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UNZIP(1L) UNZIP(1L)
NAME
unzip - list, test and extract compressed files in a ZIP archive
SYNOPSIS
unzip [-Z] [-cflptTuvz[abjnoqsCDKLMUVWX$/:^]] 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 sys-
tems. 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 pro-
gram, zip(1L), 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 those supported in commonly used Unix shells (sh, ksh, csh) 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 exclama-
tion 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). To specify a
verbatim left bracket, the three-character sequence ``[[]'' has to be used.
(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 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 normally match (`/') directory separators (for exceptions see the option
-W), 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 subdi-
rectories 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 particular,
``-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 command 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 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 overwrit-
ing, 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 auto-
matically). The reasons for this are somewhat subtle but have to do with the dif-
ferences 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 modifi-
cation 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 con-
versions).
-t test archive files. This option extracts each specified file in memory and com-
pares 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 prop-
erly.
-v list archive files (verbose format) or show 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. In contrast to most of the competing util-
ities, unzip removes the 12 additional header bytes of encrypted entries from the
compressed size numbers. Therefore, compressed size and compression ratio figures
are independent of the entry's encryption status and show the correct compression
performance. (The complete size of the encrypted compressed data stream for zip-
file entries is reported by the more verbose zipinfo(1L) reports, see the separate
manual.) 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 compilation 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 conjunction 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 charac-
ter 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 con-
trol-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. On VMS, see also -S.
-b [general] treat all files as binary (no text conversions). This is a shortcut for
---a.
-b [Tandem] force the creation files with filecode type 180 ('C') when extracting Zip
entries marked as "text". (On Tandem, -a is enabled by default, see above).
-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.
When extracting to standard output (-c or -p option in effect), the default conver-
sion of text record delimiters is disabled for binary (-b) resp. all (-bb) files.
-B [when compiled with UNIXBACKUP defined] save a backup copy of each overwritten
file. The backup file is gets the name of the target file with a tilde and option-
ally a unique sequence number (up to 5 digits) appended. The sequence number is
applied whenever another file with the original name plus tilde already exists.
When used together with the "overwrite all" option -o, numbered backup files are
never created. In this case, all backup files are named as the original file with
an appended tilde, existing backup files are deleted without notice. This feature
works similarly to the default behavior of emacs(1) in many locations.
Example: the old copy of ``foo'' is renamed to ``foo~''.
Warning: Users should be aware that the -B option does not prevent loss of existing
data under all circumstances. For example, when unzip is run in overwrite-all
mode, an existing ``foo~'' file is deleted before unzip attempts to rename ``foo''
to ``foo~''. When this rename attempt fails (because of a file locks, insufficient
privileges, or ...), the extraction of ``foo~'' gets cancelled, but the old backup
file is already lost. A similar scenario takes place when the sequence number
range for numbered backup files gets exhausted (99999, or 65535 for 16-bit sys-
tems). In this case, the backup file with the maximum sequence number is deleted
and replaced by the new backup version without notice.
-C use case-insensitive matching for the selection of archive entries from the com-
mand-line list of extract selection patterns. 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 com-
mand line will only match ``makefile'' in the archive, not ``Makefile'' or ``MAKE-
FILE'' (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 file specs in both the normal file list and the excluded-file list (xlist).
Please note that the -C option does neither affect the search for the zipfile(s)
nor the matching of archive entries to existing files on the extraction path. On a
case-sensitive file system, unzip will never try to overwrite a file ``FOO'' when
extracting an entry ``foo''!
-D skip restoration of timestamps for extracted items. Normally, unzip tries to
restore all meta-information for extracted items that are supplied in the Zip ar-
chive (and do not require privileges or impose a security risk). By specifying -D,
unzip is told to suppress restoration of timestamps for directories explicitly cre-
ated from Zip archive entries. This option only applies to ports that support set-
ting timestamps for directories (currently ATheOS, BeOS, MacOS, OS/2, Unix, VMS,
Win32, for other unzip ports, -D has no effect). The duplicated option -DD forces
suppression of timestamp restoration for all extracted entries (files and directo-
ries). This option results in setting the timestamps for all extracted entries to
the current time.
