unzip.txt

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       -:     [all but Acorn,  VM/CMS,  MVS,  Tandem]  allows  to
              extract  archive  members into locations outside of
              the current `` extraction root folder''. For  secu-
              rity reasons, unzip normally removes ``parent dir''
              path  components  (``../'')  from  the   names   of
              extracted  file.  This safety feature (new for ver-
              sion 5.50) prevents unzip from accidentally writing
              files  to  ``sensitive''  areas  outside the active
              extraction folder tree head.  The  -:  option  lets
              unzip  switch  back  to  its previous, more liberal
              behaviour, to allow  exact  extraction  of  (older)
              archives  that  used  ``../''  components to create
              multiple directory trees at the level of  the  cur-
              rent  extraction  folder.   This  option  does  not
              enable writing explicitly  to  the  root  directory
              (``/'').   To  achieve this, it is necessary to set
              the extraction target folder to root (e.g. -d /  ).
              However,  when  the  -:  option is specified, it is
              still possible to  implicitly  write  to  the  root
              directory by specifiying enough ``../'' path compo-
              nents within the zip archive.  Use this option with
              extreme caution.

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

         Unix Bourne shell:
              UNZIP=-qq; export UNZIP

         Unix C shell:
              setenv UNZIP -qq

         OS/2 or MS-DOS:
              set UNZIP=-qq

         VMS (quotes for lowercase):
              define UNZIP_OPTS ""-qq""

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UNZIP(1L)                                               UNZIP(1L)

       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 to get timestamps of
       extracted  files  to  be   set   correctly.    The   WIN32
       (Win9x/ME/NT4/2K/XP/2K3)  port  of unzip gets the timezone
       configuration from the registry, assuming it is  correctly
       set  in the Control Panel.  The TZ variable is ignored for
       this port.

DECRYPTION
       Encrypted archives are fully supported by  Info-ZIP  soft-
       ware,  but  due  to  United  States  export  restrictions,
       de-/encryption support might be disabled in your  compiled
       binary.   However,  since  spring 2000, US export restric-
       tions have been liberated, and our source archives do  now
       include  full crypt code.  In case you need binary distri-
       butions with crypt support enabled, see the file ``WHERE''
       in  any  Info-ZIP  source or binary distribution for loca-
       tions both inside and outside the US.

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UNZIP(1L)                                               UNZIP(1L)

       Some compiled versions of unzip may  not  support  decryp-
       tion.   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
       else; and Nico Mak's WinZip 6.x does not allow 8-bit pass-
       words at all.  UnZip 5.3 (or newer) attempts  to  use  the
       default  character  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.  (EBCDIC is not tested on
       non-EBCDIC  systems,  because there are no known archivers

Info-ZIP             28 February 2005 (v5.52)                  12

UNZIP(1L)                                               UNZIP(1L)

       that encrypt using EBCDIC encoding.)  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-
       ters.zip whose names end in .tex, auto-converting  to  the
       local  end-of-line  convention  and piping the output into
       more(1):

           unzip -ca letters \*.tex | more

       To extract the binary file paper1.dvi to  standard  output
       and pipe it to a printing program:

           unzip -p articles paper1.dvi | dvips

       To  extract all FORTRAN and C source files--*.f, *.c, *.h,
       and Makefile--into the /tmp directory:

           unzip source.zip "*.[fch]" Makefile -d /tmp

       (the double quotes are necessary only in Unix and only  if
       globbing  is  turned  on).   To  extract all FORTRAN and C
       source files, regardless of case (e.g., both *.c and  *.C,
       and any makefile, Makefile, MAKEFILE or similar):

           unzip -C source.zip "*.[fch]" makefile -d /tmp

       To extract any such files but convert any uppercase MS-DOS
       or VMS names to lowercase and convert the line-endings  of

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UNZIP(1L)                                               UNZIP(1L)

       all of the files to the local standard (without respect to
       any files that might be marked ``binary''):

           unzip -aaCL source.zip "*.[fch]" makefile -d /tmp

       To extract only newer versions of the files already in the
       current  directory, without querying (NOTE:  be careful of
       unzipping  in  one   timezone   a   zipfile   created   in
       another--ZIP  archives other than those created by Zip 2.1
       or later contain no timezone information, and a  ``newer''
       file from an eastern timezone may, in fact, be older):

           unzip -fo sources

       To extract newer versions of the files already in the cur-
       rent directory and to create any files not  already  there
       (same caveat as previous example):

           unzip -uo sources

       To  display  a  diagnostic  screen showing which unzip and
       zipinfo  options  are  stored  in  environment  variables,
       whether  decryption  support was compiled in, the compiler
       with which unzip was compiled, etc.:

           unzip -v

       In the last five examples, assume that UNZIP or UNZIP_OPTS
       is set to -q.  To do a singly quiet listing:

           unzip -l file.zip

       To do a doubly quiet listing:

           unzip -ql file.zip

       (Note  that  the ``.zip'' is generally not necessary.)  To
       do a standard listing: