Newsgroup: it.comp.www.php
Titolo: Compressione file

E' possibile comprimere un file spedito sul server tramite upload in formato
zip?
C'è bisogno di qualche particolare libreria?
Saluti
M.

 ha scritto nel messaggio
news:a28n33$v6hvg$1...@ID-97960.news.dfncis.de...

1)Si puo
2)Si, serve una libreria
3) vedi qui 
http://www.gzip.org/zlib/
 e
http://www.php.net/manual/it/ref.zlib.php
Se ci riesci posta sul newgroup il codice penso interessi a molti
buon lavoro.

 
http://www.php.net/manual/it/ref.zlib.php
Oppure se il server ha installato "unzip"
exec("unzip -o nomefile");
-o č una delle tante impostazioni: sperando di fare cosa gradita copio la
spiegazione del manuale di UNZIP
LAMASE
_____________________________________________
UNZIP(1L)                                               UNZIP(1L)
NAME
       unzip  -  list, test and extract compressed files in a ZIP
       archive
SYNOPSIS
       unzip    [-Z]    [-cflptuvz[abjnoqsCLMVX$]]     file[.zip]
       [file(s) ...]  [-x xfile(s) ...] [-d exdir]
DESCRIPTION
       unzip  will  list,  test,  or  extract  files  from  a ZIP
       archive, commonly found on MS-DOS  systems.   The  default
       behavior  (with no options) is to extract into the current
       directory (and subdirectories below it) all files from the
       specified ZIP archive.  A companion program, zip(1L), creĄ
       ates ZIP  archives;  both  programs  are  compatible  with
       archives created by PKWARE's PKZIP and PKUNZIP for MS-DOS,
       but in many cases the program options or default behaviors
       differ.
ARGUMENTS
       file[.zip]
              Path of the ZIP archive(s).  If the file specificaĄ
              tion is a wildcard, each matching file is processed
              in  an order determined by the operating system (or
              file system).  Only the filename can be a wildcard;
              the  path  itself cannot.  Wildcard expressions are
              similar to Unix egrep(1) (regular) expressions  and
              may contain:
              *      matches a sequence of 0 or more characters
              ?      matches exactly 1 character
              [...]  matches  any  single  character found inside
                     the brackets;  ranges  are  specified  by  a
                     beginning character, a hyphen, and an ending
                     character.  If an  exclamation  point  or  a
                     caret (`!' or `^') follows the left bracket,
                     then the  range  of  characters  within  the
                     brackets  is complemented (that is, anything
                     except the characters inside the brackets is
                     considered a match).
              (Be  sure  to quote any character that might otherĄ
              wise be interpreted or modified  by  the  operating
              system,  particularly  under  Unix and VMS.)  If no
              matches are found, the specification is assumed  to
              be  a literal filename; and if that also fails, the
              suffix .zip is appended.  Note that self-extracting
              ZIP  files  are  supported,  as  with any other ZIP
              archive; just specify  the  .exe  suffix  (if  any)
              explicitly.
       [file(s)]
              An  optional  list  of  archive  members to be proĄ
              cessed, separated by spaces.   (VMS  versions  comĄ
              piled  with  VMSCLI defined must delimit files with
              commas instead.  See -v in OPTIONS below.)  Regular
              expressions (wildcards) may be used to match multiĄ
              ple members; see above.  Again, be  sure  to  quote
              expressions  that  would  otherwise  be expanded or
              modified by the operating system.
       [-x xfile(s)]
              An optional list of archive members to be  excluded
              from  processing.   Since wildcard characters match
              directory separators (`/'), this option may be used
              to  exclude  any  files that are in subdirectories.
              For example, ``unzip  foo  *.[ch]  -x  */*''  would
              extract  all  C source files in the main directory,
              but none in any  subdirectories.   Without  the  -x
              option,  all  C  source  files  in  all directories
              within the zipfile would be extracted.
       [-d exdir]
              An optional directory to which  to  extract  files.
              By default, all files and subdirectories are recreĄ
              ated in the current directory; the -d option allows
              extraction in an arbitrary directory (always assumĄ
              ing one has permission to write to the  directory).
