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)