Section: Misc. Reference Manual Pages (1L)
Updated: 20 April 2009 (v6.0)
unzipsfx - self-extracting stub for prepending to ZIP archives
<name of unzipsfx+archive combo>
... [-x xfile(s)
is a modified version of unzip
(1L) designed to be
prepended to existing ZIP archives in order to form self-extracting archives.
Instead of taking its first non-flag argument to be the zipfile(s) to be
seeks itself under the name by which it was invoked
and tests or extracts the contents of the appended archive. Because the
executable stub adds bulk to the archive (the whole purpose of which is to
be as small as possible), a number of the less-vital capabilities in regular
have been removed. Among these are the usage (or help) screen,
the listing and diagnostic functions (-l
), the ability
to decompress older compression formats (the ``reduce,'' ``shrink'' and
``implode'' methods). The ability to extract to a directory other than
the current one can be selected as a compile-time option, which is now enabled
by default since UnZipSFX version 5.5. Similarly, decryption is supported as
a compile-time option but should be avoided unless the attached archive
contains encrypted files. Starting with release 5.5, another compile-time
option adds a simple ``run command after extraction'' feature. This feature
is currently incompatible with the ``extract to different directory''
feature and remains disabled by default.
self-extracting archives made with unzipsfx are no more (or less)
portable across different operating systems than is
the unzip executable itself. In general a self-extracting
archive made on
a particular Unix system, for example, will only self-extract under the same
flavor of Unix. Regular unzip may still be used to extract the
embedded archive as with any normal zipfile, although it will generate
a harmless warning about extra bytes at the beginning of the zipfile.
Despite this, however, the self-extracting archive is technically
not a valid ZIP archive, and PKUNZIP may be unable to test or extract
it. This limitation is due to the simplistic manner in which the archive
is created; the internal directory structure is not updated to reflect the
extra bytes prepended to the original zipfile.
An optional list of archive members to be processed.
Regular expressions (wildcards) similar to those in Unix egrep(1)
may be used to match multiple members. These wildcards 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 that might otherwise be interpreted or
modified by the operating system, particularly under Unix and VMS.)
- [-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 that are in subdirectories. For
example, ``foosfx *.[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
If unzipsfx is compiled with SFX_EXDIR defined, the following option
is also enabled:
- [-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). 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.
supports the following unzip
(1L) options: -c
(extract to standard output/screen), -f
(freshen and update existing files upon extraction), -t
archive) and -z
(print archive comment). All normal listing options
) have been removed, but the testing
) may be used as a ``poor man's'' listing. Alternatively,
those creating self-extracting archives may wish to include a short listing
in the zipfile comment.
See unzip(1L) for a more complete description of these options.
currently supports all unzip
(1L) modifiers: -a
(convert text files), -n
(never overwrite), -o
without prompting), -q
(operate quietly), -C
(convert uppercase-OS names to lowercase),
(junk paths) and -V
(retain version numbers); plus the
following operating-system specific options: -X
owner/protection info), -s
(convert spaces in filenames to underscores
[DOS, OS/2, NT]) and -$
(restore volume label [DOS, OS/2, NT, Amiga]).
(Support for regular ASCII text-conversion may be removed in future versions,
since it is simple enough for the archive's creator to ensure that text
files have the appropriate format for the local OS. EBCDIC conversion will
of course continue to be supported since the zipfile format implies ASCII
storage of text files.)
See unzip(1L) for a more complete description of these modifiers.
uses the same environment variables as unzip
although this is likely to be an issue only for the person creating and
testing the self-extracting archive. See unzip
(1L) for details.
Decryption is supported exactly as in unzip
(1L); that is, interactively
with a non-echoing prompt for the password(s). See unzip
details. Once again, note that if the archive has no encrypted files there
is no reason to use a version of unzipsfx
with decryption support;
that only adds to the size of the archive.
was compiled with CHEAP_SFX_AUTORUN defined, a simple
``command autorun'' feature is supported. You may enter a command into the
Zip archive comment, using the following format:
$AUTORUN$>[command line string]
When unzipsfx recognizes the ``$AUTORUN$>'' token at the beginning
of the Zip archive comment, the remainder of the first line of the comment
(until the first newline character) is passed as a shell command to the
operating system using the C rtl ``system'' function. Before executing
the command, unzipsfx displays the command on the console and prompts
the user for confirmation. When the user has switched off prompting by
specifying the -q option, autorun commands are never executed.