              This  option need not appear at the end of the comĄ
              mand line; it is also accepted before  the  zipfile
              specification  (with  the  normal options), immediĄ
              ately after the zipfile specification,  or  between
              the  file(s)  and  the  -x  option.  The option and
              directory may be  concatenated  without  any  white
              space  between  them,  but note that this may cause
              normal shell behavior to be suppressed.  In particĄ
              ular, ``-d ~'' (tilde) is expanded by Unix C shells
              into the name of the  user's  home  directory,  but
              ``-d~''  is treated as a literal subdirectory ``~''
              of the current directory.
OPTIONS
       Note that,  in  order  to  support  obsolescent  hardware,
       unzip's  usage  screen  is  limited  to 22 or 23 lines and
       should therefore be considered  only  a  reminder  of  the
       basic  unzip  syntax rather than an exhaustive list of all
       possible flags.  The exhaustive list follows:
       -Z     zipinfo(1L) mode.  If the first option on the  comĄ
              mand line is -Z, the remaining options are taken to
              be zipinfo(1L) options.  See the appropriate manual
              page for a description of these options.
       -A     [OS/2,  Unix DLL] print extended help for the DLL's
              programming interface (API).
       -c     extract files  to  stdout/screen  (``CRT'').   This
              option  is similar to the -p option except that the
              name of each file is printed as  it  is  extracted,
              the  -a option is allowed, and ASCII-EBCDIC converĄ
              sion is  automatically  performed  if  appropriate.
              This  option  is  not  listed  in  the  unzip usage
              screen.
       -f     freshen existing files, i.e.,  extract  only  those
              files that already exist on disk and that are newer
              than the disk copies.   By  default  unzip  queries
              before  overwriting,  but the -o option may be used
              to suppress the  queries.   Note  that  under  many
              operating  systems,  the  TZ (timezone) environment
              variable must be set correctly in order for -f  and
              -u  to  work  properly  (under Unix the variable is
              usually set automatically).  The reasons  for  this
              are somewhat subtle but have to do with the differĄ
              ences between DOS-format file times  (always  local
              time) and Unix-format times (always in GMT/UTC) and
              the necessity to compare the  two.   A  typical  TZ
              value  is  ``PST8PDT''  (US Pacific time with autoĄ
              matic  adjustment  for  Daylight  Savings  Time  or
              ``summer time'').
       -l     list  archive  files  (short  format).   The names,
              uncompressed file sizes and modification dates  and
              times  of  the  specified  files are printed, along
              with totals for all files specified.  If UnZip  was
              compiled  with  OS2_EAS defined, the -l option also
              lists columns for the sizes of stored OS/2 extended
              attributes  (EAs)  and  OS/2  access  control lists
              (ACLs).  In addition, the zipfile comment and indiĄ
              vidual  file comments (if any) are displayed.  If a
              file was archived from a  single-case  file  system
              (for  example,  the old MS-DOS FAT file system) and
              the -L option was given, the filename is  converted
              to lowercase and is prefixed with a caret (^).
       -p     extract  files  to  pipe (stdout).  Nothing but the
              file data is sent to  stdout,  and  the  files  are
              always extracted in binary format, just as they are
              stored (no conversions).
       -t     test archive  files.   This  option  extracts  each
              specified  file  in  memory  and  compares  the CRC
              (cyclic redundancy check, an enhanced checksum)  of
              the  expanded  file with the original file's stored
              CRC value.
       -T     [most OSes] set the timestamp on the archive(s)  to
              that  of  the newest file in each one.  This correĄ
              sponds to zip's -go option except that  it  can  be
              used   on   wildcard  zipfiles  (e.g.,  ``unzip  -T
              \*.zip'') and is much faster.
       -u     update  existing  files  and  create  new  ones  if
              needed.   This option performs the same function as
              the -f option, extracting (with query)  files  that
              are  newer  than  those with the same name on disk,
              and in addition it extracts those files that do not
              already  exist  on disk.  See -f above for informaĄ
              tion on setting the timezone properly.
       -v     be verbose or print diagnostic version info.   This
              option  has  evolved  and  now  behaves  as both an
              option and a modifier.  As an  option  it  has  two
              purposes:   when  a  zipfile  is  specified with no
              other options, -v lists  archive  files  verbosely,
              adding to the basic -l info the compression method,
              compressed size, compression ratio and 32-bit  CRC.
