unzip.doc

完整的解压zip文件的源码。包含密码功能

              data.

       -J     [MacOS only] ignore MacOS extra fields.  All Macin-
              tosh  specific  info  is  skipped.  Data-fork   and
              resource-fork are restored as separate files.

       -L     convert to lowercase any filename originating on an
              uppercase-only operating  system  or  file  system.
              (This  was  unzip's  default  behavior  in releases
              prior to 5.11; the new default behavior is  identi-
              cal  to  the old behavior with the -U option, which
              is now obsolete and will be  removed  in  a  future
              release.)    Depending   on   the  archiver,  files
              archived under single-case file systems  (VMS,  old
              MS-DOS  FAT,  etc.)  may be stored as all-uppercase
              names;  this  can  be  ugly  or  inconvenient  when
              extracting to a case-preserving file system such as
              OS/2 HPFS or a case-sensitive  one  such  as  under
              Unix.   By  default  unzip  lists and extracts such
              filenames  exactly  as  they're  stored  (excepting
              truncation,  conversion  of unsupported characters,
              etc.); this option causes the names  of  all  files
              from  certain systems to be converted to lowercase.

       -M     pipe all output through an internal  pager  similar
              to  the  Unixmore(1)  command.   At  the  end  of a
              screenful  of   output,   unzip   pauses   with   a
              ``--More--''  prompt;  the  next  screenful  may be
              viewed by pressing the Enter (Return)  key  or  the
              space bar.  unzip can be terminated by pressing the
              ``q'' key and, on some  systems,  the  Enter/Return
              key.   Unlike  Unix  more(1),  there is no forward-
              searching  or  editing  capability.   Also,   unzip
              doesn't  notice  if  long lines wrap at the edge of
              the screen, effectively resulting in  the  printing
              of  two  or more lines and the likelihood that some
              text will scroll off the top of the  screen  before

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UNZIP(1L)                                               UNZIP(1L)

              being viewed.  On some systems the number of avail-
              able lines on the screen is not detected, in  which
              case unzip assumes the height is 24 lines.

       -n     never  overwrite existing files.  If a file already
              exists, skip the extraction of  that  file  without
              prompting.    By   default   unzip  queries  before
              extracting any file that already exists;  the  user
              may  choose  to  overwrite  only  the current file,
              overwrite all files, skip extraction of the current
              file,  skip  extraction  of  all existing files, or
              rename the current file.

       -N     [Amiga] extract file comments as  Amiga  filenotes.
              File  comments  are  created  with the -c option of
              zip(1L), or with the -N option of the Amiga port of
              zip(1L), which stores filenotes as comments.

       -o     overwrite  existing  files without prompting.  This
              is a dangerous option, so use it with care.  (It is
              often used with -f, however, and is the only way to
              overwrite directory EAs under OS/2.)

       -P password
              use password to decrypt encrypted  zipfile  entries
              (if any).  THIS IS INSECURE!  Many multi-user oper-
              ating systems provide ways for any user to see  the
              current  command  line  of  any other user; even on
              stand-alone systems there is always the  threat  of
              over-the-shoulder  peeking.   Storing the plaintext
              password as part of a command line in an  automated
              script  is  even worse.  Whenever possible, use the
              non-echoing, interactive prompt to enter passwords.
              (And  where security is truly important, use strong
              encryption such as Pretty Good Privacy  instead  of
              the relatively weak encryption provided by standard
              zipfile utilities.)

       -q     perform operations quietly (-qq  =  even  quieter).
              Ordinarily unzip prints the names of the files it's
              extracting or testing, the extraction methods,  any
              file  or zipfile comments that may be stored in the
              archive, and possibly a summary when finished  with
              each  archive.   The  -q[q]  options  suppress  the
              printing of some or all of these messages.

       -s     [OS/2, NT, MS-DOS] convert spaces in  filenames  to
              underscores.   Since all PC operating systems allow
              spaces in  filenames,  unzip  by  default  extracts
              filenames     with     spaces     intact     (e.g.,
              ``EA DATA. SF'').  This can  be  awkward,  however,
              since MS-DOS in particular does not gracefully sup-
              port spaces in filenames.  Conversion of spaces  to

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UNZIP(1L)                                               UNZIP(1L)

              underscores  can  eliminate the awkwardness in some
              cases.

       -U     (obsolete; to be removed in a future release) leave
              filenames  uppercase  if created under MS-DOS, VMS,
              etc.  See -L above.

