UNZIP(1) General Commands Manual 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 cre-
ated 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 inter-
preted 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 de-
limit 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 process-
ing. 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 direc-
tory; 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 nor-
mal 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 direc-
tory.
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 simi-
lar 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 al-
ready 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 cor-
rectly 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 Un-
Zip 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 en-
hanced 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 op-
tion 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 al-
ready 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 zip-
file 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 addi-
tional 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 re-
ported 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 af-
fect 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 ver-
bose 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 ex-
tracted 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 iden-
tification 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 sup-
posed 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 stan-
dard 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 when-
ever another file with the original name plus tilde already ex-
ists. 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 pre-
vent loss of existing data under all circumstances. For exam-
ple, 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 en-
tries 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 be-
low). Because some file systems are fully case-sensitive (no-
tably those under the Unix operating system) and because both
ZIP archives and unzip itself are portable across platforms, un-
zip'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-in-
sensitive. 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 ex-
cluded-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 exist-
ing files on the extraction path. On a case-sensitive file sys-
tem, unzip will never try to overwrite a file ``FOO'' when ex-
tracting 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 privi-
leges or impose a security risk). By specifying -D, unzip is
told to suppress restoration of timestamps for directories ex-
plicitly created from Zip archive entries. This option only ap-
plies 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 consis-
tency with the behaviour of BACKUP: file timestamps are re-
stored, timestamps of extracted directories are left at the cur-
rent 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 re-
store operation.
-F [Acorn only] suppress removal of NFS filetype extension from
stored filenames.
-F [non-Acorn systems supporting long filenames with embedded com-
mas, and only if compiled with ACORN_FTYPE_NFS defined] trans-
late 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. In-
stead, the most compatible filename stored in the generic part
of the entry's header is used.
-I CHARSET
[UNIX only] Specify a character encoding for UNIX and other
archives.
-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 attrib-
utes 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 attrib-
utes. 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-sensi-
tive one such as under Unix. By default unzip lists and ex-
tracts such filenames exactly as they're stored (excepting trun-
cation, conversion of unsupported characters, etc.); this option
causes the names of all files from certain systems to be con-
verted to lowercase. The -LL option forces conversion of every
filename to lowercase, regardless of the originating file sys-
tem.
-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. un-
zip 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 likeli-
hood 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, how-
ever, and is the only way to overwrite directory EAs under
OS/2.)
-O CHARSET
[UNIX only] Specify a character encoding for DOS, Windows and
OS/2 archives.
-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 utili-
ties.)
-q perform operations quietly (-qq = even quieter). Ordinarily un-
zip 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 awkward-
ness 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 ap-
plied 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 es-
cape 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 sus-
pected 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] modi-
fies the pattern matching routine so that both `?' (single-char
wildcard) and `*' (multi-char wildcard) do not match the direc-
tory 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 avail-
able on systems where the Zip archive's internal directory sepa-
rator 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 al-
lowing `/' 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 cer-
tain 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 re-
store 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 ac-
cess 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 num-
bers (``;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 un-
zip switch back to its previous, more liberal behaviour, to al-
low exact extraction of (older) archives that used ``../'' com-
ponents 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. Gener-
ally, this allows to embed ASCII control characters (or even so-
phisticated control sequences) in file names, at least on 'na-
tive' 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 de-
fault 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 charac-
ters are to be intentionally restored.