              When no zipfile is specified (that is, the complete
              command  is  simply  ``unzip  -v''),  a  diagnostic
              screen  is  printed.   In  addition  to  the normal
              header with release date and version,  unzip  lists
              the home Info-ZIP ftp site and where to find a list
              of other ftp and non-ftp sites; the target  operatĄ
              ing  system  for  which it was compiled, as well as
              (possibly) the hardware on which it  was  compiled,
              the  compiler and version used, and the compilation
              date; any special compilation  options  that  might
              affect the program's operation (see also DECRYPTION
              below); and any options stored in environment variĄ
              ables  that  might  do  the  same  (see ENVIRONMENT
              OPTIONS below).  As a modifier it works in conjuncĄ
              tion  with other options (e.g., -t) to produce more
              verbose or debugging output; this is not yet  fully
              implemented but will be in future releases.
       -z     display only the archive comment.
MODIFIERS
       -a     convert  text  files.   Ordinarily  all  files  are
              extracted exactly as they are stored (as ``binary''
              files).   The  -a option causes files identified by
              zip as text files (those with the `t' label in zipĄ
              info listings, rather than `b') to be automatically
              extracted as such, converting line endings, end-of-
              file  characters  and  the  character set itself as
              necessary.  (For example, Unix files use line feeds
              (LFs) for end-of-line (EOL) and have no end-of-file
              (EOF)  marker;  Macintoshes  use  carriage  returns
              (CRs)  for  EOLs; and most PC operating systems use
              CR+LF for EOLs and control-Z for EOF.  In addition,
              IBM mainframes and the Michigan Terminal System use
              EBCDIC rather than the more common ASCII  character
              set,  and  NT  supports  Unicode.)  Note that zip's
              identification of text files is by  no  means  perĄ
              fect;  some  ``text''  files may actually be binary
              and vice versa.  unzip therefore prints  ``[text]''
              or  ``[binary]'' as a visual check for each file it
              extracts when using the -a option.  The -aa  option
              forces  all  files to be extracted as text, regardĄ
              less of the supposed file type.
       -b     [non-VMS] treat all files as binary (no  text  conĄ
              versions).  This is a shortcut for ---a.
       -b     [VMS]  auto-convert  binary files (see -a above) to
              fixed-length, 512-byte record format.  Doubling the
              option  (-bb)  forces  all files to be extracted in
              this format.
       -B     [Unix only, and only if  compiled  with  UNIXBACKUP
              defined]  save  a  backup  copy of each overwritten
              file with a tilde appended (e.g., the old  copy  of
              ``foo''  is  renamed to ``foo~'').  This is similar
              to the default behavior of emacs(1) in  many  locaĄ
              tions.
       -C     match  filenames  case-insensitively.  unzip's phiĄ
              losophy is ``you get what you ask  for''  (this  is
              also responsible for the -L/-U change; see the relĄ
              evant options below).  Because  some  file  systems
              are  fully  case-sensitive (notably those under the
              Unix  operating  system)  and  because   both   ZIP
              archives and unzip itself are portable across platĄ
              forms, unzip's default behavior is  to  match  both
              wildcard  and  literal  filenames case-sensitively.
              That is, specifying  ``makefile''  on  the  command
              line  will  only match ``makefile'' in the archive,
              not ``Makefile'' or ``MAKEFILE'' (and similarly for
              wildcard specifications).  Since this does not corĄ
              respond to  the  behavior  of  many  other  operatĄ
              ing/file  systems  (for  example,  OS/2 HPFS, which
              preserves mixed case but is not sensitive  to  it),
              the  -C  option  may  be used to force all filename
              matches to be  case-insensitive.   In  the  example
              above,  all  three  files  would then match ``makeĄ
              file'' (or ``make*'', or similar).  The  -C  option
              affects  files in both the normal file list and the
              excluded-file list (xlist).
       -E     [MacOS only] display contents of MacOS extra  field
              during restore operation.
       -F     [Acorn  only]  suppress  removal  of  NFS  filetype
              extension from stored filenames.
       -F     [Unix   only,   and   only   if    compiled    with
              ACORN_FTYPE_NFS  defined] translate filetype inforĄ
              mation from ACORN RISC OS extra field blocks into a
              NFS  filetype  extension and append it to the names
              of the extracted files.  (When the stored  filename
              appears  to  already  have an appended NFS filetype
              extension, it is replaced  by  the  info  from  the
              extra field.)
       -i     [MacOS only] ignore filenames stored in MacOS extra
              fields.  Instead,  the  most  compatible   filename
              stored in the generic part of the entry's header is
              used.
