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), cre-
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 specifica-
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 other-
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 pro-
cessed, separated by spaces. (VMS versions com-
piled with VMSCLI defined must delimit files with
commas instead. See -v in OPTIONS below.) Regular
expressions (wildcards) may be used to match multi-
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 recre-
ated in the current directory; the -d option allows
extraction in an arbitrary directory (always assum-
ing one has permission to write to the directory).
This option need not appear at the end of the com-
mand line; it is also accepted before the zipfile
specification (with the normal options), immedi-
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 partic-
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 com-
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 conver-
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 differ-
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 auto-
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 indi-
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 [Unix only] set the timestamp on the archive(s) to
that of the newest file in each one. This corre-
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 informa-
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 operat-
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 vari-
ables 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 zip-
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
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, regard-
less of the supposed file type.
-b [non-VMS] treat all files as binary (no text con-
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 loca-
tions.
-C match filenames case-insensitively. unzip's phi-
losophy is ``you get what you ask for'' (this is
also responsible for the -L/-U change; see the rel-
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 plat-
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 cor-
respond to the behavior of many other operat-
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 ``make-
file'' (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 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
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
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
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
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
anyway, 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 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-
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 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:
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 envi-
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 any-
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 imme-
diately.
4 unzip was unable to allocate memory for one
or more buffers during program initializa-
tion.
5 unzip was unable to allocate memory or
unable to obtain a tty to read the decryp-
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 com-
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 con-
trol-C (or similar)
81 no files were found due to unsupported com-
pression methods or unsupported decryption.
(If even one additional file is successfully
processed, however, the exit status is 1.)
82 no files were found due to bad decryption
password(s). This is also the exit status
if no files were found due to a combination
of unsupported compression and bad pass-
words. As in the previous case, however, a
single successful file will result in an
exit status of 1 instead.)
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 con-
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 con-
trol-Break) can still be used to terminate unzip.
Under DEC Ultrix, unzip would sometimes fail on long zip-
files (bad CRC, not always reproducible). This was appar-
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 zip-
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 fresh-
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 renam-
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.
SEE ALSO
funzip(1L) zip(1L) zipcloak(1L) zipgrep(1L) zip-
info(1L) zipnote(1L) zipsplit(1L)
URL
The Info-ZIP home page is currently at
http://www.cdrom.com/pub/infozip/ .
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); Karl Davis
and 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 Robert
Heath (Windows GUI). 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 CONTRIBS 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)