-2 [VMS] force unconditionally conversion of file names to
ODS2-compatible names. The default is to exploit the destina-
tion file system, preserving case and extended file name charac-
ters 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 envi-
ronment 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 up-
percase 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 pos-
sible, only reporting errors, one would use one of the following com-
mands:
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 UN-
ZIP_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 time-
zone in order for the -f and -u to operate correctly. See the descrip-
tion 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 dis-
abled in your compiled binary. However, since spring 2000, US export
restrictions have been liberated, and our source archives do now in-
clude 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 en-
crypted 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. un-
zip 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 at-
tacks 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 gener-
ated for the extracted data or else unzip will fail during the extrac-
tion because the ``decrypted'' bytes do not constitute a valid com-
pressed 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 al-
low 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 pass-
word 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 subdirecto-
ries 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 sum-
maries:
unzip -tq \*.zip
(The backslash before the asterisk is only required if the shell ex-
pands wildcards, as in Unix; double quotes could have been used in-
stead, 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 Make-
file--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 ``bi-
nary''):
unzip -aaCL source.zip "*.[fch]" makefile -d /tmp
To extract only newer versions of the files already in the current di-
rectory, without querying (NOTE: be careful of unzipping in one time-
zone a zipfile created in another--ZIP archives other than those cre-
ated 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 ex-
ample):
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 de-
fine a pair of aliases: tt for ``unzip -tq'' and ii for ``unzip -Z''
(or ``zipinfo''). One may then simply type ``tt zipfile'' to test an
archive, something that is worth making a habit of doing. With luck
unzip will report ``No errors detected in compressed data of zip-
file.zip,'' after which one may breathe a sigh of relief.
The maintainer also finds it useful to set the UNZIP environment vari-
able 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 process-
ing completed successfully anyway. This includes zip-
files where one or more files was skipped due to unsup-
ported compression method or encryption with an unknown
password.
2 a generic error in the zipfile format was detected. Pro-
cessing may have completed successfully anyway; some bro-
ken zipfiles created by other archivers have simple work-
arounds.
3 a severe error in the zipfile format was detected. Pro-
cessing 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 de-
compression.
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 decryp-
tion.
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_un-
zip_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 ex-
pand 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 ex-
tracted).
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 wrap-
ping of long lines. However, the code may fail to detect the correct
wrapping locations. First, TAB characters (and similar control se-
quences) 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 ex-
cept under Unix. (On Windows NT and successors, timestamps are now re-
stored.)
[MS-DOS] When extracting or testing files from an archive on a defec-
tive 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 con-
trol-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 de-
vices and character devices are not restored even if they are somehow
represented in the zipfile, nor are hard-linked files relinked. Basi-
cally the only file types restored by unzip are regular files, directo-
ries 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 as-
sociated 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 nor-
mally (with or without freshening/updating existing files), then over-
write 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 ig-
nored (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 ``over-
write'' choice does create a new version; the old version is not over-
written 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 co-
ordination, VMS, MS-DOS, Win32, shared code, general Zip and UnZip in-
tegration 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 Pe-
tersen hosting the original mailing list at WSMR-SimTel20. The full
list of contributors to UnZip has grown quite large; please refer to
the CONTRIBS file in the UnZip source distribution for a relatively
complete version.
VERSIONS
v1.2 15 Mar 89 Samuel H. Smith
v2.0 9 Sep 89 Samuel H. Smith
v2.x fall 1989 many Usenet contributors
v3.0 1 May 90 Info-ZIP (DPK, consolidator)
v3.1 15 Aug 90 Info-ZIP (DPK, consolidator)
v4.0 1 Dec 90 Info-ZIP (GRR, maintainer)
v4.1 12 May 91 Info-ZIP
v4.2 20 Mar 92 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.0 21 Aug 92 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.01 15 Jan 93 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.1 7 Feb 94 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.11 2 Aug 94 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.12 28 Aug 94 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.2 30 Apr 96 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.3 22 Apr 97 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.31 31 May 97 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.32 3 Nov 97 Info-ZIP (Zip-Bugs subgroup, GRR)
v5.4 28 Nov 98 Info-ZIP (Zip-Bugs subgroup, SPC)
v5.41 16 Apr 00 Info-ZIP (Zip-Bugs subgroup, SPC)
v5.42 14 Jan 01 Info-ZIP (Zip-Bugs subgroup, SPC)
v5.5 17 Feb 02 Info-ZIP (Zip-Bugs subgroup, SPC)
v5.51 22 May 04 Info-ZIP (Zip-Bugs subgroup, SPC)
v5.52 28 Feb 05 Info-ZIP (Zip-Bugs subgroup, SPC)
v6.0 20 Apr 09 Info-ZIP (Zip-Bugs subgroup, SPC)
Info-ZIP 20 April 2009 (v6.0) UNZIP(1)
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