In case the archive comment contains additional lines of text, the remainder
of the archive comment following the first line is displayed normally, unless
quiet operation was requested by supplying a -q option.
To create a self-extracting archive letters
from a regular zipfile
and change the new archive's permissions to be
world-executable under Unix:
cat unzipsfx letters.zip > letters
chmod 755 letters
zip -A letters
To create the same archive under MS-DOS, OS/2 or NT (note the use of the
/b [binary] option to the copy command):
copy /b unzipsfx.exe+letters.zip letters.exe
zip -A letters.exe
copy unzipsfx.exe,letters.zip letters.exe
letters == "$currentdisk:[currentdir]letters.exe"
zip -A letters.exe
(The VMS append command may also be used. The second command installs
the new program as a ``foreign command'' capable of taking arguments. The
third line assumes that Zip is already installed as a foreign command.)
MakeSFX letters letters.zip UnZipSFX
(MakeSFX is included with the UnZip source distribution and with Amiga
binary distributions. ``zip -A'' doesn't work on Amiga self-extracting
To test (or list) the newly created self-extracting archive:
To test letters quietly, printing only a summary message indicating
whether the archive is OK or not:
To extract the complete contents into the current directory, recreating all
files and subdirectories as necessary:
To extract all *.txt files (in Unix quote the `*'):
To extract everything except the *.txt files:
letters -x *.txt
To extract only the README file to standard output (the screen):
letters -c README
To print only the zipfile comment:
The principle and fundamental limitation of unzipsfx
is that it is
not portable across architectures or operating systems, and therefore
neither are the resulting archives. For some architectures there is
limited portability, however (e.g., between some flavors of Intel-based Unix).
Another problem with the current implementation is that any archive
with ``junk'' prepended to the beginning technically is no longer a zipfile
(unless zip(1) is used to adjust the zipfile offsets appropriately,
as noted above). unzip(1) takes note of the prepended bytes
and ignores them since some file-transfer protocols, notably MacBinary, are
also known to prepend junk. But PKWARE's archiver suite may not be able to
deal with the modified archive unless its offsets have been adjusted.
unzipsfx has no knowledge of the user's PATH, so in general an archive
must either be in the current directory when it is invoked, or else a full
or relative path must be given. If a user attempts to extract the archive
from a directory in the PATH other than the current one, unzipsfx will
print a warning to the effect, ``can't find myself.'' This is always true
under Unix and may be true in some cases under MS-DOS, depending on the
compiler used (Microsoft C fully qualifies the program name, but other
compilers may not). Under OS/2 and NT there are operating-system calls
available that provide the full path name, so the archive may be invoked
from anywhere in the user's path. The situation is not known for AmigaDOS,
Atari TOS, MacOS, etc.
As noted above, a number of the normal unzip(1L) functions have
been removed in order to make unzipsfx smaller: usage and diagnostic
info, listing functions and extraction to other directories. Also, only
stored and deflated files are supported. The latter limitation is mainly
relevant to those who create SFX archives, however.
VMS users must know how to set up self-extracting archives as foreign
commands in order to use any of unzipsfx's options. This is not
necessary for simple extraction, but the command to do so then becomes,
e.g., ``run letters'' (to continue the examples given above).
unzipsfx on the Amiga requires the use of a special program, MakeSFX,
in order to create working self-extracting archives; simple concatenation
does not work. (For technically oriented users, the attached archive is
defined as a ``debug hunk.'') There may be compatibility problems between
the ROM levels of older Amigas and newer ones.
All current bugs in unzip(1L) exist in unzipsfx as well.
's exit status (error level) is identical to that of
(1L); see the corresponding man page.
The Info-ZIP home page is currently at
Greg Roelofs was responsible for the basic modifications to UnZip necessary
to create UnZipSFX. See unzip
(1L) for the current list of Zip-Bugs
authors, or the file CONTRIBS in the UnZip source distribution for the
full list of Info-ZIP contributors.