unzip(1)
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 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(1), 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 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). 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 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 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 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 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(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 variable 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 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 utilities, 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 zipfile entries is reported by the more verbose zipinfo(1) 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 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. 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
conversion 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 optionally 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 systems). 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 command-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 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 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 archive (and do not require
privileges or impose a security risk). By specifying -D, unzip
is told to suppress restoration of timestamps for directories
explicitly created from Zip archive entries. This option only
applies to ports that support setting 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 directories). 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 behaviour 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 systems.)
-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 compiled 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 compatible filename stored in the generic part
of the entry's header is used.
-j junk paths. The archive's directory structure is not recreated;
all files are deposited in the extraction directory (by default,
the current one).
-J [BeOS only] junk file attributes. The file's BeOS file
attributes are not restored, just the file's data.
-J [MacOS only] ignore MacOS extra fields. All 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 lowercase. 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, 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(1), or with the -N option
of the Amiga port of zip(1), 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 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 support spaces in filenames.
Conversion of spaces 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 filenames. 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 wildcard) 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 directory
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 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.]
-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 labelled as well.
By default, volume labels are ignored.
-/ extensions
[Acorn only] overrides the extension list supplied by Unzip$Ext
environment variable. 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 locations 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 liberal behaviour, to
allow exact extraction of (older) archives that used ``../''
components to create multiple directory trees at the level of
the current extraction folder. This option does not enable
writing explicitly to the root directory (``/''). To achieve
this, it is necessary to set the extraction target folder to
root (e.g. -d / ). However, when the -: option is specified, it
is still possible to implicitly write to the root directory by
specifying enough ``../'' path components 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
suspicious 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
handle 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-compatibility 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
filenames 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 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 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(1),
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
description of -f above for details. This variable may also be
necessary to get timestamps of extracted files to be set correctly.
The WIN32 (Win9x/ME/NT4/2K/XP/2K3) port of unzip gets the timezone
configuration from the registry, assuming it is correctly set in the
Control Panel. The TZ variable is ignored for this port.
DECRYPTION
Encrypted archives are fully supported by Info-ZIP 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 archives 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(1) and zipcloak(1) 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 encoding 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 consequently 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- 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 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 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 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*normal_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 archive 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 characters) 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 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, 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 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(1), zip(1), zipcloak(1), zipgrep(1), zipinfo(1), zipnote(1), zipsplit(1)
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 Salisbury (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)
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