       -V     retain (VMS) file version numbers.  VMS  files  can
              be  stored  with  a  version  number, in the format
              file.ext;##.  By default the ``;##''  version  num-
              bers  are  stripped, but this option allows them to
              be retained.  (On file systems that limit filenames
              to  particularly short lengths, the version numbers
              may be truncated or  stripped  regardless  of  this
              option.)

       -X     [VMS, Unix, OS/2, NT] restore owner/protection info
              (UICs) under VMS, or user and group info  (UID/GID)
              under  Unix,  or  access control lists (ACLs) under
              certain  network-enabled  versions  of  OS/2  (Warp
              Server  with  IBM  LAN Server/Requester 3.0 to 5.0;
              Warp Connect with IBM Peer 1.0), or  security  ACLs
              under  Windows NT.  In most cases this will require
              special system privileges, and doubling the  option
              (-XX)  under  NT  instructs unzip to use privileges
              for extraction; but under Unix, for example, a user
              who  belongs  to  several  groups can restore files
              owned by any of those groups, as long as  the  user
              IDs  match his or her own.  Note that ordinary file
              attributes are always restored--this option applies
              only to optional, extra ownership info available on
              some operating systems.  [NT's access control lists
              do  not  appear  to  be  especially compatible with
              OS/2's, so no attempt  is  made  at  cross-platform
              portability  of access privileges.  It is not clear
              under what conditions this  would  ever  be  useful
              anyway.]

       -$     [MS-DOS,  OS/2, NT] restore the volume label if the
              extraction medium is removable (e.g., a  diskette).
              Doubling  the option (-$$) allows fixed media (hard
              disks) to be labelled as well.  By default,  volume
              labels are ignored.

ENVIRONMENT OPTIONS
       unzip's  default  behavior  may  be  modified  via options
       placed in an environment variable.  This can be done  with
       any  option,  but  it is probably most useful with the -a,
       -L, -C, -q, -o, or -n modifiers:  make unzip  auto-convert
       text  files  by  default,  make  it convert filenames from
       uppercase systems to lowercase, make it match names  case-
       insensitively,  make  it  quieter, or make it always over-
       write or never overwrite files as it extracts  them.   For
       example,  to  make  unzip act as quietly as possible, only

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UNZIP(1L)                                               UNZIP(1L)

       reporting errors, one would use one of the following  com-
       mands:

           UNZIP=-qq; export UNZIP    Unix Bourne shell
           setenv UNZIP -qq           Unix C shell
           set UNZIP=-qq              OS/2 or MS-DOS
           define UNZIP_OPTS "-qq"    VMS (quotes for lowercase)

       Environment  options are, in effect, considered to be just
       like any other command-line options, except that they  are
       effectively  the  first  options  on the command line.  To
       override an environment option, one may  use  the  ``minus
       operator'' to remove it.  For instance, to override one of
       the quiet-flags in the example above, use the command

           unzip --q[other options] zipfile

       The first hyphen is the normal switch character,  and  the
       second  is a minus sign, acting on the q option.  Thus the
       effect here is to cancel one  quantum  of  quietness.   To
       cancel  both  quiet  flags,  two  (or more) minuses may be
       used:

           unzip -t--q zipfile
           unzip ---qt zipfile

       (the two are equivalent).  This may seem awkward  or  con-
       fusing,  but  it is reasonably intuitive:  just ignore the
       first hyphen and go from there.   It  is  also  consistent
       with the behavior of Unix nice(1).

       As  suggested  by the examples above, the default variable
       names are UNZIP_OPTS for VMS (where  the  symbol  used  to
       install unzip as a foreign command would otherwise be con-
       fused with the environment variable), and  UNZIP  for  all
       other  operating systems.  For compatibility with zip(1L),
       UNZIPOPT is also accepted (don't ask).  If both UNZIP  and
       UNZIPOPT  are  defined,  however,  UNZIP takes precedence.
       unzip's diagnostic option (-v with no zipfile name) can be
       used  to  check  the values of all four possible unzip and
       zipinfo environment variables.

       The timezone variable (TZ) should be set according to  the
       local  timezone in order for the -f and -u to operate cor-
       rectly.  See the description  of  -f  above  for  details.
       This  variable  may  also be necessary in order for times-
       tamps on extracted files to be set correctly.  Under  Win-
       dows  95/NT unzip should know the correct timezone even if
       TZ is unset, assuming the timezone is correctly set in the
       Control Panel.

