UNZIP
Section: Misc. Reference Manual Pages (1L)
Updated: 20 April 2009 (v6.0)
Page Index
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(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 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(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 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(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 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(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 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 labeled 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(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 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(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 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.
- 12
-
invalid zip file with overlapped components (possible zip bomb).
- 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(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 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)