both VAX and PC).  See the notes
   below for details.




From Info-ZIP Digest (Wed, 6 Nov 1991), Volume 91, Issue 290:

   Date: Tue, 5 Nov 91 15:31 CDT
   From: Hugh Schmidt <[e-mail]>

            ****************************************************
            *** VMS ZIP and PKZIP compatibility using KERMIT ***
            ****************************************************

   Many use Procomm's kermit to transfer zipped files between PC and VMS
   VAX.  The following VMS kermit settings make VMS Zip/UnZip compatible
   with PC Zip/UnZip or PKZIP/PKUNZIP:
                                         VMS kermit          Procomm kermit
                                    -------------------   --------------------
   Uploading PC zipfile to VMS:     set file type fixed   set file type binary
   Downloading VMS zipfile to PC:   set file type block   set file type binary

   "Block I/O lets you bypass the VMS RMS record-processing capabilities
   entirely", (Guide to VMS file applications, Section 8.5).  The kermit
   guys must have known this!