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)