On VMS, the default setting for this option is -D for consistency with the behav-
iour of BACKUP: file timestamps are restored, timestamps of extracted directories
are left at the current time. To enable restoration of directory timestamps, the
negated option --D should be specified. On VMS, the option -D disables timestamp
restoration for all extracted Zip archive items. (Here, a single -D on the command
line combines with the default -D to do what an explicit -DD does on other sys-
tems.)
-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 [non-Acorn systems supporting long filenames with embedded commas, and only if com-
piled with ACORN_FTYPE_NFS defined] translate filetype information 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 com-
patible 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 Macintosh specific info is skipped.
Data-fork and resource-fork are restored as separate files.
-K [AtheOS, BeOS, Unix only] retain SUID/SGID/Tacky file attributes. Without this
flag, these attribute bits are cleared for security reasons.
-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 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 lower-
case. The -LL option forces conversion of every filename to lowercase, regardless
of the originating file system.
-M pipe all output through an internal pager similar to the Unix more(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, effec-
tively 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, over-
write all files, skip extraction of the current file, skip extraction of all exist-
ing 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 operating systems provide ways for any user to see the current com-
mand 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 zip-
file comments that may be stored in the archive, and possibly a summary when fin-
ished 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 oper-
ating 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 spa-
ces to underscores can eliminate the awkwardness in some cases.
-S [VMS] convert text files (-a, -aa) into Stream_LF record format, instead of the
text-file default, variable-length record format. (Stream_LF is the default record
format of VMS unzip. It is applied unless conversion (-a, -aa and/or -b, -bb) is
requested or a VMS-specific entry is processed.)
-U [UNICODE_SUPPORT only] modify or disable UTF-8 handling. When UNICODE_SUPPORT is
available, the option -U forces unzip to escape all non-ASCII characters from UTF-8
coded filenames as ``#Uxxxx'' (for UCS-2 characters, or ``#Lxxxxxx'' for unicode
codepoints needing 3 octets). This option is mainly provided for debugging purpose
when the fairly new UTF-8 support is suspected to mangle up extracted filenames.
The option -UU allows to entirely disable the recognition of UTF-8 encoded file-
names. The handling of filename codings within unzip falls back to the behaviour
of previous versions.
[old, obsolete usage] 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 particularly short lengths, the version numbers may be truncated or stripped
regardless of this option.)
-W [only when WILD_STOP_AT_DIR compile-time option enabled] modifies the pattern
matching routine so that both `?' (single-char wildcard) and `*' (multi-char wild-
card) do not match the directory separator character `/'. (The two-character
sequence ``**'' acts as a multi-char wildcard that includes the directory separator
in its matched characters.) Examples:
"*.c" matches "foo.c" but not "mydir/foo.c"
"**.c" matches both "foo.c" and "mydir/foo.c"
"*/*.c" matches "bar/foo.c" but not "baz/bar/foo.c"
"??*/*" matches "ab/foo" and "abc/foo"
but not "a/foo" or "a/b/foo"
This modified behaviour is equivalent to the pattern matching style used by the
shells of some of UnZip's supported target OSs (one example is Acorn RISC OS).
This option may not be available on systems where the Zip archive's internal direc-
tory separator character `/' is allowed as regular character in native operating
system filenames. (Currently, UnZip uses the same pattern matching rules for both
wildcard zipfile specifications and zip entry selection patterns in most ports.
For systems allowing `/' as regular filename character, the -W option would not
work as expected on a wildcard zipfile specification.)
-X [VMS, Unix, OS/2, NT, Tandem] restore owner/protection info (UICs and ACL entries)
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 extrac-
tion; 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.]
-Y [VMS] treat archived file name endings of ``.nnn'' (where ``nnn'' is a decimal
number) as if they were VMS version numbers (``;nnn''). (The default is to treat
them as file types.) Example:
"a.b.3" -> "a.b;3".
-$ [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 labeled as well. By default, volume labels are ignored.