       -j     junk paths.  The archive's directory  structure  is
              not  recreated;  all  files  are  deposited  in the
              extraction directory (by default, the current one).
       -J     [BeOS  only] junk file attributes.  The file's BeOS
              file attributes are not restored, just  the  file's
              data.
       -J     [MacOS only] ignore MacOS extra fields.  All MacinĄ
              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  identiĄ
              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
              being viewed.  On some systems the number of availĄ
              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 operĄ
              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 supĄ
              port spaces in filenames.  Conversion of spaces  to
              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  numĄ
              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 overĄ
       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  comĄ
       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  conĄ
       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 conĄ
       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 corĄ
       rectly.  See the description  of  -f  above  for  details.
       This  variable  may  also be necessary in order for timesĄ
       tamps on extracted files to be set correctly.  Under  WinĄ
       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 softĄ
       ware, but due to United States  export  restrictions,  the
       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 distribuĄ
       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 norĄ
       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 incorĄ
       rect password is given but it passes the header test  anyĄ
       way,  either  an  incorrect  CRC will be generated for the
       extracted data or else unzip will fail during the  extracĄ
       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 posiĄ
       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 passĄ
       words at all.  UnZip 5.3 attempts to use the default charĄ
       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  encodĄ
       ings other than Latin-1 are not supported.
EXAMPLES
       To  use  unzip  to extract all members of the archive letĄ
       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 indiĄ
       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 letĄ
       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
       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 curĄ
       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:
           unzip --ql file.zip
       or
           unzip -l-q file.zip
       or
           unzip -l--q file.zip       (extra minuses don't hurt)
TIPS
       The current maintainer, being a lazy sort, finds  it  very
       useful  to define a pair of aliases:  tt for ``unzip -tq''
       and ii for ``unzip -Z'' (or ``zipinfo'').   One  may  then
       simply  type  ``tt zipfile'' to test an archive, something
       that is worth making a habit of doing.   With  luck  unzip
       will  report  ``No  errors  detected in compressed data of
       zipfile.zip,'' after which  one  may  breathe  a  sigh  of
       relief.
       The maintainer also finds it useful to set the UNZIP enviĄ
       ronment variable to ``-aL'' and is tempted to  add  ``-C''
       as well.  His ZIPINFO variable is set to ``-z''.
DIAGNOSTICS
       The  exit  status  (or  error level) approximates the exit
       codes defined by PKWARE and takes on the following values,
       except under VMS:
              0      normal; no errors or warnings detected.
              1      one or more warning errors were encountered,
                     but processing completed  successfully  anyĄ
                     way.   This  includes  zipfiles where one or
                     more files was skipped  due  to  unsupported
                     compression  method  or  encryption  with an
                     unknown password.
              2      a generic error in the  zipfile  format  was
                     detected.   Processing  may  have  completed
                     successfully anyway;  some  broken  zipfiles
                     created by other archivers have simple work-
                     arounds.
              3      a severe error in  the  zipfile  format  was
                     detected.   Processing probably failed immeĄ
                     diately.
              4      unzip was unable to allocate memory for  one
                     or  more  buffers during program initializaĄ
                     tion.
              5      unzip  was  unable  to  allocate  memory  or
                     unable  to  obtain a tty to read the decrypĄ
                     tion password(s).
              6      unzip was unable to allocate  memory  during
                     decompression to disk.
              7      unzip  was  unable to allocate memory during
                     in-memory decompression.
              8      [currently not used]
              9      the specified zipfiles were not found.
              10     invalid options were specified on  the  comĄ
                     mand line.
              11     no matching files were found.
              50     the disk is (or was) full during extraction.
              51     the end of the ZIP archive  was  encountered
                     prematurely.
              80     the user aborted unzip prematurely with conĄ
                     trol-C (or similar)
              81     testing or extraction of one or  more  files
                     failed  due to unsupported compression methĄ
                     ods or unsupported decryption.
              82     no files were found due  to  bad  decryption
                     password(s).   (If even one file is successĄ
                     fully processed, however, the exit status is
                     1.)
       VMS  interprets  standard  Unix  (or  PC) return values as
       other, scarier-looking things, so unzip instead maps  them
       into  VMS-style  status  codes.  The current mapping is as
       follows:   1 (success) for  normal  exit,  0x7fff0001  for
       warning     errors,     and    (0x7fff000?    +    16*norĄ
       mal_unzip_exit_status) for all other errors, where the `?'
       is  2  (error)  for  unzip values 2, 9-11 and 80-82, and 4
       (fatal error) for the remaining ones (3-8,  50,  51).   In
       addition,  there  is  a  compilation option to expand upon
       this behavior:  defining RETURN_CODES results in a  human-
       readable explanation of what the error status means.
