UNZIP(1) General Commands Manual UNZIP(1)
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. The default behavior (with no options) is to extract into the current direc-
tory (and subdirectories below it) all files from the specified ZIP archive. A companion program, zip (available from
http://www.cdrom.com/pub/infozip/), creates 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 specification 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 end-
ing 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 otherwise 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 processed, separated by spaces. (VMS versions compiled with VMSCLI defined must delimit
files with commas instead. See -v in OPTIONS below.) Regular expressions (wildcards) may be used to match multiple 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 recreated in the current directory;
the -d option allows extraction in an arbitrary directory (always assuming one has permission to write to the directory). This
option need not appear at the end of the command line; it is also accepted before the zipfile specification (with the normal
options), immediately 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 particu-
lar, ``-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(1) mode. If the first option on the command line is -Z, the remaining options are taken to be zipinfo(1) 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 conversion 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 vari-
able is usually set automatically). The reasons for this are somewhat subtle but have to do with the differences 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 automatic 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
individual 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 corresponds 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 information 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 operating system
for which it was compiled, as well as (possibly) the hardware on which it was compiled, the compiler and version used, and the com-
pilation date; any special compilation options that might affect the program's operation (see also DECRYPTION below); and any
options stored in environment variables that might do the same (see ENVIRONMENT OPTIONS below). As a modifier it works in conjunc-
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 zipinfo 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 perfect; 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, regardless of the supposed file type.
-b [non-VMS] treat all files as binary (no text conversions). 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 locations.
-C match filenames case-insensitively. unzip's philosophy is ``you get what you ask for'' (this is also responsible for the -L/-U
change; see the relevant 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 platforms, 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 correspond to the
behavior of many other operating/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
``makefile'' (or ``make*'', or similar). The -C option affects files in both the normal file list and the excluded-file list
(xlist).
-j junk paths. The archive's directory structure is not recreated; all files are deposited in the extraction directory (by default,
the current one).
-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 identical to the old behavior with the -U option, which is now obso-
lete 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 ter-
minated 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 available 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, or with the -N option of the
Amiga port of zip, 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 operating 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 possi-
ble, 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 support 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 numbers are stripped, but this option allows them to be retained. (On file systems that limit filenames to particu-
larly 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 portabil-
ity 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 proba-
bly 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 overwrite or never over-
write 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 commands:
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 over-
ride 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 confusing, 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 confused with the environment variable), and UNZIP for all other operating systems. For compatibility with zip,
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 correctly. See the descrip-
tion of -f above for details. This variable may also be necessary in order for timestamps on extracted files to be set correctly. Under
Windows 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 software, 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 http://www.cdrom.com/pub/infozip/doc/WHERE or the WHERE file in any Info-ZIP source
or binary distribution 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 normally; 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 fea-
ture 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 incorrect password is given but it passes the header test anyway, either an incorrect CRC will be gener-
ated for the extracted data or else unzip will fail during the extraction because the ``decrypted'' bytes do not constitute a valid com-
pressed 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 fur-
ther prompting. Only unencrypted files in the archive(s) will thereafter be extracted. (In fact, that's not quite true; older versions of
zip and zipcloak allowed null passwords, so unzip checks each encrypted file to see if the null password works. This may result in ``false
positives'' 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 passwords at all. UnZip 5.3 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. (Since there
are no known archivers that encrypt using EBCDIC encoding, EBCDIC is not tested on non-EBCDIC systems.) ISO character encodings other than
Latin-1 are not supported.
EXAMPLES
To use unzip to extract all members of the archive letters.zip into the current directory and subdirectories below it, creating any subdi-
rectories 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 indicating 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 letters.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 time-
zone 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 current 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 environment 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 anyway. 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 immediately.
4 unzip was unable to allocate memory for one or more buffers during program initialization.
5 unzip was unable to allocate memory or unable to obtain a tty to read the decryption 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 command 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 control-C (or similar)
81 testing or extraction of one or more files failed due to unsupported compression methods or unsupported decryption.
82 no files were found due to bad decryption password(s). (If even one file is successfully 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*nor-
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 conjunction 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 occur-
rence 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 control-Break) can still be used to terminate unzip.
Under DEC Ultrix, unzip would sometimes fail on long zipfiles (bad CRC, not always reproducible). This was apparently 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 zipfile, nor are hard-linked files relinked. Basically the only file types restored by unzip are regular files, direc-
tories 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 ar-
chive normally (with or without freshening/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 renaming; 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.
SEE ALSO
zipinfo(1)
URL
The Info-ZIP home page is currently at http://www.cdrom.com/pub/infozip/ .
COPYRIGHT
Distributed with permission from Info-ZIP. Please see http://www.cdrom.com/pub/infozip/doc/COPYING for copyright information.
AUTHORS
The primary Info-ZIP authors (current semi-active members of the Zip-Bugs workgroup) are: Greg ``Cave Newt'' Roelofs (UnZip); Onno van der
Linden (Zip); Jean-loup Gailly (compression); Mark Adler (decompression, fUnZip); Christian Spieler (VMS, MS-DOS, Windows 95, NT, shared
code, general Zip and UnZip integration and optimization); Mike White (Windows GUI, Windows DLLs); Kai Uwe Rommel (OS/2); Paul Kienitz
(Amiga, Windows 95); Chris Herborth (BeOS, QNX, Atari); Jonathan Hudson (SMS/QDOS); Sergio Monesi (Acorn RISC OS); Harald Denker (Atari,
MVS); John Bush (Solaris, Amiga); Hunter Goatley (VMS); Steve Salisbury (Windows 95, NT); Steve Miller (Windows CE GUI), Johnny Lee (MS-
DOS, Windows 95, NT); and Dave Smith (Tandem NSK). The author of the original unzip code upon which Info-ZIP's was based is Samuel H.
Smith; Carl Mascott did the first Unix port; and David P. Kirschbaum organized and led Info-ZIP in its early days with Keith Petersen
hosting the original mailing list at WSMR-SimTel20. The full list of contributors to UnZip has grown quite large; please refer to the CON-
TRIBS file in the UnZip source distribution for a relatively complete version.
VERSIONS
v1.2 15 Mar 89 Samuel H. Smith
v2.0 9 Sep 89 Samuel H. Smith
v2.x fall 1989 many Usenet contributors
v3.0 1 May 90 Info-ZIP (DPK, consolidator)
v3.1 15 Aug 90 Info-ZIP (DPK, consolidator)
v4.0 1 Dec 90 Info-ZIP (GRR, maintainer)
v4.1 12 May 91 Info-ZIP
v4.2 20 Mar 92 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.0 21 Aug 92 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.01 15 Jan 93 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.1 7 Feb 94 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.11 2 Aug 94 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.12 28 Aug 94 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.2 30 Apr 96 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.3 22 Apr 97 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.31 31 May 97 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.32 3 Nov 97 Info-ZIP (Zip-Bugs subgroup, GRR)
Info-ZIP 3 November 1997 (v5.32) UNZIP(1)