DECRYPTION
       Encrypted  archives  are fully supported by Info-ZIP soft-
       ware, but due to United States  export  restrictions,  the

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UNZIP(1L)                                               UNZIP(1L)

       encryption  and  decryption  sources are not packaged with
       the regular unzip and zip distributions.  Since the  crypt
       sources  were  written  by  Europeans,  however,  they are
       freely available at sites throughout the  world;  see  the
       file  ``WHERE'' in any Info-ZIP source or binary distribu-
       tion for locations both inside and outside the US.

       Because of the separate  distribution,  not  all  compiled
       versions  of unzip support decryption.  To check a version
       for crypt support, either attempt to test  or  extract  an
       encrypted archive, or else check unzip's diagnostic screen
       (see the -v option above) for ``[decryption]'' as  one  of
       the special compilation options.

       As  noted  above,  the  -P  option may be used to supply a
       password on the command line, but at a cost  in  security.
       The  preferred decryption method is simply to extract nor-
       mally; if a zipfile member is encrypted, unzip will prompt
       for  the  password  without  echoing what is typed.  unzip
       continues to use the same password as long as  it  appears
       to  be  valid,  by  testing a 12-byte header on each file.
       The correct password will always  check  out  against  the
       header,  but  there is a 1-in-256 chance that an incorrect
       password will as well.  (This is a security feature of the
       PKWARE   zipfile  format;  it  helps  prevent  brute-force
       attacks that might otherwise gain a large speed  advantage
       by  testing  only the header.)  In the case that an incor-
       rect password is given but it passes the header test  any-
       way,  either  an  incorrect  CRC will be generated for the
       extracted data or else unzip will fail during the  extrac-
       tion  because  the ``decrypted'' bytes do not constitute a
       valid compressed data stream.

       If the first password fails the header check on some file,
       unzip  will  prompt  for another password, and so on until
       all files are extracted.  If  a  password  is  not  known,
       entering  a null password (that is, just a carriage return
       or ``Enter'') is taken as a signal  to  skip  all  further
       prompting.   Only unencrypted files in the archive(s) will
       thereafter be extracted.  (In fact, that's not quite true;
       older  versions  of  zip(1L) and zipcloak(1L) allowed null
       passwords, so unzip checks each encrypted file to  see  if
       the null password works.  This may result in ``false posi-
       tives'' and extraction errors, as noted above.)

       Archives encrypted  with  8-bit  passwords  (for  example,
       passwords  with  accented  European characters) may not be
       portable across  systems  and/or  other  archivers.   This
       problem  stems  from  the use of multiple encoding methods
       for such characters, including Latin-1  (ISO  8859-1)  and
       OEM  code  page  850.   DOS  PKZIP 2.04g uses the OEM code
       page; Windows PKZIP 2.50 uses Latin-1  (and  is  therefore
       incompatible  with  DOS PKZIP); Info-ZIP uses the OEM code
       page on DOS, OS/2 and Win3.x ports but Latin-1  everywhere

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UNZIP(1L)                                               UNZIP(1L)

       else; and Nico Mak's WinZip 6.x does not allow 8-bit pass-
       words at all.  UnZip 5.3 attempts to use the default char-
       acter set first (e.g., Latin-1), followed by the alternate
       one (e.g., OEM code page) to test  passwords.   On  EBCDIC
       systems,  if  both  of these fail, EBCDIC encoding will be
       tested as a  last  resort.   (Since  there  are  no  known
       archivers  that  encrypt  using EBCDIC encoding, EBCDIC is
       not tested on non-EBCDIC systems.)  ISO  character  encod-
       ings other than Latin-1 are not supported.

EXAMPLES
       To  use  unzip  to extract all members of the archive let-
       ters.zip into the  current  directory  and  subdirectories
       below it, creating any subdirectories as necessary:

           unzip letters

       To  extract  all  members  of letters.zip into the current
       directory only:

           unzip -j letters

       To test letters.zip, printing only a summary message indi-
       cating whether the archive is OK or not:

           unzip -tq letters

       To  test  all  zipfiles in the current directory, printing
       only the summaries:

           unzip -tq \*.zip

       (The backslash before the asterisk is only required if the
       shell  expands  wildcards, as in Unix; double quotes could
       have  been  used  instead,  as  in  the  source   examples
       below.)  To extract to standard output all members of let-