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压缩解压,是unzip540的升级,这个外国网站摘来的源码,是evb编写.

Acorn-specific usage instructions
---------------------------------

As zipfiles can come from a variety of sources apart from Acorn machines,
consideration had to be given to the handling of dot-extensions, e.g.
"DOSFILE.TXT", "unix-filename.tar.gz". These are extracted as "DOSFILE/TXT"
and "unix-filename/tar/gz"; their names may or may not be truncated,
depending on where the files are being created: what filing system and, for
Filecore-based filing systems such as ADFS or an IDEFS or SCSIFS, which
disk/partition format (names will not be truncated if you're using E+ or F+).

Where truncation occurs, you must be REALLY careful about extracting files
from archives. The files

    dummy_source.c and dummy_source.h

will both be extracted as

    dummy_sour

UnZip will prompt you for confirmation of the over-writing of these files,
but you must be really careful unless you wish to lose files! Also, because
UnZip is a unix-ported program, the filenames are CASE SENSITIVE.

    *unzip new/zip newfile

will extract 'newfile', but not 'NewFile', 'NEWFILE' or any other
combinations. However, you can use the -C option to force operations to
disregard the case of filenames.

The Acorn UnZip port has an additional feature to cope with the extraction of
files containing 'c' code. As you may be aware, Acorn Desktop C requires all
files called "foo.c" to be renamed to "c.foo", ie "foo" in a directory called
"c".

There are two ways of using this feature.

- The old way: use a colon-separated environment variable named "Unzip$Exts".

  Any extensions found in this variable will be extracted to directories
  named after the extension, with the extension stripped. For example:

    *Set Unzip$Exts "c:h:o:s"
    *unzip foo/zip

- The new way: use the -/ option. For example:

  Any extensions found in the parameter for this option will be extracted to
  directories named after the extension, with the extension stripped. For
  example:

    *unzip -/c:h:o:s foo/zip

If foo/zip contains a file named "foo.c", this file will be written as "foo"
in directory "c". This can be used to include "c:h:o:s:txt" to pull all the
text files out to a separate directory.

UnZip fully supports SparkFS Extra Field. This means that zipfiles created
with SparkFS or Zip (on RISC OS) will be correctly unzipped, including
filetypes.

UnZipSFX can be used to create self-extracting archives. To use it, just
create a common zipfile using Zip (or SparkFS), then load the UnZipSFX
executable into an editor (eg. Edit, Zap), go with the caret the end of the
file (using CTRL-CursorDown) and drag the zipfile to the editor window (in
other words, append the zipfile to the UnZipSFX executable). Now, saving the
resulting file (with filetype Absolute (&FF8)), you have a self-extracting
archive (ie. double-clicking on it will unzip the contents of the original
zipfile to the currently selected directory).