-/ extensions
[Acorn only] overrides the extension list supplied by Unzip$Ext environment vari-
able. During extraction, filename extensions that match one of the items in this
extension list are swapped in front of the base name of the extracted file.
-: [all but Acorn, VM/CMS, MVS, Tandem] allows to extract archive members into loca-
tions outside of the current `` extraction root folder''. For security reasons,
unzip normally removes ``parent dir'' path components (``../'') from the names of
extracted file. This safety feature (new for version 5.50) prevents unzip from
accidentally writing files to ``sensitive'' areas outside the active extraction
folder tree head. The -: option lets unzip switch back to its previous, more lib-
eral behaviour, to allow exact extraction of (older) archives that used ``../''
components to create multiple directory trees at the level of the current extrac-
tion folder. This option does not enable writing explicitly to the root directory
(``/''). To achieve this, it is necessary to set the extraction target folder to
root (e.g. -d / ). However, when the -: option is specified, it is still possible
to implicitly write to the root directory by specifying enough ``../'' path compo-
nents within the zip archive. Use this option with extreme caution.
-^ [Unix only] allow control characters in names of extracted ZIP archive entries. On
Unix, a file name may contain any (8-bit) character code with the two exception '/'
(directory delimiter) and NUL (0x00, the C string termination indicator), unless
the specific file system has more restrictive conventions. Generally, this allows
to embed ASCII control characters (or even sophisticated control sequences) in file
names, at least on 'native' Unix file systems. However, it may be highly suspi-
cious to make use of this Unix "feature". Embedded control characters in file
names might have nasty side effects when displayed on screen by some listing code
without sufficient filtering. And, for ordinary users, it may be difficult to han-
dle such file names (e.g. when trying to specify it for open, copy, move, or delete
operations). Therefore, unzip applies a filter by default that removes potentially
dangerous control characters from the extracted file names. The -^ option allows to
override this filter in the rare case that embedded filename control characters are
to be intentionally restored.
-2 [VMS] force unconditionally conversion of file names to ODS2-compatible names. The
default is to exploit the destination file system, preserving case and extended
file name characters on an ODS5 destination file system; and applying the ODS2-com-
patibility file name filtering on an ODS2 destination file system.
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 file-
names from uppercase systems to lowercase, make it match names case-insensitively, make it
quieter, or make it always overwrite 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 commands:
Unix Bourne shell:
UNZIP=-qq; export UNZIP
Unix C shell:
setenv UNZIP -qq
OS/2 or MS-DOS:
set UNZIP=-qq
VMS (quotes for lowercase):
define UNZIP_OPTS "-qq"
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 over-
ride 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 confusing, but it is reasonably intu-
itive: 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 compati-
bility 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 zip-
file name) can be used to check the values of all four possible unzip and zipinfo environ-
ment 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 description of -f above for details. This vari-
able may also be necessary to get timestamps of extracted files to be set correctly. The
WIN32 (Win9x/ME/NT4/2K/XP/2K3) port of unzip gets the timezone configuration from the reg-
istry, assuming it is correctly set in the Control Panel. The TZ variable is ignored for
this port.
DECRYPTION
Encrypted archives are fully supported by Info-ZIP software, but due to United States
export restrictions, de-/encryption support might be disabled in your compiled binary.
However, since spring 2000, US export restrictions have been liberated, and our source ar-
chives do now include full crypt code. In case you need binary distributions with crypt
support enabled, see the file ``WHERE'' in any Info-ZIP source or binary distribution for
locations both inside and outside the US.
Some compiled versions of unzip may not 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 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 incorrect 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
extraction 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 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 ISO coding (Latin-1 etc.) everywhere else; and Nico
Mak's WinZip 6.x does not allow 8-bit passwords at all. UnZip 5.3 (or newer) attempts to
use the default character set first (e.g., Latin-1), followed by the alternate one (e.g.,
OEM code page) to test passwords. On EBCDIC systems, if both of these fail, EBCDIC encod-
ing will be tested as a last resort. (EBCDIC is not tested on non-EBCDIC systems, because
there are no known archivers that encrypt using EBCDIC encoding.) ISO character encodings
other than Latin-1 are not supported. The new addition of (partially) Unicode (resp.
