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.TP
.B \-:
[all but Acorn, VM/CMS, MVS, Tandem] allows to extract archive members into
locations outside of the current `` extraction root folder''. For security
reasons, \fIunzip\fP normally removes ``parent dir'' path components
(``../'') from the names of extracted file.  This safety feature (new for
version 5.50) prevents \fIunzip\fP from accidentally writing files to
``sensitive'' areas outside the active extraction folder tree head.  The
\fB\-:\fP option lets \fIunzip\fP 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. \fB\-d / \fP).  However, when the
\fB\-:\fP 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.
.TP
.B \-^
[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, \fIunzip\fP applies a filter by
default that removes potentially dangerous control characters from the
extracted file names. The \fB-^\fP option allows to override this filter
in the rare case that embedded filename control characters are to be
intentionally restored.
.TP
.B \-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.
.PD
.\" =========================================================================
.SH "ENVIRONMENT OPTIONS"
\fIunzip\fP'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 \fB\-a\fP, \fB\-L\fP, \fB\-C\fP, \fB\-q\fP,
\fB\-o\fP, or \fB\-n\fP modifiers:  make \fIunzip\fP 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 \fIunzip\fP act as quietly as possible, only
reporting errors, one would use one of the following commands:
.TP
  Unix Bourne shell:
UNZIP=\-qq; export UNZIP
.TP
  Unix C shell:
setenv UNZIP \-qq
.TP
  OS/2 or MS-DOS:
set UNZIP=\-qq
.TP
  VMS (quotes for \fIlowercase\fP):
define UNZIP_OPTS "\-qq"
.PP
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
.PP
.EX
unzip \-\-q[\fIother options\fP] zipfile
.EE
.PP
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:
.PP
.EX
unzip \-t\-\-q zipfile
unzip \-\-\-qt zipfile
.EE
.PP
(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 \fInice\fP(1).
.PP
As suggested by the examples above, the default variable names are UNZIP_OPTS
for VMS (where the symbol used to install \fIunzip\fP as a foreign command
would otherwise be confused with the environment variable), and UNZIP
for all other operating systems.  For compatibility with \fIzip\fP(1L),
UNZIPOPT is also accepted (don't ask).  If both UNZIP and UNZIPOPT
are defined, however, UNZIP takes precedence.  \fIunzip\fP's diagnostic
option (\fB\-v\fP with no zipfile name) can be used to check the values
of all four possible \fIunzip\fP and \fIzipinfo\fP environment variables.
.PP
The timezone variable (TZ) should be set according to the local timezone
in order for the \fB\-f\fP and \fB\-u\fP to operate correctly.  See the
description of \fB\-f\fP 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 \fIunzip\fP gets the timezone
configuration from the registry, assuming it is correctly set in the
Control Panel.  The TZ variable is ignored for this port.
.PD
.\" =========================================================================
.SH 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.
.PP
Some compiled versions of \fIunzip\fP may not support decryption.