UNZIP

NAME

SYNOPSIS

DESCRIPTION

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 Unix egrep(1) (regular) expressions 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).

(Be sure to quote any character which 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 match directory separators (`/'), this option may be used to exclude any files which 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 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

-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.

-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 which already exist on disk and which 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) 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. 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.

-u

update existing files and create new ones if needed. This option performs the same function as the -f option, extracting (with query) files which are newer than those with the same name on disk, and in addition it extracts those files which do not already exist on disk. See -f above for information on setting the timezone properly.

-v

be verbose or print 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 -l info the compression method, compressed size, compression ratio and 32-bit CRC. 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 which might affect the program's operation (see also DECRYPTION below); and any options stored in environment variables which 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.

-b

treat all files as binary (no text conversions). This is a shortcut for ---a.

-C

match filenames case-insensitively. 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 filesystems 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 files in both the normal file list and the excluded-file list (xlist).

-j

junk paths. The archive's directory structure is not recreated; all files are deposited in the extraction directory (by default, the current one).

-L

convert to lowercase any filename originating on an uppercase-only operating system or filesystem. (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 filesystems (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 filesystem 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.

-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 which 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.

-o

overwrite existing files without prompting. This is a dangerous option, so use it with care. (It is often used with -f, however.)

-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 which 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.

-U

(obsolete; to be removed in a future release) 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 filesystems which limit filenames to particularly short lengths, the version numbers may be truncated or stripped regardless of this option.)

-X

[VMS] restore owner/protection info (may require system privileges). Ordinary file attributes are always restored, but this option allows UICs to be restored as well. [The next version of unzip will support Unix UID/GID info as well, and possibly NT permissions.]

-$

[MS-DOS, OS/2, NT, Amiga] 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.

ENVIRONMENT OPTIONS

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

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:

(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(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 in order for timestamps on extracted files to be set correctly.  

DECRYPTION

Because of the separate distribution, not all compiled versions of unzip 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.

There are no runtime options for decryption; 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; it does this by testing a 12-byte header. 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 which 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) is taken as a signal to skip all further prompting. Only unencrypted files in the archive(s) will thereafter be extracted. (Actually 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.)

Note that there is presently no way to avoid interactive decryption. This is another security feature: plaintext passwords given on the command line or stored in files constitute a risk because they may be seen by others. Future releases may (under protest, with great disapproval) support such shenanigans.  

EXAMPLES

To extract all members of letters.zip into the current directory only:

To test letters.zip, printing only a summary message indicating whether the archive is OK or not:

To test all zipfiles in the current directory, printing only the summaries:

(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):

To extract the binary file paper1.dvi to standard output and pipe it to a printing program:

To extract all FORTRAN and C source files--*.f, *.c, *.h, and Makefile--into the /tmp directory:

(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):

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 which might be marked ``binary''):

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 to date contain no timezone information, and a ``newer'' file from an eastern timezone may, in fact, be older):

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):

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.:

In the last five examples, assume that UNZIP or UNZIP_OPTS is set to -q. To do a singly quiet listing:

To do a doubly quiet listing:

(Note that the ``.zip'' is generally not necessary.) To do a standard listing:

or

or  

TIPS

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

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.

4-8

unzip was unable to allocate memory for one or more buffers.

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.

VMS interprets standard Unix (or PC) return values as other, scarier-looking things, so by default unzip always returns 0 (which reportedly gets converted into a VMS status of 1--i.e., success). There are two compilation options available to modify or expand upon this behavior: defining RETURN_CODES results in a human-readable explanation of what the real error status was (but still with a faked ``success'' exit value), while defining RETURN_SEVERITY causes unzip to exit with a ``real'' VMS status. The latter behavior will become the default in future versions unless it is found to conflict with officially defined VMS 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 and 9-11, and 4 (fatal error) for the remaining ones (3-8, 50, 51). Check the ``unzip -v'' output to see whether RETURN_SEVERITY was defined at compilation time.  

BUGS

[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, unzip may hang the system, requiring a reboot. Instead, press control-C (or control-Break) to terminate unzip.

Under DEC Ultrix, unzip will sometimes fail on long zipfiles (bad CRC, not always reproducible). This is apparently due either to a hardware bug (cache memory) or an operating system bug (improper handling of page faults?).

Dates and times of stored directories are not restored.

[OS/2] Extended attributes for existing directories are never updated. This is a limitation of the operating system; unzip has no way to determine whether the stored attributes are newer or older than the existing ones.

[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

AUTHORS

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)

Index

NAME

SYNOPSIS

DESCRIPTION

ARGUMENTS

OPTIONS

MODIFIERS

ENVIRONMENT OPTIONS

DECRYPTION

EXAMPLES

TIPS

DIAGNOSTICS

BUGS

SEE ALSO

AUTHORS

VERSIONS