UTF-8) support in UnZip 6.0 has not yet been adapted to the encryption password handling
in unzip. On systems that use UTF-8 as native character encoding, unzip simply tries
decryption with the native UTF-8 encoded password; the built-in attempts to check the
password in translated encoding have not yet been adapted for UTF-8 support and will con-
sequently fail.
EXAMPLES
To use unzip to extract all members of the archive letters.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 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-con-
verting 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 pro-
gram:
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 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 envi-
ronment 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 in options 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 zip-
file.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 suc-
cessfully 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 com-
pression 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'' (for zip 2.x) or ``zip -FF''
(for zip 3.x) must be performed on the concatenated archive in order to ``fix'' it. Also,
zip 3.0 and later can combine multi-part (split) archives into a combined single-file ar-
chive using ``zip -s- inarchive -O outarchive''. See the zip 3 manual page for more
information.) 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 charac-
ters) may not be portable across systems and/or other archivers. See the discussion in
DECRYPTION above.
unzip's -M (``more'') option tries to take into account automatic wrapping of long lines.
However, the code may fail to detect the correct wrapping locations. First, TAB characters
(and similar control sequences) are not taken into account, they are handled as ordinary
printable characters. Second, depending on the actual system / OS port, unzip may not
detect the true screen geometry but rather rely on "commonly used" default dimensions.
The correct handling of tabs would require the implementation of a query for the actual
tabulator setup on the output console.
Dates, times and permissions of stored directories are not restored except under Unix. (On
Windows NT and successors, timestamps are now restored.)
[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 ver-
sions 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 repro-
ducible). 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, directories and symbolic (soft) links.
[OS/2] Extended attributes for existing directories are only updated if the -o (``over-
write 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
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
funzip(1L), zip(1L), zipcloak(1L), zipgrep(1L), zipinfo(1L), zipnote(1L), zipsplit(1L)
URL
The Info-ZIP home page is currently at
http://www.info-zip.org/pub/infozip/
or
ftp://ftp.info-zip.org/pub/infozip/ .
AUTHORS
The primary Info-ZIP authors (current semi-active members of the Zip-Bugs workgroup) are:
Ed Gordon (Zip, general maintenance, shared code, Zip64, Win32, Unix, Unicode); Christian
Spieler (UnZip maintenance coordination, VMS, MS-DOS, Win32, shared code, general Zip and
UnZip integration and optimization); Onno van der Linden (Zip); Mike White (Win32, Windows
GUI, Windows DLLs); Kai Uwe Rommel (OS/2, Win32); Steven M. Schweda (VMS, Unix, support of
new features); Paul Kienitz (Amiga, Win32, Unicode); 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, Info-ZIP Site maintenance); Steve Salis-
bury (Win32); Steve Miller (Windows CE GUI), Johnny Lee (MS-DOS, Win32, Zip64); and Dave
Smith (Tandem NSK).
The following people were former members of the Info-ZIP development group and provided
major contributions to key parts of the current code: Greg ``Cave Newt'' Roelofs (UnZip,
unshrink decompression); Jean-loup Gailly (deflate compression); Mark Adler (inflate
decompression, fUnZip).
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)
v5.32 3 Nov 97 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.4 28 Nov 98 Info-ZIP (Zip-Bugs subgroup, SPC)
v5.41 16 Apr 00 Info-ZIP (Zip-Bugs subgroup, SPC)
v5.42 14 Jan 01 Info-ZIP (Zip-Bugs subgroup, SPC)
v5.5 17 Feb 02 Info-ZIP (Zip-Bugs subgroup, SPC)
v5.51 22 May 04 Info-ZIP (Zip-Bugs subgroup, SPC)
v5.52 28 Feb 05 Info-ZIP (Zip-Bugs subgroup, SPC)
v6.0 20 Apr 09 Info-ZIP (Zip-Bugs subgroup, SPC)
Info-ZIP 20 April 2009 (v6.0) UNZIP(1L)
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