UNZIP(1L) Info-ZIP UNZIP(1L)
20 April 2009 (v6.0)
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
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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
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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
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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
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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).
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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).
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-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.
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-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.
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-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
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(``;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.
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-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
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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
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20 April 2009 (v6.0)
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
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(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.:
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UNZIP(1L) Info-ZIP UNZIP(1L)
20 April 2009 (v6.0)
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.
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UNZIP(1L) Info-ZIP UNZIP(1L)
20 April 2009 (v6.0)
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
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UNZIP(1L) Info-ZIP UNZIP(1L)
20 April 2009 (v6.0)
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 */'').
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UNZIP(1L) Info-ZIP UNZIP(1L)
20 April 2009 (v6.0)
[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
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UNZIP(1L) Info-ZIP UNZIP(1L)
20 April 2009 (v6.0)
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)
- 19 - Formatted: November 14, 2024