BUGS
       Multi-part  archives are not yet supported, except in conĄ
       junction  with  zip.   (All  parts  must  be  concatenated
       together  in  order, and then ``zip -F'' must be performed
       on the concatenated archive in order to ``fix'' it.)  This
       will definitely be corrected in the next major release.
       Archives  read  from standard input are not yet supported,
       except with funzip (and then only the first member of  the
       archive can be extracted).
       Archives  encrypted  with 8-bit passwords (e.g., passwords
       with accented European characters)  may  not  be  portable
       across systems and/or other archivers.  See the discussion
       in DECRYPTION above.
       unzip's -M (``more'') option is overly simplistic  in  its
       handling  of  screen  output;  as noted above, it fails to
       detect the wrapping of long lines and  may  thereby  cause
       lines  at  the top of the screen to be scrolled off before
       being read.  unzip should detect and treat each occurrence
       of   line-wrap  as  one  additional  line  printed.   This
       requires knowledge of the screen's width as  well  as  its
       height.   In addition, unzip should detect the true screen
       geometry on all systems.
       Dates, times and permissions of stored directories are not
       restored except under Unix.
       [MS-DOS]  When extracting or testing files from an archive
       on a defective floppy diskette, if the ``Fail'' option  is
       chosen  from  DOS's ``Abort, Retry, Fail?'' message, older
       versions of unzip may hang the system, requiring a reboot.
       This  problem  appears to be fixed, but control-C (or conĄ
       trol-Break) can still be used to terminate unzip.
       Under DEC Ultrix, unzip would sometimes fail on long  zipĄ
       files (bad CRC, not always reproducible).  This was apparĄ
       ently due either to a hardware bug (cache  memory)  or  an
       operating  system bug (improper handling of page faults?).
       Since Ultrix has been abandoned in favor of  Digital  Unix
       (OSF/1), this may not be an issue anymore.
       [Unix]  Unix  special  files  such  as FIFO buffers (named
       pipes),  block  devices  and  character  devices  are  not
       restored  even if they are somehow represented in the zipĄ
       file, nor are hard-linked files relinked.   Basically  the
       only  file  types  restored  by  unzip  are regular files,
       directories and symbolic (soft) links.
       [OS/2] Extended attributes for  existing  directories  are
       only  updated  if  the  -o  (``overwrite  all'') option is
       given.  This is a  limitation  of  the  operating  system;
       because  directories  only have a creation time associated
       with them, unzip has  no  way  to  determine  whether  the
       stored  attributes  are newer or older than those on disk.
       In practice this may mean a two-pass approach is required:
       first  unpack the archive normally (with or without freshĄ
       ening/updating existing files), then  overwrite  just  the
       directory entries (e.g., ``unzip -o foo */'').
       [VMS]  When  extracting  to  another  directory,  only the
       [.foo] syntax is accepted for the -d  option;  the  simple
       Unix foo syntax is silently ignored (as is the less common
       VMS foo.dir syntax).
       [VMS]  When  the  file  being  extracted  already  exists,
       unzip's  query only allows skipping, overwriting or renamĄ
       ing; there should additionally be a choice for creating  a
       new  version  of  the  file.   In  fact, the ``overwrite''
       choice does create a new version; the old version  is  not
       overwritten or deleted.
_____________________________________

 3) vedi qui 
http://www.gzip.org/zlib/
 e
Uhm... se non ho capito male la domanda, chiede se si puo` zippare un
file PRIMA che venga mandato tramite upload form verso il server.
Questo, a quanto mi risulta, non si puo` fare.
Si puo` fare il contrario con il sistema che dici tu, cioe` zippare un
file prima di farlo scaricare.
Bye.

 ha scritto nel messaggio
news:a29m6r$uooc5$1...@ID-94575.news.dfncis.de...

Si, no ehm ehm....
io spedisco tramite uno script upload un file sul server, dopo lo zippo e lo
archivio.
Ok?
Moana

archivio.
Allora, quando il server ha il file in mano, usa "zip" (Unix) o "PKZIP"
(Windows) via "exec".
Leonardo