Manual: unzip
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 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 it‐
self 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, par‐
ticularly under Unix and VMS.) If no matches are found, the specification is assumed to be a literal file‐
name; 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 per‐
mission 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 specifica‐
tion, 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 zip‐
info(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 automati‐
cally 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 ac‐
cess control lists (ACLs). In addition, the zipfile comment and individual file comments (if any) are dis‐
played. 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 ex‐
tracted 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 redun‐
dancy 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 ex‐
tracts 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, com‐
pressed 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 com‐
pression 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 hard‐
ware on which it was compiled, the compiler and version used, and the compilation date; any special compila‐
tion 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 con‐
junction with other options (e.g., -t) to produce more verbose or debugging output; this is not yet fully im‐
plemented 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 char‐
acter 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 identifica‐
tion 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 op‐
tion. 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 circum‐
stances. 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, insuf‐
ficient 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 se‐
lection 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, specify‐
ing ``makefile'' on the command line will only match ``makefile'' in the archive, not ``Makefile'' or ``MAKE‐
FILE'' (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 cre‐
ated from Zip archive entries. This option only applies to ports that support setting timestamps for directo‐
ries (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 direc‐
tories). 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 time‐
stamps 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 de‐
fault -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 ap‐
pended 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.
-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 di‐
rectory (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-up‐
percase 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 (Re‐
turn) key or the space bar. unzip can be terminated by pressing the ``q'' key and, on some systems, the En‐
ter/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.)
-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 sys‐
tems 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 en‐
ter passwords. (And where security is truly important, use strong encryption such as Pretty Good Privacy in‐
stead 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 extract‐
ing 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 awk‐
ward, 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 charac‐
ters, 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 file‐
name 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 sup‐
ported 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 sys‐
tem filenames. (Currently, UnZip uses the same pattern matching rules for both wildcard zipfile specifica‐
tions 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). Dou‐
bling 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, file‐
name 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 -: op‐
tion 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 extrac‐
tion 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 con‐
tain 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 al‐
lows 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". Embed‐
ded 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 fil‐
ter by default that removes potentially dangerous control characters from the extracted file names. The -^ op‐
tion allows to override this filter in the rare case that embedded filename control characters are to be in‐
tentionally 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-insensi‐
tively, 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 opera‐
tor'' 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 in‐
stall 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 cor‐
rectly. See the description of -f above for details. This variable may also be necessary to get timestamps of ex‐
tracted 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-/en‐
cryption 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 ``[de‐
cryption]'' 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 zip‐
file 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 incor‐
rect CRC will be generated for the extracted data or else unzip will fail during the extraction because the ``de‐
crypted'' 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 there‐
after be extracted. (In fact, that's not quite true; older versions of zip(1) and zipcloak(1) allowed null pass‐
words, 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; Win‐
dows 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 han‐
dling in unzip. On systems that use UTF-8 as native character encoding, unzip simply tries decryption with the na‐
tive 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 zip‐
file.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, ex‐
cept under VMS:
0 normal; no errors or warnings detected.
1 one or more warning errors were encountered, but processing completed successfully anyway. This in‐
cludes 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 er‐
rors, and (0x7fff000? + 16*normal_unzip_exit_status) for all other errors, where the `?' is 2 (error) for unzip val‐
ues 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 sin‐
gle-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 appar‐
ently 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, un‐
zip 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 ex‐
isting 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 fea‐
tures); 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 com‐
pression); 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)
Info-ZIP 20 April 2009 (v6.0) UNZIP(1)